Flow visualization and hot-wire measurement techniques were combined to investigate the influence of the size and number of tabs on jet flow field and vortex structure generation mechanism. Streamwise vortices generat...Flow visualization and hot-wire measurement techniques were combined to investigate the influence of the size and number of tabs on jet flow field and vortex structure generation mechanism. Streamwise vortices generated by the tabs of different sizes and numbers were observed from the flow visualization images. Combined with flow visualization, hot-wire measurement gave a quantitative insight of the effect of various tabbed jet flows. Instantaneous two-component velocity signals (longitudinal and transverse velocity components) at different cross sections along radius direction and streamwise direction with different tabbed jet nozzles were measured using hot-wire anemometer. Average flow field parameters of tabbed jet flow such as mean velocity, tur-bulence intensity, vorticity were analyzed and the effects of tabs with different sizes and numbers were compared with that of circular no-tab jet flow. It is revealed that the generation of a series of counter-rotating quasi-streamwise vortices, azimuthal vortices and double-row azi-muthal vortex are the reasons for mixing enhancement of tabbed turbulent jet flow.展开更多
A flow control system that combined steady Vortex Generator Jets and Deflected Trailing-edge(VGJs-DT) to decrease the low pressure turbine(LPT) blade numbers was presented.The effects of VGJs-DT on energy loss and flo...A flow control system that combined steady Vortex Generator Jets and Deflected Trailing-edge(VGJs-DT) to decrease the low pressure turbine(LPT) blade numbers was presented.The effects of VGJs-DT on energy loss and flow of low solidity low pressure turbine(LSLPT) cascades were studied.VGJs-DT was found to decrease the energy loss of LSLPT cascade and increase the flow turning angle.VGJs-DT decreased the solidity by 12.5%without a significant increase in energy loss.VGJs-DT was more effective than steady VGJs.VGJs-DT decreased the energy loss and increased the flow angle of the LSLPT cascade with steady VGJs.VGJs-DT can use 50%less mass flow than steady VGJs to inhibit the flow separation in the LSLPT cascade.The deflected trailing edge enhanced the ability of steady VGJs to resist flow separation.Overall,VGJs-DT can be used to control flow separation in LPT cascade and reduce the blade numbers of low pressure turbine stage.展开更多
基金National Natural Science Foundation of China (No.10472081)Program for New Century Excellent Talents in Universities of Minis-try of Education of China and Plan of Tianjin Science and Technology Development (No.06TXTJJC13800)
文摘Flow visualization and hot-wire measurement techniques were combined to investigate the influence of the size and number of tabs on jet flow field and vortex structure generation mechanism. Streamwise vortices generated by the tabs of different sizes and numbers were observed from the flow visualization images. Combined with flow visualization, hot-wire measurement gave a quantitative insight of the effect of various tabbed jet flows. Instantaneous two-component velocity signals (longitudinal and transverse velocity components) at different cross sections along radius direction and streamwise direction with different tabbed jet nozzles were measured using hot-wire anemometer. Average flow field parameters of tabbed jet flow such as mean velocity, tur-bulence intensity, vorticity were analyzed and the effects of tabs with different sizes and numbers were compared with that of circular no-tab jet flow. It is revealed that the generation of a series of counter-rotating quasi-streamwise vortices, azimuthal vortices and double-row azi-muthal vortex are the reasons for mixing enhancement of tabbed turbulent jet flow.
基金supported by the National Foundation for Innovative Research Groups of China(Grant No.51421063)
文摘A flow control system that combined steady Vortex Generator Jets and Deflected Trailing-edge(VGJs-DT) to decrease the low pressure turbine(LPT) blade numbers was presented.The effects of VGJs-DT on energy loss and flow of low solidity low pressure turbine(LSLPT) cascades were studied.VGJs-DT was found to decrease the energy loss of LSLPT cascade and increase the flow turning angle.VGJs-DT decreased the solidity by 12.5%without a significant increase in energy loss.VGJs-DT was more effective than steady VGJs.VGJs-DT decreased the energy loss and increased the flow angle of the LSLPT cascade with steady VGJs.VGJs-DT can use 50%less mass flow than steady VGJs to inhibit the flow separation in the LSLPT cascade.The deflected trailing edge enhanced the ability of steady VGJs to resist flow separation.Overall,VGJs-DT can be used to control flow separation in LPT cascade and reduce the blade numbers of low pressure turbine stage.
