Numerical Study On The Effect Of The Vortex Induced By DBD Plasma On Flim Cooling Structure

Film cooling has been widely and deeply studied as an important cooling method for turbomachine with high temperature blades.The inlet temperature of tuebine is increasing with the continuous development of aero-engines and traditional film cooling technology won't be able to meet the cooling needs of high-performance engines in the furture,therefore,it is urgent to develop high-efficiency film cooling technology.As a new type of active flow control technology,flow control technology with plasma has received extensive attention in recent years.The use of DBD(Dielectri Barrier Discharge)plasma aerodynamic excitation can improve the field structure of flow,thus providing a new cooling efficiency for the improvement of traditional film cooling technology.In this paper,based on the standard Shyy plasma phenomenological model,a dual plasma actuator model arranged opposite to the flow direction is established,and the RANS is used for numerical simulation calculation.Firstly,the analysis of film cooling on flat has carried out that there is a counter rotating vortex pair(CRVP)in the film cooling flow field.The vortex has a lifting effect to keep the cooling airflow away from the high temperature wall and the dual plasma actuator can induce a new strip of pair vortex which has an opposite rotating direction of CRVP,thereby weakening the strength of the CRVP and improving the ability of near to the wall of cooling airflow.Then,through the study of the cooling efficiency distribution on the wall of flat,it's found that the momentum injection effect of the plasma actuator can increase the range of the film cooling efficiency along the flat and improve the cooling efficiency of the area behind the hole.Finally,the effect of parameter of actuator changes in film cooling has been studied by changing the intensity and the spacing of expose electric of the dual actuator.The results show that the higher intensity is,the larger the range of the cooling airflow acting on spanwise of flat is,and also the larger the value of cooling efficiency is.The larger the electrode spacing is,the wider the range of the low temperature zone is,but the air film cooling efficiency near the centerline is slightly reduced.Based on the research of film cooling on flat,the practical application effect of the plasma model on the C3 X blade is studied in depth.The difference between the structure of the film cooling flow field in turbine and the structure of different blowing ratios and the influence of the intensity of actuator on the induced flow field of the film cooling are analyzed.Studies have shown that the effect of the CRVP and the favorable pressure gradient causes the cooling airflow to not completely adhere to the blade surface in the area behind the hole,and is ruptured by the adverse pressure gradient and the CRVP at the reattachment position.The influence of the blowing ratio on the flow field of the cooling gas in turbine cascade is mainly reflected in the state between wall and cooling airflow and the capability of the cooling airflow spread along the flow direction.The influence of the intensity of actuator is mainly in the range of 60% L at the trailing edge of the film hole.The larger the intensity is,the higher the efficiency of the region.But at higher intensity,the gain from increasing the intensity again will be relatively small.