An improved smoke-wire flow visualization technique using a large capacitor as the power source was proposed. Electric current discharged from capacitors was used to heat a fine metal wire suspended in the flow field....An improved smoke-wire flow visualization technique using a large capacitor as the power source was proposed. Electric current discharged from capacitors was used to heat a fine metal wire suspended in the flow field. The oil droplets attached to the wire were vaporized and smoke filaments followed the flow motions. A digital camera was used to record the images of the smoke filaments. The actions of discharging and camera shutter were triggered by signals from a microcontroller to ensure the accurate timing. Clear images of the streaklines were captured at a freestream velocity up to 12.9 m/s, much higher than the limits of the existing techniques.展开更多
The oscillation characteristics of two planar opposed jets were studied by using high-speed camera,smoke wire visualization and hot-wire anemometry(HWA).The oscillation periods of two planar opposed jets at different ...The oscillation characteristics of two planar opposed jets were studied by using high-speed camera,smoke wire visualization and hot-wire anemometry(HWA).The oscillation periods of two planar opposed jets at different nozzle separations and exit nozzle velocities were studied.The results showed two models of instabilities:streamwise quasi-periodic oscillation model and deflection oscillation model.The oscillation model was mainly streamwise quasi-periodic oscillation model at L<5H(where L was the nozzle separation and H was the nozzle slot height),and it was mainly deflection oscillation model at L>5H.The deflection oscillation model had a stable period which decreased with increasing normalized nozzle separation.展开更多
基金supported by the National Natural Science Foundation of China (91752101 and 11572078)
文摘An improved smoke-wire flow visualization technique using a large capacitor as the power source was proposed. Electric current discharged from capacitors was used to heat a fine metal wire suspended in the flow field. The oil droplets attached to the wire were vaporized and smoke filaments followed the flow motions. A digital camera was used to record the images of the smoke filaments. The actions of discharging and camera shutter were triggered by signals from a microcontroller to ensure the accurate timing. Clear images of the streaklines were captured at a freestream velocity up to 12.9 m/s, much higher than the limits of the existing techniques.
文摘The oscillation characteristics of two planar opposed jets were studied by using high-speed camera,smoke wire visualization and hot-wire anemometry(HWA).The oscillation periods of two planar opposed jets at different nozzle separations and exit nozzle velocities were studied.The results showed two models of instabilities:streamwise quasi-periodic oscillation model and deflection oscillation model.The oscillation model was mainly streamwise quasi-periodic oscillation model at L<5H(where L was the nozzle separation and H was the nozzle slot height),and it was mainly deflection oscillation model at L>5H.The deflection oscillation model had a stable period which decreased with increasing normalized nozzle separation.
