Study On The Influence Factors Of The Heat Release Law Of Supersonic Combustion In Geometrical Adjustable Combustion Chamber

The scramjet engine has gradually developed into a technical commanding point in the hypersonic advancement field because of its advantages of being able to work in hypersonic conditions and having a high specific impulse.A s one of the most basic technical support,supersonic combustion technology is of great significance to the development of scramjet engines.The heat release law,as the key issue of supersonic combustion,is of extraordinary significance for the development of supersonic combustion,supersonic combustion chambers and even the overall scramjet engine.The law of heat release,that is,the distribution of the total temperature along the combustion chamber,is an important index for evaluating the fuel combustion heat release and the working state of the combustion chamber.It is of great significance for the study of the influence of different influencing factors on the heat release law,which will provide the design of the combustion chamber.Many guiding opinions.In addition,with the continuous development of hypersonic propulsion technology,wide-speed field work has become the latest requirement for scramjet engines,which requires supersonic combustion chambers that can operate under different inflow co nditions,and geometrically adjustable combustion chambers.It is in this context that important products are produced.Therefore,the research on supersonic combustion and heat release in a geometrically adjustable combustion chamber is of great significa nce to the field of hyper-propulsion.For this reason,the research work on the factors affecting the heat release law of the geometrically adjustable combustion chamber is carried out in this paper.The main contents are as follows:Taking the geometrically adjustable combustion chamber as the research object,a two-dimensional numerical simulation of the combustion chamber was carried out,and the effects of the equivalence ratio,expansion ratio,and fuel distribution on the heat release law were studied.Firstly,the research object is geometrically adjustable combustion chamber.This type of combustion chamber is designed to meet the requirements of wide-speed ramjets.It changes the expansion ratio by moving the tip to adapt to various flow conditions.Subsequently,the research program was determined to discuss the influence of the equivalence ratio,expansion ratio,and fuel injection method on the heat release law.The full-scale numerical simulation of different expansion ratios and equivalence rati os for the Ma2-Ma7 inflow conditions was performed on the target combustion chamber.The overall analysis was performed on the influence of several factors on the total temperature cloud map,fuel cloud map,and Mach cloud cloud map.The current heat release law empirical formula and the numerical simulation of the total temperature along the distribution of the distribution,the average temperature along the way through the average cross-sectional mass flow to identify the parameters,analysis along the total temperature rise speed,total temperature rise The relationship between the parameters and the incoming Mach number,the equivalence ratio,and the expansion ratio,conducted an in-depth study of the heat release law,and also found that the increase in the equivalence ratio contributes to the combustion reaction,and the increase in the expansion ratio contributes to the release of heat from combustion.Inhibition and support plate-wall injection methods are beneficial for the combustion reaction of th e support plate injection,and at the same time there is a safety problem of starting without the equivalence ratio being too large.The experiments were carried out on the geometrically adjustable combustor’s ground direct bench.Experiments of different working conditions were performed with different flow conditions,different expansion ratios,different equivalence ratios,and different fuel injection positions as variables,and the total pressure along the pressure curve was calculated.The experiments of different expansion ratios,different equivalence ratios,and different fuel injection positions under conditions of Ma2,Ma4,and Ma6 inflows were performed,and the pressure along the course of the experiment and the back-calculation by a program were obtained.Based on the analysis of Mach number and total temperature data along the way,the influence of various influencing factors on the heat release law was studied.Studies have shown that the increase in the equivalence ratio is beneficial to the combustion heat release,which will push the concentrated heat release to increase the reaction length of the fuel,but it will reduce the instarting of scramjet inlet;the increase of the expansion ratio will cause the combustion to release heat.It acts as a suppressor,but it can increase the instarting of scramjet inlet;the way of expanding the fuel injection in the expansion section not only takes care of the expansion of the safety margin,but also contributes to combustion and heat release.It is a very ideal injection position.An experimental method for predicting the total temperature of the combustion chamber and obtaining the heat release law was developed to verify the accuracy of the method of back-calculating the total temperature through the process pressure.A detachable temperature measurement support plate with a leading edge is designed,and a thermocouple is welded in the front edge of the support plate.The temperature of the inner wall is directly measured and the heat flow of the oute r wall surface is indirectly back-calculated.Then the total temperature of the front edge is calculated by numerical simulation of the heat flow of the outer wall surface of the inner wall.The test was conducted at the outlet of the heater and the engine ’s tail of the engine directly connected to the stage,and the measured temperature was in good agreement with the actual total temperature.This method can be further developed to measure the heat release law by experimental methods.