| Corrugated surface is widely used as a thermal protection structure in a afterburner of military aeroengine.The installation of a porous corrugated surface on the afterburner can effectively improve the cooling efficiency of the heat shield.In order to explore the influence of structure and aerodynamic parameters on flow and heat transfer characteristics of heat shield.In this paper,the flow and heat transfer characteristics of corrugated surface are studied by numerical simulation and experiment.Firstly,an experimental system for the cooling characteristics of corrugated surface was constructed,the effects of pore size,pore ratio and non-uniform arrangement of film holes on wall temperature and overall cooling efficiency of heat shield were studied.The experimental results show that the temperature is serrated on the wall.The aperture d/l=0.0138 has the best cooling effect on the transverse corrugated heat shield,the cooling efficiency tends to a certain value and the corresponding streamwise spacing is shortest.With the same cooling flow rate per unit area,and the opening ratio ?=4.90% is the best for the wall surface of the heat shield.For the arrangement of non-uniform holes,the reduction of the secondary airflow side hole row has a significant effect on the heat exchange capacity of the longitudinal corrugated heat shield wall.Secondly,the effects of blowing ratio,aperture,opening ratio,hole arrangement and corrugated center line on the flow and heat transfer characteristics of transverse heat shield at high cold air temperature were studied by numerical simulation.The calculation results show that the temperature of the peak at the same flow cross section is always higher than the trough with the blowing ratio changing,and the temperature is serrated on the wall surface,and the best blowing ratio is M=2.0.When the cooling flow rate per unit area is the same and the aperture d/l=0.0138,the cooling efficiency tends to a flat level and the corresponding streamwise spacing is shortest,and the cooling efficiency with ?=3.14% is bigger.Similarly,the cooling flow per unit area is constant,and the cooling efficiency is the highest in the hole arrangement of p/l=0.0689,s/l=0.1078,at the same time,the location of corrugated center line has little effect on the film cooling efficiency on the wall.Then,based on the optimal parameters,the influence of wave shape and hole inclination angle on the flow and heat transfer characteristics of longitudinal heat shield is discussed.The high temperature zone is mainly concentrated at the peak and the secondary windward side wall temperature is lower than the leeward side with the change of corrugated structure,the cooling efficiency of the air film is gradually increased and fluctuates(except the flat plate)along the flow direction.When the cooling flow rate per unit area is certain,as the inclination angle of the film hole increases,the cooling efficiency of secondary flow of the heat shield increases rapidly on the windward side and decreases slowly on the leeward side,and the highest cooling efficiency occurs at the alternation of peak and valley.Finally,an integrated model of heat shield and casing is constructed to obtain the flow and heat transfer characteristics of different corrugated surface.Under the computational conditions,the cooling efficiency of the full modle transverse corrugated surface increases rapidly at the beginning,then slows down,but it is still in the full development stage of gas film and the efficiency curve basically increases linearly which satisfies the superposition of the gas film.The cooling efficiency of the full modle longitudinal corrugated surface is the lowest at the peak and the highest at the valley. |
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