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Masato Furukawa - One of the best experts on this subject based on the ideXlab platform.
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large scale numerical simulation of unsteady flow field in a half ducted Propeller Fan using lattice boltzmann method
ASME JSME KSME 2015 Joint Fluids Engineering Conference AJKFluids 2015, 2015Co-Authors: Kazutoyo Yamada, Kazuya Kusano, Masato FurukawaAbstract:Recently, the lattice Boltzmann method (LBM) is being applied in turbomachinery field, regarded as a good candidate for tool of flow simulation as well as aerodynamic sound analysis.For better prediction of broadband noise with high frequecy, which is generally generated in high Reynolds number flows, not only high grid resolution is required to capture very small eddies of the sound source inside the turbulent boundary layer, but also the computation of acoustic field is often needed. In such case, the direct simulation of flow field and acoustic field is straight-forward and effective. However, the computational cost becomes extremely expensive. Moreover, for low Mach number flows the compressible Navier-Stokes simulation not only requires high-order scheme which is unsuitable for parallel computation, but also suffers from stiff problem. LBM is suitable for such simulation thanks to its advantages.In the present study, a large-scale numerical simulation of flow field around a half-ducted Propeller Fan is conducted with LBM, and its result is validated by comparing with the experimental result.Copyright © 2015 by JSME
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detached eddy simulation of unsteady flow field and prediction of aerodynamic sound in a half ducted Propeller Fan
ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1 Symposia – Parts A B C and D, 2011Co-Authors: Kazuya Kusano, Kazutoyo Yamada, Jaeho Jeong, Masato FurukawaAbstract:Three-dimensional structures and unsteady nature of vortical flow fields in a half ducted Propeller Fan have been investigated by a detached eddy simulation (DES) based on k-ω two-equation turbulence model. The validity of the numerical simulation performed in the present study was demonstrated by the comparison to LDV measurement results. The simulation shows the tip vortex is so strong that it dominates the flow field near the rotor tip. The tip vortex does not impinge on the pressure surface of the adjacent blade directly, however it interacts with the shroud surface and induces a separation vortex on the shroud. Furthermore, this separation vortex interacts with the pressure surface of the adjacent blade. These flow structures cause high pressure fluctuation on the shroud surface and the blade pressure surface. Besides, sound pressure levels were predicted by Ffowcs William-Hawkings equation based on Lighthill’s acoustic analogy using the unsteady surface pressure data obtained by DES. As a result, the degree of contribution by each flow structure to overall sound has been estimated quantitatively.Copyright © 2011 by JSME
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design of a Propeller Fan using 3 d inverse design method and cfd for high efficiency and low aerodynamic noise
2009 ASME Fluids Engineering Division Summer Conference FEDSM2009, 2009Co-Authors: Hidenobu Okamoto, Akira Goto, Masato FurukawaAbstract:Three-Dimensional Inverse Design Method, where the 3-D blade profile is designed for a specified blade loading distribution, has been applied for designing a Propeller Fan rotor with high efficiency and low noise. A variety of the blade loading distributions (pressure jump across the blade), vortex pattern (forced vortex, free vortex, and compound vortex) and the stacking conditions (sweep angles) were specified and the corresponding 3-D blade configurations were obtained. Among the 22 different designs, 14 Propeller Fan rotors including the reproduced baseline Fan were manufactured by a rapid prototyping based on a selective laser sintering system (SLS) and tested. It was confirmed experimentally that the best design achieved about 5.7 points improvement in the peak total-to-static efficiency and the 2.6dB(A) reduction in aerodynamic noise. The flow mechanisms leading to the higher efficiency and lower aerodynamic noise were discussed based on experiments and the RANS steady flow simulations. Based on these investigations, design guidelines for the inverse design of Propeller Fan rotors with higher efficiency and lower aerodynamic noise were proposed.Copyright © 2009 by ASME
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three dimensional structure of separated and vortical flow in a half ducted Propeller Fan
2007 5th Joint ASME JSME Fluids Engineering Summer Conference FEDSM 2007, 2007Co-Authors: J H Jeong, Kazuya Takahashi, Kenichiro Iwakiri, Masato FurukawaAbstract:Three-dimensional structure of separated and vortical flow field has been investigated by numerical analysis on a half-ducted Propeller Fan. Complicated flow phenomena in the Fan were captured by the Reynolds-averaged Navier-Stokes flow simulation (RANS) and a vortex structure identification technique based on the critical point theory. The flow field around the Fan rotor is dominated by the tip leakage vortex. The tip leakage vortex starts to be formed near the blade mid-chord and grows nearly in the tangential direction without vortex breakdown. In the rotor passage, the high vorticity flow around the tip leakage vortex core is impinging on the pressure surface of the adjacent blade. It is expected that the behavior of the tip leakage vortex plays a major role in characteristics of the Fan noise.Copyright © 2007 by ASME
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frequency characteristics of fluctuating pressure on rotor blade in a Propeller Fan
Jsme International Journal Series B-fluids and Thermal Engineering, 2003Co-Authors: Choonman Jang, Masato Furukawa, Masahiro InoueAbstract:A wavelet transform is introduced to analyze frequency characteristics of the fluctuating pressure on rotor blade in a Propeller Fan. The fluctuating pressure on the rotor blade is obtained by using the results of a large eddy simulation. The frequencies having high spectral peaks of the fluctuating pressure are determined by taking the time average of the local absolute modulus of the wavelet. The dominant frequency of the real-time pressure selected at the high pressure fluctuation region corresponds well to that of the fluctuating rotor torque and the experimental result of Fan noise. It is mainly generated due to the unsteady behavior of the vortical flow, such as the tip vortex and the leading edge separation vortex, in the Propeller Fan. A frequency in the separation bubble region on the suction surface is higher than that of the dominant frequency caused by the vortical flow.
佐々木 壮一 - One of the best experts on this subject based on the ideXlab platform.
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A Consideration on Broadband Noise by Wake Analysis of a Propeller Fan
Graduate School of Engineering Nagasaki University, 2017Co-Authors: 佐々木 壮一, 日高 央也Abstract:We predicted the broadband noise operating at the maximum efficiency point, that is, the design point of a Propeller Fan by the wake analysis. The relative flow in the design point separated at the pressure surface. In this case, it was deduced that the flow around the impeller may not interact with the neighbor blade. The blade load was distributed on the blade span widely under the condition of the design point; the velocity fluctuations of the same operation point became large than that of the off-design point. The results of the predicted noise indicated that the influence of the relative velocity on the broadband noise was larger than that of its velocity fluctuation
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Study of Relative Flow Field in the Blade Tip and Periodical Aerodynamic Noise of a Propeller Fan
Graduate School of Engineering Nagasaki University, 2015Co-Authors: 佐々木 壮一, 日高 央也Abstract:In order to clarify the main factor of the periodical aerodynamic noise in the off-design point of the Propeller Fan, the relative flow field in the blade tip is measured by the hot-wire anemometer with the phase-lock method. In particular, we discuss the influence of the rotational speed of the impeller experimentally for clarifying the relationship between the relative flow field and the periodical aerodynamic noise. When the Propeller Fan is operated at the off-design point, the periodaical aerodynamic noise is generated in the lower frequency domain than that of the blade passing frequency. The energy of the velocity fluctuation in the leading edge of the blade tip became large at the same frequency band of the periodical aerodynamic noise. We indicated experimentally that the leakage flow at the leading edge in the relative flow did not interfere to the next blade. These experimental results indicate the periodical aerodynamic noise was generated because the pressure fluctuation due to the leakage flow became strong
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Study of Periodical Aerodynamic Noise Generated due to Tip Vortex of a Propeller Fan (Influence on Number of Blades)
Graduate School of Engineering Nagasaki University, 2014Co-Authors: 佐々木 壮一, 村上 寛明Abstract:In order to discuss the major factor on the noise characteristics of a Propeller Fan, the influence of the number of blades on the periodical Fan noise generated due to the tip vortex is analyzed. The influence of the tip vortex on the Fan noise is argued by the measured internal flow. For the analysis of the structure on the mean flow in the blade passage, the phase of the unsteady signal of the wake is locked by the trigger signal synchronized with the rotation signal. The noise generated from the tip vortex became 200 Hz even if the number of blades was different. We clarified experimentally that the periodical noise due to the tip vortex became small according to the scale of the tip vortex
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Prediction on Broadband Noise of a Low Speed Propeller Fan Based on Amiet’s Trailing Edge Noise Model
Graduate School of Engineering Nagasaki University, 2013Co-Authors: 佐々木 壮一, 村上 寛明, 鳥瀬 一貴, 坂田 涼Abstract:Recent years, the trailing-edge noise model proposed by Prof. Michel Roger et al. in 2005 is utilized in the field of the aerodynamic noise prediction. In this report, the analytical theory is explained focusing on the mathematical description about the back-scattering model. Moreover, the prediction on the broadband noise spectra generated by a Propeller Fan with the semi-empirical models of the flow regime is discussed. The radiation integral of the disturbance pressure on the blade wall is given by the Amiet's model which is the scattering equivalent sources as if the airfoil were infinite in the upstream direction; the Corcos' model is employed for the span-wise correlation length. Furthermore, the wall pressure spectrum of the Gliebe's model on the blade is used. It was clarified that the aerodynamic noise sources formed by the back-scattering of the disturbance in the vicinity of the trailing edge produce the broadband noise in the high frequency domain
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Study of Blade Tip Vortex and Aerodynamic Noise of a Propeller Fan (Influence of Axial-direction Relative Position)
Graduate School of Engineering Nagasaki University, 2013Co-Authors: 佐々木 壮一, 鳥瀬 一貴, 村上 寛明Abstract:The objective of this study is to clarify the relationship between the tip vortex and aerodynamic noise of an open type Propeller Fan operating at the vicinity of the maximum efficiency point. The influence of the internal flow on the aerodynamic noise is discussed with taking account of the axial direction relative position. In this experiment, when the relative position is 20 mm, the periodical noise at 200 Hz which is the low frequency side than that of the blade passing frequency became large. The periodical noise became the one of the important factors for increasing the Fan noise by 5dB. The periodical noise was generated by the interaction between the tip vortex and the partition of the Fan. It was clarified that when the wake formed the flow regime of the high specific speed type impeller the blade tip vortex noise was generated
Masahiro Inoue - One of the best experts on this subject based on the ideXlab platform.
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frequency characteristics of fluctuating pressure on rotor blade in a Propeller Fan
Jsme International Journal Series B-fluids and Thermal Engineering, 2003Co-Authors: Choonman Jang, Masato Furukawa, Masahiro InoueAbstract:A wavelet transform is introduced to analyze frequency characteristics of the fluctuating pressure on rotor blade in a Propeller Fan. The fluctuating pressure on the rotor blade is obtained by using the results of a large eddy simulation. The frequencies having high spectral peaks of the fluctuating pressure are determined by taking the time average of the local absolute modulus of the wavelet. The dominant frequency of the real-time pressure selected at the high pressure fluctuation region corresponds well to that of the fluctuating rotor torque and the experimental result of Fan noise. It is mainly generated due to the unsteady behavior of the vortical flow, such as the tip vortex and the leading edge separation vortex, in the Propeller Fan. A frequency in the separation bubble region on the suction surface is higher than that of the dominant frequency caused by the vortical flow.
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analysis of vortical flow field in a Propeller Fan by ldv measurements and les part i three dimensional vortical flow structures
Journal of Fluids Engineering-transactions of The Asme, 2001Co-Authors: Choonman Jang, Masato Furukawa, Masahiro InoueAbstract:Three-dimensional structures of the vortical flow field in a Propeller Fan with a shroud covering only the rear region of its rotor tip have been investigated by experimental analysis using laser Doppler velocimetry (LDV) measurements and by numerical analysis using a large eddy simulation (LES) in Part I of the present study. The Propeller Fan has a very complicated vortical flow field near the rotor tip compared with axial Fan and compressor rotors. It is found that three vortex structures are formed near the rotor tip: the tip vortex, the leading edge separation vortex, and the tip leakage vortex. The tip vortex is so strong that it dominates the flow field near the tip. Its formation starts from the blade tip suction side near the midchord. Even at the design condition the tip vortex convects nearly in the tangential direction, thus impinging on the pressure surface of the adjacent blade. The leading edge separation vortex develops close along the tip suction surface and disappears in the rear region of the rotor passage. The tip leakage vortex is so weak that it does not affect the flow field in the rotor.
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analysis of vortical flow field in a Propeller Fan by ldv measurements and les part ii unsteady nature of vortical flow structures due to tip vortex breakdown
Journal of Fluids Engineering-transactions of The Asme, 2001Co-Authors: Choonman Jang, Masato Furukawa, Masahiro InoueAbstract:The unsteady nature of vortex structures has been investigated by a large eddy simulation (LES) in a Propeller Fan with a shroud covering only the rear region of its rotor tip. The tip vortex plays a major role in the structure and unsteady behavior of the vortical flow in the Propeller Fan. The spiral-type breakdown of the tip vortex occurs near the midpitch, leading to significant changes in the nature of the tip vortex. The breakdown gives rise to large and cyclic movements of the tip vortex, so that the vortex impinges cyclically on the pressure surface of the adjacent blade. The movements of the tip vortex cause the leading edge separation vortex to oscillate in a cycle, but on a small scale. The movements of the vortex structures induce high-pressure fluctuations on the rotor blade and in the blade passage
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Noise Reduction by Controlling Tip Vortex in a Propeller Fan
JSME International Journal Series B, 2001Co-Authors: Choonman Jang, Masato Furukawa, Masahiro InoueAbstract:Two types of shroud for Propeller Fans were introduced to reduce the Fan noise by controlling the tip vortex of a Fan rotor. Three-dimensional vortical flow structures and velocity fluctuation near the Fan rotor tip have been investigated by experimental analyses using laser Doppler velocimetry (LDV). The tip vortex formed near the midchord of the rotor tip develops in the tangential direction. This tangential structure of the tip vortex induces an inward radial flow near the leading edge of the rotor tip and a reverse flow between the rotor tip and the shroud, causing a large blockage effect on the through flow (main flow) in the rotor. High velocity fluctuations are observed in the interference region between the tip vortex and the through flow. The shroud designed so as to diminish the reverse flow between the rotor tip and the shroud can decrease the blockage effect due to the tip vortex, which decelerates the through flow in the rotor, thus leading to the reduction in the Fan noise.
Choonman Jang - One of the best experts on this subject based on the ideXlab platform.
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frequency characteristics of fluctuating pressure on rotor blade in a Propeller Fan
Jsme International Journal Series B-fluids and Thermal Engineering, 2003Co-Authors: Choonman Jang, Masato Furukawa, Masahiro InoueAbstract:A wavelet transform is introduced to analyze frequency characteristics of the fluctuating pressure on rotor blade in a Propeller Fan. The fluctuating pressure on the rotor blade is obtained by using the results of a large eddy simulation. The frequencies having high spectral peaks of the fluctuating pressure are determined by taking the time average of the local absolute modulus of the wavelet. The dominant frequency of the real-time pressure selected at the high pressure fluctuation region corresponds well to that of the fluctuating rotor torque and the experimental result of Fan noise. It is mainly generated due to the unsteady behavior of the vortical flow, such as the tip vortex and the leading edge separation vortex, in the Propeller Fan. A frequency in the separation bubble region on the suction surface is higher than that of the dominant frequency caused by the vortical flow.
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analysis of vortical flow field in a Propeller Fan by ldv measurements and les part i three dimensional vortical flow structures
Journal of Fluids Engineering-transactions of The Asme, 2001Co-Authors: Choonman Jang, Masato Furukawa, Masahiro InoueAbstract:Three-dimensional structures of the vortical flow field in a Propeller Fan with a shroud covering only the rear region of its rotor tip have been investigated by experimental analysis using laser Doppler velocimetry (LDV) measurements and by numerical analysis using a large eddy simulation (LES) in Part I of the present study. The Propeller Fan has a very complicated vortical flow field near the rotor tip compared with axial Fan and compressor rotors. It is found that three vortex structures are formed near the rotor tip: the tip vortex, the leading edge separation vortex, and the tip leakage vortex. The tip vortex is so strong that it dominates the flow field near the tip. Its formation starts from the blade tip suction side near the midchord. Even at the design condition the tip vortex convects nearly in the tangential direction, thus impinging on the pressure surface of the adjacent blade. The leading edge separation vortex develops close along the tip suction surface and disappears in the rear region of the rotor passage. The tip leakage vortex is so weak that it does not affect the flow field in the rotor.
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analysis of vortical flow field in a Propeller Fan by ldv measurements and les part ii unsteady nature of vortical flow structures due to tip vortex breakdown
Journal of Fluids Engineering-transactions of The Asme, 2001Co-Authors: Choonman Jang, Masato Furukawa, Masahiro InoueAbstract:The unsteady nature of vortex structures has been investigated by a large eddy simulation (LES) in a Propeller Fan with a shroud covering only the rear region of its rotor tip. The tip vortex plays a major role in the structure and unsteady behavior of the vortical flow in the Propeller Fan. The spiral-type breakdown of the tip vortex occurs near the midpitch, leading to significant changes in the nature of the tip vortex. The breakdown gives rise to large and cyclic movements of the tip vortex, so that the vortex impinges cyclically on the pressure surface of the adjacent blade. The movements of the tip vortex cause the leading edge separation vortex to oscillate in a cycle, but on a small scale. The movements of the vortex structures induce high-pressure fluctuations on the rotor blade and in the blade passage
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Noise Reduction by Controlling Tip Vortex in a Propeller Fan
JSME International Journal Series B, 2001Co-Authors: Choonman Jang, Masato Furukawa, Masahiro InoueAbstract:Two types of shroud for Propeller Fans were introduced to reduce the Fan noise by controlling the tip vortex of a Fan rotor. Three-dimensional vortical flow structures and velocity fluctuation near the Fan rotor tip have been investigated by experimental analyses using laser Doppler velocimetry (LDV). The tip vortex formed near the midchord of the rotor tip develops in the tangential direction. This tangential structure of the tip vortex induces an inward radial flow near the leading edge of the rotor tip and a reverse flow between the rotor tip and the shroud, causing a large blockage effect on the through flow (main flow) in the rotor. High velocity fluctuations are observed in the interference region between the tip vortex and the through flow. The shroud designed so as to diminish the reverse flow between the rotor tip and the shroud can decrease the blockage effect due to the tip vortex, which decelerates the through flow in the rotor, thus leading to the reduction in the Fan noise.
村上 寛明 - One of the best experts on this subject based on the ideXlab platform.
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Study of Periodical Aerodynamic Noise Generated due to Tip Vortex of a Propeller Fan (Influence on Number of Blades)
Graduate School of Engineering Nagasaki University, 2014Co-Authors: 佐々木 壮一, 村上 寛明Abstract:In order to discuss the major factor on the noise characteristics of a Propeller Fan, the influence of the number of blades on the periodical Fan noise generated due to the tip vortex is analyzed. The influence of the tip vortex on the Fan noise is argued by the measured internal flow. For the analysis of the structure on the mean flow in the blade passage, the phase of the unsteady signal of the wake is locked by the trigger signal synchronized with the rotation signal. The noise generated from the tip vortex became 200 Hz even if the number of blades was different. We clarified experimentally that the periodical noise due to the tip vortex became small according to the scale of the tip vortex
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Prediction on Broadband Noise of a Low Speed Propeller Fan Based on Amiet’s Trailing Edge Noise Model
Graduate School of Engineering Nagasaki University, 2013Co-Authors: 佐々木 壮一, 村上 寛明, 鳥瀬 一貴, 坂田 涼Abstract:Recent years, the trailing-edge noise model proposed by Prof. Michel Roger et al. in 2005 is utilized in the field of the aerodynamic noise prediction. In this report, the analytical theory is explained focusing on the mathematical description about the back-scattering model. Moreover, the prediction on the broadband noise spectra generated by a Propeller Fan with the semi-empirical models of the flow regime is discussed. The radiation integral of the disturbance pressure on the blade wall is given by the Amiet's model which is the scattering equivalent sources as if the airfoil were infinite in the upstream direction; the Corcos' model is employed for the span-wise correlation length. Furthermore, the wall pressure spectrum of the Gliebe's model on the blade is used. It was clarified that the aerodynamic noise sources formed by the back-scattering of the disturbance in the vicinity of the trailing edge produce the broadband noise in the high frequency domain
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Study of Blade Tip Vortex and Aerodynamic Noise of a Propeller Fan (Influence of Axial-direction Relative Position)
Graduate School of Engineering Nagasaki University, 2013Co-Authors: 佐々木 壮一, 鳥瀬 一貴, 村上 寛明Abstract:The objective of this study is to clarify the relationship between the tip vortex and aerodynamic noise of an open type Propeller Fan operating at the vicinity of the maximum efficiency point. The influence of the internal flow on the aerodynamic noise is discussed with taking account of the axial direction relative position. In this experiment, when the relative position is 20 mm, the periodical noise at 200 Hz which is the low frequency side than that of the blade passing frequency became large. The periodical noise became the one of the important factors for increasing the Fan noise by 5dB. The periodical noise was generated by the interaction between the tip vortex and the partition of the Fan. It was clarified that when the wake formed the flow regime of the high specific speed type impeller the blade tip vortex noise was generated
