The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Kyohei Tajiri - One of the best experts on this subject based on the ideXlab platform.
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six degrees of freedom numerical simulation of tilt Rotor Plane
International Conference on Computational Science, 2019Co-Authors: Ayato Takii, Masashi Yamakawa, Shinichi Asao, Kyohei TajiriAbstract:Six degrees of freedom coupled simulation is presented for a tilt-Rotor Plane represented by V-22 Osprey. The Moving Computational Domain (MCD) method is used to compute a flow field around aircraft and the movement of the body with high accuracy. This method enables to move a Plane through space without restriction of computational ranges. Therefore it is different from computation of such the flows by using conventional methods that calculate a flow field around a static body placing it in a uniform flow like a wind tunnel. To calculate with high accuracy, no simplification for simulating propeller was used. Fluid flows are created only by moving boundaries of an object. A tilt-Rotor Plane has a hovering function like a helicopter by turning axes of Rotor toward the sky during takeoff or landing. On the other hand in flight, it behaves as a reciprocating aircraft by turning axes of Rotor forward. To perform such two flight modes in the simulation, multi-axis sliding mesh approach was proposed which is a computational technique to enable us to deal with multiple axes of different direction. Moreover, using in combination with the MCD method, the approach has been able to be applied to the simulation which has more complicated motions of boundaries.
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ICCS (1) - Six Degrees of Freedom Numerical Simulation of Tilt-Rotor Plane.
Lecture Notes in Computer Science, 2019Co-Authors: Ayato Takii, Masashi Yamakawa, Shinichi Asao, Kyohei TajiriAbstract:Six degrees of freedom coupled simulation is presented for a tilt-Rotor Plane represented by V-22 Osprey. The Moving Computational Domain (MCD) method is used to compute a flow field around aircraft and the movement of the body with high accuracy. This method enables to move a Plane through space without restriction of computational ranges. Therefore it is different from computation of such the flows by using conventional methods that calculate a flow field around a static body placing it in a uniform flow like a wind tunnel. To calculate with high accuracy, no simplification for simulating propeller was used. Fluid flows are created only by moving boundaries of an object. A tilt-Rotor Plane has a hovering function like a helicopter by turning axes of Rotor toward the sky during takeoff or landing. On the other hand in flight, it behaves as a reciprocating aircraft by turning axes of Rotor forward. To perform such two flight modes in the simulation, multi-axis sliding mesh approach was proposed which is a computational technique to enable us to deal with multiple axes of different direction. Moreover, using in combination with the MCD method, the approach has been able to be applied to the simulation which has more complicated motions of boundaries.
Damiano Casalino - One of the best experts on this subject based on the ideXlab platform.
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On the effect of the tip-clearance ratio on the aeroacoustics of a diffuser-augmented wind turbine
Renewable Energy, 2020Co-Authors: Francesco Avallone, Daniele Ragni, Damiano CasalinoAbstract:Lattice-Boltzmann Very-Large-Eddy Simulations of two Diffuser-Augmented Wind Turbines are carried out to investigate the effect of the tip-clearance (TC) ratio on both the flow field and the far-field noise. The DonQi® wind turbine, a three blades ducted Rotor with nominal TC of 2.5%, is chosen as reference test case. The second configuration has TC equal to 0.7%. The latter shows flow separation on the diffuser suction side causing lower velocity at the Rotor Plane and a reduction of 5% of the thrust coefficient. Flow separation is associated with the break down of the tip vortex immediately after the Rotor Plane. The TC has an effect on the far-field noise. For angles between 60∘ and 120∘, where 0∘ corresponds to the axial upstream direction, the blade tonal noise is the dominant source. For other angular directions, noise increase is found for the smaller TC and it associated to an additional noise source located into the gap that can be modeled as a monopole source. It causes an increase of broadband noise at frequencies higher than the third blade passing frequency and tonal peaks at frequencies equal to 4.5 times the blade passing frequency and higher harmonics.
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On the Effect of the Tip Clearance on the Aerodynamic and Aeroacoustics of a Diffuser-Augmented Wind Turbine
AIAA Scitech 2019 Forum, 2019Co-Authors: Francesco Avallone, Damiano Casalino, Daniele RagniAbstract:A computational study of two Diffuser-Augmented Wind Turbines (DAWTs) is carried out to investigate both the hydrodynamic flow field and the far-field noise. The two configurations differ for the tip-clearance ratio, defined as the ratio between the tip clearance and the Rotor radius. The DonQi® wind turbine, a three blades ducted Rotor, is adopted as baseline configuration because of the availability of reference data. It has a tip-clearance ratio of 2.5%. The second configuration is obtained from the first one by elongating the Rotor radius such to force the interaction between the turbulent boundary layer, developing over the suction side of the diffuser, and the tip of the blades, thus resulting in a tip-clearance ratio of 0.7%. The Rotor with the longer blades shows a reduction of the thrust coefficient because of the lower lift generated by the diffuser that results in a lower axial velocity at the Rotor Plane. It is shown that this is caused by the smaller tip gap that forces the break down of the Rotor tip vortex in smaller turbulent structures immediately after the Rotor Plane and that induces earlier flow separation along the suction side of the diffuser. The tip-clearance ratio has also a strong effect on the far-field noise. For angles between 60◦ and 120◦, where 0◦ corresponds to the axial upstream direction, the blade tonal noise, at frequency equal to the blade passing frequency and higher harmonics, is the dominant source. For other angular directions, noise increase is found for the smaller tip-clearance ratio case associated to an additional noise source, that becomes dominant, linked to an increase of the energy content of velocity fluctuations in the gap region. This noise source, that can be modeled as a monopole source located in the gap, causes an increase of broadband noise at frequencies higher than the third blade passing frequency and a tonal peak at a frequency equal to 4.5 times the blade passing frequency and higher harmonics.
Francesco Avallone - One of the best experts on this subject based on the ideXlab platform.
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On the effect of the tip-clearance ratio on the aeroacoustics of a diffuser-augmented wind turbine
Renewable Energy, 2020Co-Authors: Francesco Avallone, Daniele Ragni, Damiano CasalinoAbstract:Lattice-Boltzmann Very-Large-Eddy Simulations of two Diffuser-Augmented Wind Turbines are carried out to investigate the effect of the tip-clearance (TC) ratio on both the flow field and the far-field noise. The DonQi® wind turbine, a three blades ducted Rotor with nominal TC of 2.5%, is chosen as reference test case. The second configuration has TC equal to 0.7%. The latter shows flow separation on the diffuser suction side causing lower velocity at the Rotor Plane and a reduction of 5% of the thrust coefficient. Flow separation is associated with the break down of the tip vortex immediately after the Rotor Plane. The TC has an effect on the far-field noise. For angles between 60∘ and 120∘, where 0∘ corresponds to the axial upstream direction, the blade tonal noise is the dominant source. For other angular directions, noise increase is found for the smaller TC and it associated to an additional noise source located into the gap that can be modeled as a monopole source. It causes an increase of broadband noise at frequencies higher than the third blade passing frequency and tonal peaks at frequencies equal to 4.5 times the blade passing frequency and higher harmonics.
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On the Effect of the Tip Clearance on the Aerodynamic and Aeroacoustics of a Diffuser-Augmented Wind Turbine
AIAA Scitech 2019 Forum, 2019Co-Authors: Francesco Avallone, Damiano Casalino, Daniele RagniAbstract:A computational study of two Diffuser-Augmented Wind Turbines (DAWTs) is carried out to investigate both the hydrodynamic flow field and the far-field noise. The two configurations differ for the tip-clearance ratio, defined as the ratio between the tip clearance and the Rotor radius. The DonQi® wind turbine, a three blades ducted Rotor, is adopted as baseline configuration because of the availability of reference data. It has a tip-clearance ratio of 2.5%. The second configuration is obtained from the first one by elongating the Rotor radius such to force the interaction between the turbulent boundary layer, developing over the suction side of the diffuser, and the tip of the blades, thus resulting in a tip-clearance ratio of 0.7%. The Rotor with the longer blades shows a reduction of the thrust coefficient because of the lower lift generated by the diffuser that results in a lower axial velocity at the Rotor Plane. It is shown that this is caused by the smaller tip gap that forces the break down of the Rotor tip vortex in smaller turbulent structures immediately after the Rotor Plane and that induces earlier flow separation along the suction side of the diffuser. The tip-clearance ratio has also a strong effect on the far-field noise. For angles between 60◦ and 120◦, where 0◦ corresponds to the axial upstream direction, the blade tonal noise, at frequency equal to the blade passing frequency and higher harmonics, is the dominant source. For other angular directions, noise increase is found for the smaller tip-clearance ratio case associated to an additional noise source, that becomes dominant, linked to an increase of the energy content of velocity fluctuations in the gap region. This noise source, that can be modeled as a monopole source located in the gap, causes an increase of broadband noise at frequencies higher than the third blade passing frequency and a tonal peak at a frequency equal to 4.5 times the blade passing frequency and higher harmonics.
Ayato Takii - One of the best experts on this subject based on the ideXlab platform.
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six degrees of freedom numerical simulation of tilt Rotor Plane
International Conference on Computational Science, 2019Co-Authors: Ayato Takii, Masashi Yamakawa, Shinichi Asao, Kyohei TajiriAbstract:Six degrees of freedom coupled simulation is presented for a tilt-Rotor Plane represented by V-22 Osprey. The Moving Computational Domain (MCD) method is used to compute a flow field around aircraft and the movement of the body with high accuracy. This method enables to move a Plane through space without restriction of computational ranges. Therefore it is different from computation of such the flows by using conventional methods that calculate a flow field around a static body placing it in a uniform flow like a wind tunnel. To calculate with high accuracy, no simplification for simulating propeller was used. Fluid flows are created only by moving boundaries of an object. A tilt-Rotor Plane has a hovering function like a helicopter by turning axes of Rotor toward the sky during takeoff or landing. On the other hand in flight, it behaves as a reciprocating aircraft by turning axes of Rotor forward. To perform such two flight modes in the simulation, multi-axis sliding mesh approach was proposed which is a computational technique to enable us to deal with multiple axes of different direction. Moreover, using in combination with the MCD method, the approach has been able to be applied to the simulation which has more complicated motions of boundaries.
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ICCS (1) - Six Degrees of Freedom Numerical Simulation of Tilt-Rotor Plane.
Lecture Notes in Computer Science, 2019Co-Authors: Ayato Takii, Masashi Yamakawa, Shinichi Asao, Kyohei TajiriAbstract:Six degrees of freedom coupled simulation is presented for a tilt-Rotor Plane represented by V-22 Osprey. The Moving Computational Domain (MCD) method is used to compute a flow field around aircraft and the movement of the body with high accuracy. This method enables to move a Plane through space without restriction of computational ranges. Therefore it is different from computation of such the flows by using conventional methods that calculate a flow field around a static body placing it in a uniform flow like a wind tunnel. To calculate with high accuracy, no simplification for simulating propeller was used. Fluid flows are created only by moving boundaries of an object. A tilt-Rotor Plane has a hovering function like a helicopter by turning axes of Rotor toward the sky during takeoff or landing. On the other hand in flight, it behaves as a reciprocating aircraft by turning axes of Rotor forward. To perform such two flight modes in the simulation, multi-axis sliding mesh approach was proposed which is a computational technique to enable us to deal with multiple axes of different direction. Moreover, using in combination with the MCD method, the approach has been able to be applied to the simulation which has more complicated motions of boundaries.
Daniele Ragni - One of the best experts on this subject based on the ideXlab platform.
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On the effect of the tip-clearance ratio on the aeroacoustics of a diffuser-augmented wind turbine
Renewable Energy, 2020Co-Authors: Francesco Avallone, Daniele Ragni, Damiano CasalinoAbstract:Lattice-Boltzmann Very-Large-Eddy Simulations of two Diffuser-Augmented Wind Turbines are carried out to investigate the effect of the tip-clearance (TC) ratio on both the flow field and the far-field noise. The DonQi® wind turbine, a three blades ducted Rotor with nominal TC of 2.5%, is chosen as reference test case. The second configuration has TC equal to 0.7%. The latter shows flow separation on the diffuser suction side causing lower velocity at the Rotor Plane and a reduction of 5% of the thrust coefficient. Flow separation is associated with the break down of the tip vortex immediately after the Rotor Plane. The TC has an effect on the far-field noise. For angles between 60∘ and 120∘, where 0∘ corresponds to the axial upstream direction, the blade tonal noise is the dominant source. For other angular directions, noise increase is found for the smaller TC and it associated to an additional noise source located into the gap that can be modeled as a monopole source. It causes an increase of broadband noise at frequencies higher than the third blade passing frequency and tonal peaks at frequencies equal to 4.5 times the blade passing frequency and higher harmonics.
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On the Effect of the Tip Clearance on the Aerodynamic and Aeroacoustics of a Diffuser-Augmented Wind Turbine
AIAA Scitech 2019 Forum, 2019Co-Authors: Francesco Avallone, Damiano Casalino, Daniele RagniAbstract:A computational study of two Diffuser-Augmented Wind Turbines (DAWTs) is carried out to investigate both the hydrodynamic flow field and the far-field noise. The two configurations differ for the tip-clearance ratio, defined as the ratio between the tip clearance and the Rotor radius. The DonQi® wind turbine, a three blades ducted Rotor, is adopted as baseline configuration because of the availability of reference data. It has a tip-clearance ratio of 2.5%. The second configuration is obtained from the first one by elongating the Rotor radius such to force the interaction between the turbulent boundary layer, developing over the suction side of the diffuser, and the tip of the blades, thus resulting in a tip-clearance ratio of 0.7%. The Rotor with the longer blades shows a reduction of the thrust coefficient because of the lower lift generated by the diffuser that results in a lower axial velocity at the Rotor Plane. It is shown that this is caused by the smaller tip gap that forces the break down of the Rotor tip vortex in smaller turbulent structures immediately after the Rotor Plane and that induces earlier flow separation along the suction side of the diffuser. The tip-clearance ratio has also a strong effect on the far-field noise. For angles between 60◦ and 120◦, where 0◦ corresponds to the axial upstream direction, the blade tonal noise, at frequency equal to the blade passing frequency and higher harmonics, is the dominant source. For other angular directions, noise increase is found for the smaller tip-clearance ratio case associated to an additional noise source, that becomes dominant, linked to an increase of the energy content of velocity fluctuations in the gap region. This noise source, that can be modeled as a monopole source located in the gap, causes an increase of broadband noise at frequencies higher than the third blade passing frequency and a tonal peak at a frequency equal to 4.5 times the blade passing frequency and higher harmonics.
