Cooling Scheme And Experimental Study On Heat Shield Under Combustion Conditions

In this paper,based on the cooling technology of ramjet combustion chamber heat shield,based on the previous research results and engineering design methods,the numerical simulation method is used to study the cooling effect characteristics of the preliminary scheme of the heat shield.The numerical simulation results were compared with the experimental results.At the same time,the heat shield waveform is optimized and the optimization results are applied to the combustion chamber heat shield design.Firstly,numerical simulation and experimental research are carried out for the preliminary scheme of a certain type of ramjet combustion chamber,and the distribution of cold air flow along the path,different cold air inlet temperature,cold air volume ratio,and residual gas wall temperature distribution along the heat shield are obtained.The results show that the wall temperature distribution of the heat shield is high in the first half and the second half in the test results.The distribution of cold air flow along the heat shield has a significant influence on the axial wall temperature distribution and cooling effect.Under the same unit area cold air volume,the use of a smaller heat shield aperture is conducive to the formation of a uniform film cover.The test results under combustion conditions are compared with the numerical simulation results.It turns out that the wall temperature distribution trend is consistent.On the basis of experiments and simulation studies,combined with the axial flow field and the temperature field distribution of the combustion chamber,the layout of single-wave cooling holes and the distribution of cold air flow along the heat shield are adjusted.The numerical simulation results show that the wall temperature along the process is more uniform than the initial scheme,and the wall temperature and maximum wall temperature of the second half of the heat shield are significantly reduced.Finally,the numerical simulation of the cooling characteristics of the asymmetric corrugated heat shield is carried out,and the waveform ratio is optimized.Compared with the symmetric heat shield,the ratio of the windward side to the leeward side flow length is 1:3.The cooling effect is best.Applying this result to the design of the heat shield of a ramjet engine combustor,compared with the symmetrical heat shield,the highest wall temperature of the asymmetric heat shield is reduced by 40 K compared with the symmetrical type,and the wall at the peak of the heat shield The temperature is significantly reduced,the temperature distribution in the rear region of the heat shield is more uniform,and the area of the high temperature region is significantly reduced.