Large eddy simulation of saw tooth plasma actuator for improving film cooling efficiency

2017 ◽  
Vol 231 (5) ◽  
pp. 357-370 ◽  
Author(s):  
Guozhan Li ◽  
Jianyang Yu ◽  
Fu Chen ◽  
Huaping Liu ◽  
Yanping Song ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Flat Plate ◽  
Film Cooling ◽  
Three Dimensional ◽  
Plasma Actuator ◽  
Cooling Efficiency ◽  
Flow Topology ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Film Cooling Efficiency

This paper presents results on a saw tooth plasma actuator for the inducement of flow topology and the improvement of flat plate film cooling efficiency. A phenomenological plasma model is constructed to generate the three-dimensional plasma force vectors of the saw tooth plasma actuator. The dynamics of airflow induced by the saw tooth plasma actuator on a flat plate in quiescent air are numerically investigated. The results show that the saw tooth plasma actuator pushes the fluids in all three directions and induces a three-dimensional jet flow with counter rotating streamwise oriented vortices that propagate downstream. The flow field characteristics of both cylindrical hole with and without the saw tooth plasma actuator are studied by large eddy simulation, and a comparison is made. The saw tooth plasma actuator improves the cold jet adherent performance and promotes the spanwise spreading rate of the coolant. Meanwhile, the streamwise vortices induced by the saw tooth plasma actuator suppress the development of counter-rotating vortex pair, thus delaying the diffusion of coolant in the crossflow. Accordingly, the centerline cooling efficiency and the spanwise-averaged cooling efficiency are improved by 36% and 144% at x/ d = 15, compared with the baseline case without the saw tooth plasma actuator.

Large Eddy Simulation of Film Cooling over a Flat Plate in Supersonic flow

2020 ◽  
pp. 1-29
Author(s):  
Hitesh Sharma ◽  
Dushyant Singh ◽  
Ashutosh Kumar Singh
Keyword(s):  
Heat Transfer ◽  
Supersonic Flow ◽  
Large Eddy Simulation ◽  
Flat Plate ◽  
Film Cooling ◽  
Cooling Effectiveness ◽  
Potential Core ◽  
Film Cooling Effectiveness ◽  
Eddy Simulation ◽  
Large Eddy

Abstract In the present work, Large Eddy Simulation (LES) was performed to access the film cooling performance in the supersonic flow over a flat plate with a perpendicular slot injection configuration. The study was carried out for three mainstream Mach No.; Mα = 1.2, 2.67, 3.3 and three coolant stream Mach No.; 0.05, 0.1, 0.15. In supersonic flow, temperature rise inside the boundary layer is a major issue considering it causes high rates of heat transfer to the coolant film. To select a suitable LES Sub-Grid Scale (SGS) model, LES results obtained from the present study using the LES Sub-Grid Scale (SGS) models such as Smagorinky- Lilly, Wale, and WMLES models were compared with DNS results available for flow and heat transfer. The parametric study showed that the higher mainstream Mach No. caused increased wall temperature and reduced effectiveness. The film cooling effectiveness appeared to reduce almost by 10% when the mainstream Mach No. is increased from 1.2 to 2.67, however, no apparent difference was observed in effectiveness between the mainstream Mach No. 2.67 and 3.3. It was found that doubling and tripling the coolant stream Mach No. from 0.05 to 0.1 and 0.15, the length of potential core region also doubled and tripled respectively from 4 X/S to 8 X/S and 13 X/S and hence significant improvement in the film cooling effectiveness was observed.

Large Eddy Simulation of the Elliptic Jets in Film Cooling Controlled by Dielectric Barrier Discharge Plasma Actuators With an Improved Model

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Jianyang Yu ◽  
Zhao Wang ◽  
Fu Chen ◽  
Guojun Yan ◽  
Cong Wang
Keyword(s):  
Large Eddy Simulation ◽  
Dielectric Barrier Discharge ◽  
Film Cooling ◽  
Barrier Discharge ◽  
Plasma Actuator ◽  
Streamwise Vortices ◽  
Dbd Plasma ◽  
Dielectric Barrier ◽  
Eddy Simulation ◽  
Large Eddy

The dielectric barrier discharge (DBD) plasma actuator, in which electrodes are asymmetric arranged, has already demonstrated its ability in flow control. In the present work, the configuration of DBD plasma actuator defined as DBD-vortex generator (VGs), which can induce streamwise vortices, has been employed in the flow control of the inclined jet in crossflow. The coherent turbulent structures around the cooling hole are examined by the large eddy simulation (LES) method with the improved plasma model. The mechanism of coherent structure controlled by the DBD-VGs is also elucidated in the processes of parametric study with the actuation conditions. The calculation results show that the DBD-VGs provides us an effective approach to further enhance the performance of the film cooling. When it is applied into the flow, symmetrical streamwise vortices are induced to break down the coherent vortex structure, leading to more coolant gathered on the surface, especially at the lateral area of the coolant jet. What is more, an overall improvement of the film cooling performance can be obtained when the actuation strength is strong enough.

J051021 Large-eddy Simulation of Film Cooling Flow on Flat Plate

2012 ◽  
Vol 2012 (0) ◽  
pp. _J051021-1-_J051021-4
Author(s):  
Eiji SAKAI ◽  
Toshihiko TAKAHASHI ◽  
Hiroaki WATANABE
Keyword(s):  
Large Eddy Simulation ◽  
Flat Plate ◽  
Film Cooling ◽  
Cooling Flow ◽  
Eddy Simulation ◽  
Large Eddy
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