An investigation made on the rotor blade tip vortex through use of a Three Dimensional Laser Doppler Velocimetry(3D LDV) is described. The experiment is conducted with a 2 m in diameter model helicopter rotor. By a ...An investigation made on the rotor blade tip vortex through use of a Three Dimensional Laser Doppler Velocimetry(3D LDV) is described. The experiment is conducted with a 2 m in diameter model helicopter rotor. By a series of measurements near blade tip, the velocity field near blade tip is documented, and through which, the tip vortex rollup and development are presented. The radial distribution of instantaneous velocities at various levels above and under the rotor disc is also measured in this investigation. Using this distribution, the influence of the tip vortex from the preceding blade on the follow up blade is discussed.展开更多
In this paper, recent measurements of tip vortex flow with and without cavitation carried out in Cavitation Mechanism Tunnel of China Ship Scientific Research Center（CSSRC） are presented. The elliptic hydrofoil with...In this paper, recent measurements of tip vortex flow with and without cavitation carried out in Cavitation Mechanism Tunnel of China Ship Scientific Research Center（CSSRC） are presented. The elliptic hydrofoil with section NACA 662-415 was adopted as test model. High-speed video（HSV） camera was used to visualize the trajectory of tip vortex core and the form of tip vortex cavitation（TVC） in different cavitation situations. Laser Doppler velocimetry（LDV） was employed to measure the tip vortex flow field in some typical sections along the vortex trajectory with the case of cavitation free. Stereo particle image velocimetry（SPIV） system was used to measure the velocity and vorticity distributions with and without cavitation. Series measurement results such as velocity and vorticity distributions, the trajectory of tip vortex core, the vortex core radius, cavity size and cavitation inception number were obtained. The results demonstrated that the minimum pressure coefficient in the vortex core obtained by flow field measurement was quite coincident with the tip vortex cavitation inception number obtained under the condition of high incoming velocity and low air content. And TVC would decrease the vortex strength comparing with the case without cavitation.展开更多
文摘An investigation made on the rotor blade tip vortex through use of a Three Dimensional Laser Doppler Velocimetry(3D LDV) is described. The experiment is conducted with a 2 m in diameter model helicopter rotor. By a series of measurements near blade tip, the velocity field near blade tip is documented, and through which, the tip vortex rollup and development are presented. The radial distribution of instantaneous velocities at various levels above and under the rotor disc is also measured in this investigation. Using this distribution, the influence of the tip vortex from the preceding blade on the follow up blade is discussed.
基金Project supported by the Key Project of National Natural Science Foundation of China(Grant No.11332009)
文摘In this paper, recent measurements of tip vortex flow with and without cavitation carried out in Cavitation Mechanism Tunnel of China Ship Scientific Research Center（CSSRC） are presented. The elliptic hydrofoil with section NACA 662-415 was adopted as test model. High-speed video（HSV） camera was used to visualize the trajectory of tip vortex core and the form of tip vortex cavitation（TVC） in different cavitation situations. Laser Doppler velocimetry（LDV） was employed to measure the tip vortex flow field in some typical sections along the vortex trajectory with the case of cavitation free. Stereo particle image velocimetry（SPIV） system was used to measure the velocity and vorticity distributions with and without cavitation. Series measurement results such as velocity and vorticity distributions, the trajectory of tip vortex core, the vortex core radius, cavity size and cavitation inception number were obtained. The results demonstrated that the minimum pressure coefficient in the vortex core obtained by flow field measurement was quite coincident with the tip vortex cavitation inception number obtained under the condition of high incoming velocity and low air content. And TVC would decrease the vortex strength comparing with the case without cavitation.
