The Experts below are selected from a list of 987 Experts worldwide ranked by ideXlab platform

Kazutoyo Yamada - One of the best experts on this subject based on the ideXlab platform.

  • Effects of Tip Clearance on the Stall Inception Process in an Axial Compressor Rotor
    Volume 6C: Turbomachinery, 2013
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Satoshi Gunjishima, Masato Furukawa, Yasunori Hara
    Abstract:

    The paper presents experimental and numerical studies on the effects of tip clearance on the stall inception process in a low-speed axial compressor rotor with a large tip clearance. It has been revealed that in the small tip clearance case, shortly after the spike disturbance which results from the leading-edge separation near the rotor tip appears, the tornado-like vortex is generated by the separation, and soon the compressor falls into stall. In the large tip clearance case, the experiment showed that the performance characteristic differs from that in the small tip clearance case at near-stall conditions. This implies that the stall inception process differs with the tip clearance size. The flow phenomenon in the stall inception leading to such difference has been investigated in this study. Pressure and velocity fields which were ensemble-averaged and phase-locked by the periodic multi-sampling technique were measured on the Casing wall and downstream of the rotor, respectively. In addition, to capture the unsteady flow phenomena inside the rotor, "Instantaneous Casing Pressure Field Measurement "was carried out: instantaneous Casing Pressure fields in one rotor passage region were measured by 30 high response Pressure transducers mounted on the Casing wall. In order to investigate further details of near-stall flow field for the large tip clearance, DES (Detached Eddy Simulation) has been conducted using a computational mesh with 120 million points. The results are compared with those from previous studies for the small tip clearance. As expected, the measurement results show notable differences in the near-stall flow field between the two tip clearance cases. The results from the Casing Pressure measurement show that high Pressure fluctuation appears on the Pressure side near the rotor leading-edge in the large tip clearance case. In the result of the velocity field measurement downstream of the rotor, high turbulence intensity is found near the Casing in the large tip clearance case. The numerical results reveal that the vortex breakdown occurs in the tip leakage vortex and induces the oscillation of the tip leakage vortex with its unsteady nature. The flow phenomena confirmed in the experimental results are clearly explained by considering the breakdown of the tip leakage vortex. The vortex breakdown gives rise to not only large blockage but also the rotating disturbance through the interaction of the fluctuating tip leakage vortex with the Pressure surface of the adjacent blade, and governs the stall inception process. Copyright © 2013 by ASME.

  • An Explanation for Flow Features of Spike-Type Stall Inception in an Axial Compressor Rotor
    Journal of Turbomachinery-transactions of The Asme, 2012
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Kenichiro Ken-ichiro Iwakiri, Masato Furukawa, Satoshi Gunjishima
    Abstract:

    The unsteady behavior and three-dimensional flow structure of spike-type stall inception in an axial compressor rotor were investigated by experimental and numerical analyses. Previous studies revealed that the test compressor falls into a mild stall after emergence of a spike, in which multiple stall cells, each consisting of a tornado-like vortex, are rotating. However, the flow mechanism from the spike onset to the mild stall remains unexplained. The purpose of this study is to describe the flow mechanism of a spike stall inception in a compressor. In order to capture the transient phenomena of spike-type stall inception experimentally, an instantaneous Casing Pressure field measurement technique was developed, in which 30 Pressure transducers measure an instantaneous Casing Pressure distribution inside the passage for one blade pitch at a rate of 25 samplings per blade passing period. This technique was applied to obtain the unsteady and transient Pressure fields on the Casing wall during the inception process of the spike stall. In addition, the details of the three-dimensional flow structure at the spike stall inception were analyzed by a numerical approach using the detached-eddy simulation (DES). The instantaneous Casing Pressure field measurement results at the stall inception show that a low-Pressure region starts traveling near the leading edge in the circumferential direction just after the spiky wave was detected in the Casing wall Pressure trace measured near the rotor leading edge. The DES results reveal the vortical flow structure behind the low-Pressure region on the Casing wall at the stall inception, showing that the low-Pressure region is caused by a tornado-like separation vortex resulting from a leading-edge separation near the rotor tip. A leading-edge separation occurs near the tip at the onset of the spike stall and grows to form the tornado-like vortex connecting the blade suction surface and the Casing wall. The Casing-side leg of the tornado-like vortex generating the low-Pressure region circumferentially moves around the leading-edge line. When the vortex grows large enough to interact with the leading edge of the next blade, the leading-edge separation begins to propagate, and then the compressor falls into a stall with decreasing performance.

  • An explanation for flow features of spike-type stall inception in an axial compressor rotor
    Volume 8: Turbomachinery Parts A B and C, 2012
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Kenichiro Ken-ichiro Iwakiri, Masato Furukawa, Satoshi Gunjishima
    Abstract:

    The unsteady behavior and three-dimensional flow structure of spike-type stall inception in an axial compressor rotor have been investigated by experimental and numerical analyses. Previous studies have revealed that the test compressor falls into a mild stall after emergence of a spike, in which multiple stall cells, each consisting of a tornado-like vortex, are rotating. However, the flow mechanism from the spike onset to the mild stall remains unexplained. The purpose of this study is to describe the flow mechanism of a spike stall inception in a compressor. In order to capture the transient phenomena of spike-type stall inception experimentally, an instantaneous Casing Pressure field measurement technique was developed, in which 30 Pressure transducers measure an instantaneous Casing Pressure distribution inside the passage for one blade pitch at a rate of 25 samplings per blade passing period. This technique was applied to obtain the unsteady and transient Pressure fields on the Casing wall during the inception process of the spike stall. In addition, the details of the three-dimensional flow structure at the spike stall inception have been analyzed by a numerical approach using the detached-eddy simulation (DES). The instantaneous Casing Pressure field measurement results at the stall inception show that a low-Pressure region starts traveling near the leading edge in the circumferential direction just after the spiky wave was detected in the Casing wall Pressure trace measured near the rotor leading edge. The DES results reveal the vortical flow structure behind the low-Pressure region on the Casing wall at the stall inception, showing that the low-Pressure region is caused by a tornado-like separation vortex resulting from a leading-edge separation near the rotor tip. A leading-edge separation occurs near the tip at the onset of the spike stall and grows to form the tornado-like vortex connecting the blade suction surface and the Casing wall. The Casing-side leg of the tornado-like vortex generating the low-Pressure region circumferentially moves around the leading-edge line. When the vortex grows large enough to interact with the leading edge of the next blade, the leading-edge separation begins to propagate, and then, the compressor falls into a stall with decreasing performance.

  • An Explanation for Flow Features of Spike-Type Stall Inception in an Axial Compressor Rotor
    Journal of Turbomachinery, 2012
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Satoshi Gunjishima, Kenichiro Ken-ichiro Iwakiri, Hisataka Fukushima, Seiichi Ibaraki, Masato Furukawa, Isao Tomita
    Abstract:

    The paper presents experimental and numerical studies on the effects of tip clearance on the stall inception process in a low-speed axial compressor rotor with a large tip clearance. It has been revealed that in the small tip clearance case, shortly after the spike disturbance which results from the leading-edge separation near the rotor tip appears, the tornado-like vortex is generated by the separation, and soon the compressor falls into stall. In the large tip clearance case, the experiment showed that the performance characteristic differs from that in the small tip clearance case at near-stall conditions. This implies that the stall inception process differs with the tip clearance size. The flow phenomenon in the stall inception leading to such difference has been investigated in this study. Pressure and velocity fields which were ensemble-averaged and phase-locked by the periodic multi-sampling technique were measured on the Casing wall and downstream of the rotor, respectively. In addition, to capture the unsteady flow phenomena inside the rotor, "Instantaneous Casing Pressure Field Measurement "was carried out: instantaneous Casing Pressure fields in one rotor passage region were measured by 30 high response Pressure transducers mounted on the Casing wall. In order to investigate further details of near-stall flow field for the large tip clearance, DES (Detached Eddy Simulation) has been conducted using a computational mesh with 120 million points. The results are compared with those from previous studies for the small tip clearance. As expected, the measurement results show notable differences in the near-stall flow field between the two tip clearance cases. The results from the Casing Pressure measurement show that high Pressure fluctuation appears on the Pressure side near the rotor leading-edge in the large tip clearance case. In the result of the velocity field measurement downstream of the rotor, high turbulence intensity is found near the Casing in the large tip clearance case. The numerical results reveal that the vortex breakdown occurs in the tip leakage vortex and induces the oscillation of the tip leakage vortex with its unsteady nature. The flow phenomena confirmed in the experimental results are clearly explained by considering the breakdown of the tip leakage vortex. The vortex breakdown gives rise to not only large blockage but also the rotating disturbance through the interaction of the fluctuating tip leakage vortex with the Pressure surface of the adjacent blade, and governs the stall inception process. Copyright © 2013 by ASME.

Satoshi Gunjishima - One of the best experts on this subject based on the ideXlab platform.

  • Effects of Tip Clearance on the Stall Inception Process in an Axial Compressor Rotor
    Volume 6C: Turbomachinery, 2013
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Satoshi Gunjishima, Masato Furukawa, Yasunori Hara
    Abstract:

    The paper presents experimental and numerical studies on the effects of tip clearance on the stall inception process in a low-speed axial compressor rotor with a large tip clearance. It has been revealed that in the small tip clearance case, shortly after the spike disturbance which results from the leading-edge separation near the rotor tip appears, the tornado-like vortex is generated by the separation, and soon the compressor falls into stall. In the large tip clearance case, the experiment showed that the performance characteristic differs from that in the small tip clearance case at near-stall conditions. This implies that the stall inception process differs with the tip clearance size. The flow phenomenon in the stall inception leading to such difference has been investigated in this study. Pressure and velocity fields which were ensemble-averaged and phase-locked by the periodic multi-sampling technique were measured on the Casing wall and downstream of the rotor, respectively. In addition, to capture the unsteady flow phenomena inside the rotor, "Instantaneous Casing Pressure Field Measurement "was carried out: instantaneous Casing Pressure fields in one rotor passage region were measured by 30 high response Pressure transducers mounted on the Casing wall. In order to investigate further details of near-stall flow field for the large tip clearance, DES (Detached Eddy Simulation) has been conducted using a computational mesh with 120 million points. The results are compared with those from previous studies for the small tip clearance. As expected, the measurement results show notable differences in the near-stall flow field between the two tip clearance cases. The results from the Casing Pressure measurement show that high Pressure fluctuation appears on the Pressure side near the rotor leading-edge in the large tip clearance case. In the result of the velocity field measurement downstream of the rotor, high turbulence intensity is found near the Casing in the large tip clearance case. The numerical results reveal that the vortex breakdown occurs in the tip leakage vortex and induces the oscillation of the tip leakage vortex with its unsteady nature. The flow phenomena confirmed in the experimental results are clearly explained by considering the breakdown of the tip leakage vortex. The vortex breakdown gives rise to not only large blockage but also the rotating disturbance through the interaction of the fluctuating tip leakage vortex with the Pressure surface of the adjacent blade, and governs the stall inception process. Copyright © 2013 by ASME.

  • An Explanation for Flow Features of Spike-Type Stall Inception in an Axial Compressor Rotor
    Journal of Turbomachinery-transactions of The Asme, 2012
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Kenichiro Ken-ichiro Iwakiri, Masato Furukawa, Satoshi Gunjishima
    Abstract:

    The unsteady behavior and three-dimensional flow structure of spike-type stall inception in an axial compressor rotor were investigated by experimental and numerical analyses. Previous studies revealed that the test compressor falls into a mild stall after emergence of a spike, in which multiple stall cells, each consisting of a tornado-like vortex, are rotating. However, the flow mechanism from the spike onset to the mild stall remains unexplained. The purpose of this study is to describe the flow mechanism of a spike stall inception in a compressor. In order to capture the transient phenomena of spike-type stall inception experimentally, an instantaneous Casing Pressure field measurement technique was developed, in which 30 Pressure transducers measure an instantaneous Casing Pressure distribution inside the passage for one blade pitch at a rate of 25 samplings per blade passing period. This technique was applied to obtain the unsteady and transient Pressure fields on the Casing wall during the inception process of the spike stall. In addition, the details of the three-dimensional flow structure at the spike stall inception were analyzed by a numerical approach using the detached-eddy simulation (DES). The instantaneous Casing Pressure field measurement results at the stall inception show that a low-Pressure region starts traveling near the leading edge in the circumferential direction just after the spiky wave was detected in the Casing wall Pressure trace measured near the rotor leading edge. The DES results reveal the vortical flow structure behind the low-Pressure region on the Casing wall at the stall inception, showing that the low-Pressure region is caused by a tornado-like separation vortex resulting from a leading-edge separation near the rotor tip. A leading-edge separation occurs near the tip at the onset of the spike stall and grows to form the tornado-like vortex connecting the blade suction surface and the Casing wall. The Casing-side leg of the tornado-like vortex generating the low-Pressure region circumferentially moves around the leading-edge line. When the vortex grows large enough to interact with the leading edge of the next blade, the leading-edge separation begins to propagate, and then the compressor falls into a stall with decreasing performance.

  • An explanation for flow features of spike-type stall inception in an axial compressor rotor
    Volume 8: Turbomachinery Parts A B and C, 2012
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Kenichiro Ken-ichiro Iwakiri, Masato Furukawa, Satoshi Gunjishima
    Abstract:

    The unsteady behavior and three-dimensional flow structure of spike-type stall inception in an axial compressor rotor have been investigated by experimental and numerical analyses. Previous studies have revealed that the test compressor falls into a mild stall after emergence of a spike, in which multiple stall cells, each consisting of a tornado-like vortex, are rotating. However, the flow mechanism from the spike onset to the mild stall remains unexplained. The purpose of this study is to describe the flow mechanism of a spike stall inception in a compressor. In order to capture the transient phenomena of spike-type stall inception experimentally, an instantaneous Casing Pressure field measurement technique was developed, in which 30 Pressure transducers measure an instantaneous Casing Pressure distribution inside the passage for one blade pitch at a rate of 25 samplings per blade passing period. This technique was applied to obtain the unsteady and transient Pressure fields on the Casing wall during the inception process of the spike stall. In addition, the details of the three-dimensional flow structure at the spike stall inception have been analyzed by a numerical approach using the detached-eddy simulation (DES). The instantaneous Casing Pressure field measurement results at the stall inception show that a low-Pressure region starts traveling near the leading edge in the circumferential direction just after the spiky wave was detected in the Casing wall Pressure trace measured near the rotor leading edge. The DES results reveal the vortical flow structure behind the low-Pressure region on the Casing wall at the stall inception, showing that the low-Pressure region is caused by a tornado-like separation vortex resulting from a leading-edge separation near the rotor tip. A leading-edge separation occurs near the tip at the onset of the spike stall and grows to form the tornado-like vortex connecting the blade suction surface and the Casing wall. The Casing-side leg of the tornado-like vortex generating the low-Pressure region circumferentially moves around the leading-edge line. When the vortex grows large enough to interact with the leading edge of the next blade, the leading-edge separation begins to propagate, and then, the compressor falls into a stall with decreasing performance.

  • An Explanation for Flow Features of Spike-Type Stall Inception in an Axial Compressor Rotor
    Journal of Turbomachinery, 2012
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Satoshi Gunjishima, Kenichiro Ken-ichiro Iwakiri, Hisataka Fukushima, Seiichi Ibaraki, Masato Furukawa, Isao Tomita
    Abstract:

    The paper presents experimental and numerical studies on the effects of tip clearance on the stall inception process in a low-speed axial compressor rotor with a large tip clearance. It has been revealed that in the small tip clearance case, shortly after the spike disturbance which results from the leading-edge separation near the rotor tip appears, the tornado-like vortex is generated by the separation, and soon the compressor falls into stall. In the large tip clearance case, the experiment showed that the performance characteristic differs from that in the small tip clearance case at near-stall conditions. This implies that the stall inception process differs with the tip clearance size. The flow phenomenon in the stall inception leading to such difference has been investigated in this study. Pressure and velocity fields which were ensemble-averaged and phase-locked by the periodic multi-sampling technique were measured on the Casing wall and downstream of the rotor, respectively. In addition, to capture the unsteady flow phenomena inside the rotor, "Instantaneous Casing Pressure Field Measurement "was carried out: instantaneous Casing Pressure fields in one rotor passage region were measured by 30 high response Pressure transducers mounted on the Casing wall. In order to investigate further details of near-stall flow field for the large tip clearance, DES (Detached Eddy Simulation) has been conducted using a computational mesh with 120 million points. The results are compared with those from previous studies for the small tip clearance. As expected, the measurement results show notable differences in the near-stall flow field between the two tip clearance cases. The results from the Casing Pressure measurement show that high Pressure fluctuation appears on the Pressure side near the rotor leading-edge in the large tip clearance case. In the result of the velocity field measurement downstream of the rotor, high turbulence intensity is found near the Casing in the large tip clearance case. The numerical results reveal that the vortex breakdown occurs in the tip leakage vortex and induces the oscillation of the tip leakage vortex with its unsteady nature. The flow phenomena confirmed in the experimental results are clearly explained by considering the breakdown of the tip leakage vortex. The vortex breakdown gives rise to not only large blockage but also the rotating disturbance through the interaction of the fluctuating tip leakage vortex with the Pressure surface of the adjacent blade, and governs the stall inception process. Copyright © 2013 by ASME.

Hiroaki Kikuta - One of the best experts on this subject based on the ideXlab platform.

  • Effects of Tip Clearance on the Stall Inception Process in an Axial Compressor Rotor
    Volume 6C: Turbomachinery, 2013
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Satoshi Gunjishima, Masato Furukawa, Yasunori Hara
    Abstract:

    The paper presents experimental and numerical studies on the effects of tip clearance on the stall inception process in a low-speed axial compressor rotor with a large tip clearance. It has been revealed that in the small tip clearance case, shortly after the spike disturbance which results from the leading-edge separation near the rotor tip appears, the tornado-like vortex is generated by the separation, and soon the compressor falls into stall. In the large tip clearance case, the experiment showed that the performance characteristic differs from that in the small tip clearance case at near-stall conditions. This implies that the stall inception process differs with the tip clearance size. The flow phenomenon in the stall inception leading to such difference has been investigated in this study. Pressure and velocity fields which were ensemble-averaged and phase-locked by the periodic multi-sampling technique were measured on the Casing wall and downstream of the rotor, respectively. In addition, to capture the unsteady flow phenomena inside the rotor, "Instantaneous Casing Pressure Field Measurement "was carried out: instantaneous Casing Pressure fields in one rotor passage region were measured by 30 high response Pressure transducers mounted on the Casing wall. In order to investigate further details of near-stall flow field for the large tip clearance, DES (Detached Eddy Simulation) has been conducted using a computational mesh with 120 million points. The results are compared with those from previous studies for the small tip clearance. As expected, the measurement results show notable differences in the near-stall flow field between the two tip clearance cases. The results from the Casing Pressure measurement show that high Pressure fluctuation appears on the Pressure side near the rotor leading-edge in the large tip clearance case. In the result of the velocity field measurement downstream of the rotor, high turbulence intensity is found near the Casing in the large tip clearance case. The numerical results reveal that the vortex breakdown occurs in the tip leakage vortex and induces the oscillation of the tip leakage vortex with its unsteady nature. The flow phenomena confirmed in the experimental results are clearly explained by considering the breakdown of the tip leakage vortex. The vortex breakdown gives rise to not only large blockage but also the rotating disturbance through the interaction of the fluctuating tip leakage vortex with the Pressure surface of the adjacent blade, and governs the stall inception process. Copyright © 2013 by ASME.

  • An Explanation for Flow Features of Spike-Type Stall Inception in an Axial Compressor Rotor
    Journal of Turbomachinery-transactions of The Asme, 2012
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Kenichiro Ken-ichiro Iwakiri, Masato Furukawa, Satoshi Gunjishima
    Abstract:

    The unsteady behavior and three-dimensional flow structure of spike-type stall inception in an axial compressor rotor were investigated by experimental and numerical analyses. Previous studies revealed that the test compressor falls into a mild stall after emergence of a spike, in which multiple stall cells, each consisting of a tornado-like vortex, are rotating. However, the flow mechanism from the spike onset to the mild stall remains unexplained. The purpose of this study is to describe the flow mechanism of a spike stall inception in a compressor. In order to capture the transient phenomena of spike-type stall inception experimentally, an instantaneous Casing Pressure field measurement technique was developed, in which 30 Pressure transducers measure an instantaneous Casing Pressure distribution inside the passage for one blade pitch at a rate of 25 samplings per blade passing period. This technique was applied to obtain the unsteady and transient Pressure fields on the Casing wall during the inception process of the spike stall. In addition, the details of the three-dimensional flow structure at the spike stall inception were analyzed by a numerical approach using the detached-eddy simulation (DES). The instantaneous Casing Pressure field measurement results at the stall inception show that a low-Pressure region starts traveling near the leading edge in the circumferential direction just after the spiky wave was detected in the Casing wall Pressure trace measured near the rotor leading edge. The DES results reveal the vortical flow structure behind the low-Pressure region on the Casing wall at the stall inception, showing that the low-Pressure region is caused by a tornado-like separation vortex resulting from a leading-edge separation near the rotor tip. A leading-edge separation occurs near the tip at the onset of the spike stall and grows to form the tornado-like vortex connecting the blade suction surface and the Casing wall. The Casing-side leg of the tornado-like vortex generating the low-Pressure region circumferentially moves around the leading-edge line. When the vortex grows large enough to interact with the leading edge of the next blade, the leading-edge separation begins to propagate, and then the compressor falls into a stall with decreasing performance.

  • An explanation for flow features of spike-type stall inception in an axial compressor rotor
    Volume 8: Turbomachinery Parts A B and C, 2012
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Kenichiro Ken-ichiro Iwakiri, Masato Furukawa, Satoshi Gunjishima
    Abstract:

    The unsteady behavior and three-dimensional flow structure of spike-type stall inception in an axial compressor rotor have been investigated by experimental and numerical analyses. Previous studies have revealed that the test compressor falls into a mild stall after emergence of a spike, in which multiple stall cells, each consisting of a tornado-like vortex, are rotating. However, the flow mechanism from the spike onset to the mild stall remains unexplained. The purpose of this study is to describe the flow mechanism of a spike stall inception in a compressor. In order to capture the transient phenomena of spike-type stall inception experimentally, an instantaneous Casing Pressure field measurement technique was developed, in which 30 Pressure transducers measure an instantaneous Casing Pressure distribution inside the passage for one blade pitch at a rate of 25 samplings per blade passing period. This technique was applied to obtain the unsteady and transient Pressure fields on the Casing wall during the inception process of the spike stall. In addition, the details of the three-dimensional flow structure at the spike stall inception have been analyzed by a numerical approach using the detached-eddy simulation (DES). The instantaneous Casing Pressure field measurement results at the stall inception show that a low-Pressure region starts traveling near the leading edge in the circumferential direction just after the spiky wave was detected in the Casing wall Pressure trace measured near the rotor leading edge. The DES results reveal the vortical flow structure behind the low-Pressure region on the Casing wall at the stall inception, showing that the low-Pressure region is caused by a tornado-like separation vortex resulting from a leading-edge separation near the rotor tip. A leading-edge separation occurs near the tip at the onset of the spike stall and grows to form the tornado-like vortex connecting the blade suction surface and the Casing wall. The Casing-side leg of the tornado-like vortex generating the low-Pressure region circumferentially moves around the leading-edge line. When the vortex grows large enough to interact with the leading edge of the next blade, the leading-edge separation begins to propagate, and then, the compressor falls into a stall with decreasing performance.

  • An Explanation for Flow Features of Spike-Type Stall Inception in an Axial Compressor Rotor
    Journal of Turbomachinery, 2012
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Satoshi Gunjishima, Kenichiro Ken-ichiro Iwakiri, Hisataka Fukushima, Seiichi Ibaraki, Masato Furukawa, Isao Tomita
    Abstract:

    The paper presents experimental and numerical studies on the effects of tip clearance on the stall inception process in a low-speed axial compressor rotor with a large tip clearance. It has been revealed that in the small tip clearance case, shortly after the spike disturbance which results from the leading-edge separation near the rotor tip appears, the tornado-like vortex is generated by the separation, and soon the compressor falls into stall. In the large tip clearance case, the experiment showed that the performance characteristic differs from that in the small tip clearance case at near-stall conditions. This implies that the stall inception process differs with the tip clearance size. The flow phenomenon in the stall inception leading to such difference has been investigated in this study. Pressure and velocity fields which were ensemble-averaged and phase-locked by the periodic multi-sampling technique were measured on the Casing wall and downstream of the rotor, respectively. In addition, to capture the unsteady flow phenomena inside the rotor, "Instantaneous Casing Pressure Field Measurement "was carried out: instantaneous Casing Pressure fields in one rotor passage region were measured by 30 high response Pressure transducers mounted on the Casing wall. In order to investigate further details of near-stall flow field for the large tip clearance, DES (Detached Eddy Simulation) has been conducted using a computational mesh with 120 million points. The results are compared with those from previous studies for the small tip clearance. As expected, the measurement results show notable differences in the near-stall flow field between the two tip clearance cases. The results from the Casing Pressure measurement show that high Pressure fluctuation appears on the Pressure side near the rotor leading-edge in the large tip clearance case. In the result of the velocity field measurement downstream of the rotor, high turbulence intensity is found near the Casing in the large tip clearance case. The numerical results reveal that the vortex breakdown occurs in the tip leakage vortex and induces the oscillation of the tip leakage vortex with its unsteady nature. The flow phenomena confirmed in the experimental results are clearly explained by considering the breakdown of the tip leakage vortex. The vortex breakdown gives rise to not only large blockage but also the rotating disturbance through the interaction of the fluctuating tip leakage vortex with the Pressure surface of the adjacent blade, and governs the stall inception process. Copyright © 2013 by ASME.

Masato Furukawa - One of the best experts on this subject based on the ideXlab platform.

  • Effects of Tip Clearance on the Stall Inception Process in an Axial Compressor Rotor
    Volume 6C: Turbomachinery, 2013
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Satoshi Gunjishima, Masato Furukawa, Yasunori Hara
    Abstract:

    The paper presents experimental and numerical studies on the effects of tip clearance on the stall inception process in a low-speed axial compressor rotor with a large tip clearance. It has been revealed that in the small tip clearance case, shortly after the spike disturbance which results from the leading-edge separation near the rotor tip appears, the tornado-like vortex is generated by the separation, and soon the compressor falls into stall. In the large tip clearance case, the experiment showed that the performance characteristic differs from that in the small tip clearance case at near-stall conditions. This implies that the stall inception process differs with the tip clearance size. The flow phenomenon in the stall inception leading to such difference has been investigated in this study. Pressure and velocity fields which were ensemble-averaged and phase-locked by the periodic multi-sampling technique were measured on the Casing wall and downstream of the rotor, respectively. In addition, to capture the unsteady flow phenomena inside the rotor, "Instantaneous Casing Pressure Field Measurement "was carried out: instantaneous Casing Pressure fields in one rotor passage region were measured by 30 high response Pressure transducers mounted on the Casing wall. In order to investigate further details of near-stall flow field for the large tip clearance, DES (Detached Eddy Simulation) has been conducted using a computational mesh with 120 million points. The results are compared with those from previous studies for the small tip clearance. As expected, the measurement results show notable differences in the near-stall flow field between the two tip clearance cases. The results from the Casing Pressure measurement show that high Pressure fluctuation appears on the Pressure side near the rotor leading-edge in the large tip clearance case. In the result of the velocity field measurement downstream of the rotor, high turbulence intensity is found near the Casing in the large tip clearance case. The numerical results reveal that the vortex breakdown occurs in the tip leakage vortex and induces the oscillation of the tip leakage vortex with its unsteady nature. The flow phenomena confirmed in the experimental results are clearly explained by considering the breakdown of the tip leakage vortex. The vortex breakdown gives rise to not only large blockage but also the rotating disturbance through the interaction of the fluctuating tip leakage vortex with the Pressure surface of the adjacent blade, and governs the stall inception process. Copyright © 2013 by ASME.

  • An Explanation for Flow Features of Spike-Type Stall Inception in an Axial Compressor Rotor
    Journal of Turbomachinery-transactions of The Asme, 2012
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Kenichiro Ken-ichiro Iwakiri, Masato Furukawa, Satoshi Gunjishima
    Abstract:

    The unsteady behavior and three-dimensional flow structure of spike-type stall inception in an axial compressor rotor were investigated by experimental and numerical analyses. Previous studies revealed that the test compressor falls into a mild stall after emergence of a spike, in which multiple stall cells, each consisting of a tornado-like vortex, are rotating. However, the flow mechanism from the spike onset to the mild stall remains unexplained. The purpose of this study is to describe the flow mechanism of a spike stall inception in a compressor. In order to capture the transient phenomena of spike-type stall inception experimentally, an instantaneous Casing Pressure field measurement technique was developed, in which 30 Pressure transducers measure an instantaneous Casing Pressure distribution inside the passage for one blade pitch at a rate of 25 samplings per blade passing period. This technique was applied to obtain the unsteady and transient Pressure fields on the Casing wall during the inception process of the spike stall. In addition, the details of the three-dimensional flow structure at the spike stall inception were analyzed by a numerical approach using the detached-eddy simulation (DES). The instantaneous Casing Pressure field measurement results at the stall inception show that a low-Pressure region starts traveling near the leading edge in the circumferential direction just after the spiky wave was detected in the Casing wall Pressure trace measured near the rotor leading edge. The DES results reveal the vortical flow structure behind the low-Pressure region on the Casing wall at the stall inception, showing that the low-Pressure region is caused by a tornado-like separation vortex resulting from a leading-edge separation near the rotor tip. A leading-edge separation occurs near the tip at the onset of the spike stall and grows to form the tornado-like vortex connecting the blade suction surface and the Casing wall. The Casing-side leg of the tornado-like vortex generating the low-Pressure region circumferentially moves around the leading-edge line. When the vortex grows large enough to interact with the leading edge of the next blade, the leading-edge separation begins to propagate, and then the compressor falls into a stall with decreasing performance.

  • An explanation for flow features of spike-type stall inception in an axial compressor rotor
    Volume 8: Turbomachinery Parts A B and C, 2012
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Kenichiro Ken-ichiro Iwakiri, Masato Furukawa, Satoshi Gunjishima
    Abstract:

    The unsteady behavior and three-dimensional flow structure of spike-type stall inception in an axial compressor rotor have been investigated by experimental and numerical analyses. Previous studies have revealed that the test compressor falls into a mild stall after emergence of a spike, in which multiple stall cells, each consisting of a tornado-like vortex, are rotating. However, the flow mechanism from the spike onset to the mild stall remains unexplained. The purpose of this study is to describe the flow mechanism of a spike stall inception in a compressor. In order to capture the transient phenomena of spike-type stall inception experimentally, an instantaneous Casing Pressure field measurement technique was developed, in which 30 Pressure transducers measure an instantaneous Casing Pressure distribution inside the passage for one blade pitch at a rate of 25 samplings per blade passing period. This technique was applied to obtain the unsteady and transient Pressure fields on the Casing wall during the inception process of the spike stall. In addition, the details of the three-dimensional flow structure at the spike stall inception have been analyzed by a numerical approach using the detached-eddy simulation (DES). The instantaneous Casing Pressure field measurement results at the stall inception show that a low-Pressure region starts traveling near the leading edge in the circumferential direction just after the spiky wave was detected in the Casing wall Pressure trace measured near the rotor leading edge. The DES results reveal the vortical flow structure behind the low-Pressure region on the Casing wall at the stall inception, showing that the low-Pressure region is caused by a tornado-like separation vortex resulting from a leading-edge separation near the rotor tip. A leading-edge separation occurs near the tip at the onset of the spike stall and grows to form the tornado-like vortex connecting the blade suction surface and the Casing wall. The Casing-side leg of the tornado-like vortex generating the low-Pressure region circumferentially moves around the leading-edge line. When the vortex grows large enough to interact with the leading edge of the next blade, the leading-edge separation begins to propagate, and then, the compressor falls into a stall with decreasing performance.

  • An Explanation for Flow Features of Spike-Type Stall Inception in an Axial Compressor Rotor
    Journal of Turbomachinery, 2012
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Satoshi Gunjishima, Kenichiro Ken-ichiro Iwakiri, Hisataka Fukushima, Seiichi Ibaraki, Masato Furukawa, Isao Tomita
    Abstract:

    The paper presents experimental and numerical studies on the effects of tip clearance on the stall inception process in a low-speed axial compressor rotor with a large tip clearance. It has been revealed that in the small tip clearance case, shortly after the spike disturbance which results from the leading-edge separation near the rotor tip appears, the tornado-like vortex is generated by the separation, and soon the compressor falls into stall. In the large tip clearance case, the experiment showed that the performance characteristic differs from that in the small tip clearance case at near-stall conditions. This implies that the stall inception process differs with the tip clearance size. The flow phenomenon in the stall inception leading to such difference has been investigated in this study. Pressure and velocity fields which were ensemble-averaged and phase-locked by the periodic multi-sampling technique were measured on the Casing wall and downstream of the rotor, respectively. In addition, to capture the unsteady flow phenomena inside the rotor, "Instantaneous Casing Pressure Field Measurement "was carried out: instantaneous Casing Pressure fields in one rotor passage region were measured by 30 high response Pressure transducers mounted on the Casing wall. In order to investigate further details of near-stall flow field for the large tip clearance, DES (Detached Eddy Simulation) has been conducted using a computational mesh with 120 million points. The results are compared with those from previous studies for the small tip clearance. As expected, the measurement results show notable differences in the near-stall flow field between the two tip clearance cases. The results from the Casing Pressure measurement show that high Pressure fluctuation appears on the Pressure side near the rotor leading-edge in the large tip clearance case. In the result of the velocity field measurement downstream of the rotor, high turbulence intensity is found near the Casing in the large tip clearance case. The numerical results reveal that the vortex breakdown occurs in the tip leakage vortex and induces the oscillation of the tip leakage vortex with its unsteady nature. The flow phenomena confirmed in the experimental results are clearly explained by considering the breakdown of the tip leakage vortex. The vortex breakdown gives rise to not only large blockage but also the rotating disturbance through the interaction of the fluctuating tip leakage vortex with the Pressure surface of the adjacent blade, and governs the stall inception process. Copyright © 2013 by ASME.

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  • An Explanation for Flow Features of Spike-Type Stall Inception in an Axial Compressor Rotor
    Journal of Turbomachinery, 2012
    Co-Authors: Kazutoyo Yamada, Hiroaki Kikuta, Satoshi Gunjishima, Kenichiro Ken-ichiro Iwakiri, Hisataka Fukushima, Seiichi Ibaraki, Masato Furukawa, Isao Tomita
    Abstract:

    The paper presents experimental and numerical studies on the effects of tip clearance on the stall inception process in a low-speed axial compressor rotor with a large tip clearance. It has been revealed that in the small tip clearance case, shortly after the spike disturbance which results from the leading-edge separation near the rotor tip appears, the tornado-like vortex is generated by the separation, and soon the compressor falls into stall. In the large tip clearance case, the experiment showed that the performance characteristic differs from that in the small tip clearance case at near-stall conditions. This implies that the stall inception process differs with the tip clearance size. The flow phenomenon in the stall inception leading to such difference has been investigated in this study. Pressure and velocity fields which were ensemble-averaged and phase-locked by the periodic multi-sampling technique were measured on the Casing wall and downstream of the rotor, respectively. In addition, to capture the unsteady flow phenomena inside the rotor, "Instantaneous Casing Pressure Field Measurement "was carried out: instantaneous Casing Pressure fields in one rotor passage region were measured by 30 high response Pressure transducers mounted on the Casing wall. In order to investigate further details of near-stall flow field for the large tip clearance, DES (Detached Eddy Simulation) has been conducted using a computational mesh with 120 million points. The results are compared with those from previous studies for the small tip clearance. As expected, the measurement results show notable differences in the near-stall flow field between the two tip clearance cases. The results from the Casing Pressure measurement show that high Pressure fluctuation appears on the Pressure side near the rotor leading-edge in the large tip clearance case. In the result of the velocity field measurement downstream of the rotor, high turbulence intensity is found near the Casing in the large tip clearance case. The numerical results reveal that the vortex breakdown occurs in the tip leakage vortex and induces the oscillation of the tip leakage vortex with its unsteady nature. The flow phenomena confirmed in the experimental results are clearly explained by considering the breakdown of the tip leakage vortex. The vortex breakdown gives rise to not only large blockage but also the rotating disturbance through the interaction of the fluctuating tip leakage vortex with the Pressure surface of the adjacent blade, and governs the stall inception process. Copyright © 2013 by ASME.