CN-121980831-A - Progressive and exhaust matching design method for scramjet engine

CN121980831ACN 121980831 ACN121980831 ACN 121980831ACN-121980831-A

Abstract

The application belongs to the field of engine emission matching design, and particularly relates to an emission matching design method of a scramjet engine. The method comprises the steps of obtaining parameters of an air inlet passage for the initially designed air inlet passage, checking whether the flow of the air inlet passage meets the use requirement of an engine, determining working condition points which do not meet the requirement, carrying out deviation pulling on the total pressure recovery coefficient and the flow coefficient of the air inlet passage corresponding to the working condition points, giving out characteristic line slopes of each additional working condition, forming a plurality of calculation points in the range of the characteristic line slopes which can be designed for the air inlet passage, determining an air inlet passage flow coefficient calculation value of each calculation point under the deviation pulling value of the total pressure recovery coefficient of each air inlet passage, interpolating corresponding engine performance data in the additional working condition, thereby constructing a functional relation between the engine performance data and the deviation pulling value of the total pressure recovery coefficient of the air inlet passage, and carrying out redesign on an air inlet passage scheme according to thrust requirement. The application can realize the matching optimization of the concurrency and the discharge of the ramjet and improve the service performance of the ramjet.

Inventors

ZHANG CHENLIN
LIANG XINGZHUANG
HUANG LEI
ZHU WEI
HUA ZHENGXU

Assignees

中国航空工业集团公司沈阳飞机设计研究所

Dates

Publication Date: 20260505
Application Date: 20260408

Claims (5)

1. The method for matching and designing the progressive emission of the scramjet engine is characterized by comprising the following steps of: S1, acquiring inlet channel parameters of an initially designed inlet channel, wherein the inlet channel parameters at least comprise height, mach number, attack angle, inlet channel flow coefficient, inlet channel total pressure recovery coefficient, inlet channel supercharging ratio, inlet channel speed distortion and thrust coefficient; S2, inputting parameters of an air inlet channel into an engine performance database, and checking whether the flow of the air inlet channel under the maximum throat area and the minimum residual air coefficient meets the use requirement of the engine or not, if the flow of the air inlet channel does not meet the requirement, determining working points which do not meet the requirement, wherein the working points consist of height, mach number and attack angle; S3, for each working point which does not meet the requirement, carrying out deviation pulling on the total pressure recovery coefficient of the air inlet channel corresponding to the working point to obtain a plurality of total pressure recovery coefficient deviation values of the air inlet channel, simultaneously, carrying out deviation pulling on the flow coefficient of the air inlet channel of the working point to obtain a plurality of flow coefficient deviation values of the air inlet channel, combining the total pressure recovery coefficient deviation values of the air inlet channel and the flow coefficient deviation values of the air inlet channel to form additional working conditions, and giving out characteristic line slope and engine performance data of each additional working condition, wherein the characteristic line slope refers to the ratio of the total pressure recovery coefficient deviation value of the air inlet channel to the flow coefficient deviation value of the air inlet channel, and the engine performance data comprises engine thrust and engine throat diameter; S4, forming a plurality of calculation points in the slope range of the characteristic line which can be designed for the air inlet, and determining the calculated value of the flow coefficient of the air inlet under the deviation value of the total pressure recovery coefficient of each air inlet at each calculation point; S5, interpolating engine performance data corresponding to the calculated value of the flow coefficient of each air inlet channel for each air inlet channel total pressure recovery coefficient, so as to construct a functional relation between the engine performance data and the air inlet channel total pressure recovery coefficient; And S6, redesigning the scheme of the air inlet channel according to the thrust requirement and according to the functional relation, and returning to the step S1 for iterative calculation based on the newly designed air inlet channel.
2. The method for matching and designing the emission of the scramjet engine according to claim 1, wherein in the step S1, the flow coefficient of the air inlet is the ratio of the outlet mass flow of the air inlet to the capture mass flow of the reference area of the air inlet, the total pressure recovery coefficient of the air inlet is the ratio of the outlet total pressure of the air inlet to the total incoming flow pressure of a far field, the supercharging ratio of the air inlet is the ratio of the outlet static pressure of the air inlet to the incoming static pressure of the far field, the speed distortion of the air inlet is the ratio of the difference between the maximum speed and the minimum speed of the outlet of the air inlet to the average speed of the outlet, and the thrust coefficient is the ratio of the actual thrust of the jet pipe to the ideal thrust.
3. The method for matching the incidence of a ramjet engine according to claim 2, wherein said desired thrust force Calculated by the following formula: ; Wherein, the Is the air inlet flow rate of the spray pipe, Is the specific heat ratio of the gas, Is a gas constant which is a general purpose gas constant, The total temperature of the inlet of the spray pipe is, The actual thrust of the spray pipe is the sum of the thrust of the stagnation inlet of the spray pipe and the integral of the axial pressure of the wall surface of the spray pipe.
4. The method for matching and designing the secondary combustion ramjet engine firing line according to claim 1, wherein in step S3, when the total pressure recovery coefficient of the intake duct and the flow coefficient of the intake duct are biased, the amount of bias is within plus or minus 10% of the reference value.
5. The method for matching and designing the secondary combustion ramjet engine firing schedule according to claim 1, wherein the functional relationship between the engine performance data and the total pressure recovery coefficient of the intake duct is a quadratic function.

Description

Progressive and exhaust matching design method for scramjet engine Technical Field The application belongs to the field of engine emission matching design, and particularly relates to an emission matching design method of a scramjet engine. Background The sub-combustion ramjet engine is used as an air suction type high-speed power device, has higher thrust and specific impulse compared with power forms such as a turbine engine and the like under the flight speed range with the Mach number M of 2-4, has a simple structure and no rotating part, and is an ideal power selection of a cruise aircraft under the speed range. The sub-combustion ramjet engine consists of an air inlet channel, a combustion chamber and a tail jet pipe, wherein the air inlet channel is mainly used for decelerating and pressurizing incoming air to achieve the air flow condition required by the operation of the combustion chamber, the combustion chamber is used for mixing and burning incoming air entering the air inlet channel and fuel carried by the engine to realize the conversion of chemical energy of the fuel into heat energy and heating the incoming air, and the jet pipe is used for reducing and accelerating high-enthalpy air flow in the combustion chamber to realize the conversion from heat energy to kinetic energy so as to generate thrust and push an aircraft to advance. The traditional sub-combustion ramjet engine generally adopts an integrated design of an air inlet channel, a combustion chamber and a tail nozzle, namely an integrated design of an emission row, is uniformly completed by a power unit, has a relatively fixed working point, has no geometric adjustment mechanism in the emission row, has a fixed geometric profile of an inner flow channel, has few design variables, has a single design target and lower performance requirement, and is relatively large in emission row matching margin and relatively direct in design. However, for wide-speed-range scramjet engines for aircraft, the design faces distinct challenges. Firstly, due to the requirement of integration of the aircraft, the aerodynamic and structural design of the exhaust system of the air intake duct is generally assumed by the aircraft overall units, while the combustion chamber is assumed by the power units, which results in the design process involving data interactions and iterations between the units. Secondly, in order to meet performance requirements of different flight states (such as climbing and cruising) in a wide speed range, an air inlet channel and a spray pipe of the engine are often provided with a geometric adjustment mechanism (such as an adjustable throat), so that a complex coupling relation and a large matching degree of freedom exist among air inlet flow, combustion chamber inlet conditions and engine residual air coefficients. Therefore, in the design of the aircraft wide-speed-range sub-combustion ramjet engine, under the constraint that the air inlet, the air outlet and the combustion chamber are designed by different units and are required to be optimized at a plurality of working points, a set of system and efficient matching flow and method are established to cooperatively determine key parameters, and finally, the optimal performance of the engine in the wide speed range, particularly at non-design points, becomes a technical problem to be solved. Disclosure of Invention In order to solve the problems, the application provides a sub-combustion ramjet engine emission matching design method, which is oriented to the flying integrated design process of a large-size sub-combustion ramjet engine by the general unit of the aviation field, and forms an emission matching flow and method under different constraint conditions in a wide speed domain by the sub-combustion ramjet engine emission integrated matching requirement, thereby providing means for optimizing the thrust performance of a wide speed domain aircraft. The application provides a method for matching and designing the progressive emission of a scramjet engine, which mainly comprises the following steps: S1, acquiring inlet channel parameters of an initially designed inlet channel, wherein the inlet channel parameters at least comprise height, mach number, attack angle, inlet channel flow coefficient, inlet channel total pressure recovery coefficient, inlet channel supercharging ratio, inlet channel speed distortion and thrust coefficient; S2, inputting parameters of an air inlet channel into an engine performance database, and checking whether the flow of the air inlet channel under the maximum throat area and the minimum residual air coefficient meets the use requirement of the engine or not, if the flow of the air inlet channel does not meet the requirement, determining working points which do not meet the requirement, wherein the working points consist of height, mach number and attack angle; S3, for each working point which does not meet the requirement, carrying out deviation p