A method for evaluating the compression performance of high-speed inlet

Abstract

The invention belongs to the technical field of aerodynamics of internal flow in a high-speed air intake duct, and discloses a method for evaluating the compression performance of a high-speed air intake duct, the evaluation method comprising: Z1, obtaining inlet parameters and outlet parameters of the air intake duct; Z2, according to the inlet parameters and outlet parameters of step Z1, obtaining the enthalpy change and entropy increase of the airflow from the inlet to the outlet of the air intake duct; Z3, according to the enthalpy change and entropy increase of step Z2, using the enthalpy change divided by the entropy increase, and using the total temperature of the incoming flow for dimensionless processing, to obtain the enthalpy entropy ratio of the air intake duct; Z4, using the enthalpy entropy ratio of the air intake duct to evaluate the compression performance of the high-speed air intake duct; the technology of the invention uses the inlet parameters and outlet parameters of the air intake duct to obtain the enthalpy entropy ratio, and obtains the kinetic energy actually converted by the air intake duct under the condition of unit entropy increase through the enthalpy entropy ratio, which directly reflects the compression degree and compression loss of the airflow by the air intake duct during the compression process, and has obvious significance on the enthalpy entropy diagram, and is suitable for the compression performance evaluation of different types of air intake ducts and the same type of air intake ducts with different parameters.

Description

Technical Field

[0001] The invention relates to the technical field of high-speed air intake internal flow aerodynamics, and in particular to a method for evaluating the compression performance of a high-speed air intake. Background Art

[0002] The high-speed inlet is an important component of the air-breathing engine. Its main function is to capture and compress the incoming flow to provide the engine with a flow rate and flow field that meet the requirements. A high-quality high-speed inlet not only requires the airflow to meet the speed and pressure requirements after compression, but also requires the total pressure loss of the airflow to be as low as possible during the compression process, or the total pressure recovery coefficient of the inlet to be as high as possible. When the compression of the incoming flow by the inlet can achieve the same outlet speed and pressure, the indicator for evaluating the compression performance is the total pressure recovery coefficient of the inlet. However, in most cases, the speed and pressure of the outlet airflow after the inlet compresses the incoming flow only meet a certain range, and it is often encountered that the outlet Mach number and total pressure recovery coefficient are high and the pressure ratio is low. At this time, the total pressure recovery coefficient alone is not enough to evaluate its compression performance, and an indicator that can reflect both the outlet speed and pressure and the total pressure recovery performance must be used.

[0003] The indicators used in the prior art include single indicators and composite indicators. The single indicators include the total pressure recovery coefficient σ and the static pressure ratio π. These indicators cannot simultaneously reflect the compression degree and total pressure loss of the intake duct, and it is impossible to evaluate the compression performance of the high-speed intake duct through a single indicator of the intake duct.

[0004] The composite index mainly includes compression efficiency η B , process efficiency η KD , kinetic efficiency η KE , compression efficiency η 1. Among these composite indicators, compression efficiency η B , process efficiency η KD , Kinetic efficiency η KE Both implicitly express the relationship between the degree of compression and the total pressure loss, and the compression efficiency η 1 implicitly reflects the relationship between enthalpy change and entropy increase, but the significance of these composite indicators in the logarithmic enthalpy-entropy diagram is not obvious, and all these composite indicators cannot intuitively display the compression performance of the intake duct. Summary of the invention

[0005] In order to solve the problems in the background technology, the present invention aims to provide a method for evaluating the compression performance of a high-speed intake duct, by obtaining the enthalpy-entropy ratio of the intake duct through the inlet parameters and outlet parameters of the intake duct, by comprehensively evaluating the degree of compression and the total pressure loss of the airflow by the intake duct through the enthalpy-entropy ratio, and by obtaining the compression performance of the intake duct through a comprehensive evaluation of the degree of compression and the total pressure loss.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for evaluating high-speed intake duct compression performance comprises the following steps:

[0008] Get the inlet and outlet parameters of the inlet duct. The inlet parameters include: the incoming flow Mach number Yes 0. Incoming static pressure P 0. Incoming flow static temperature T 0, export parameters include: export Mach number Yes e , outlet static pressure P e , outlet static temperature T e ;

[0009] According to the inlet parameters and the outlet parameters, the enthalpy change and entropy increase of the airflow from the inlet to the outlet are obtained, including steps Z21-Z22:

[0010] According to the static temperature of the incoming flow in the inlet parameters T 0 and outlet static temperature T e , the enthalpy change of the airflow from the inlet to the outlet is calculated according to the following formula △ h :

[0011]

[0012] in h 0 is the enthalpy of the airflow at the inlet, h e is the enthalpy of the airflow at the inlet duct outlet, △ h is the enthalpy change of the airflow from the inlet to the outlet, that is, the kinetic energy actually converted by the inlet. C P is the specific heat capacity at constant pressure, R is the gas constant and for air R=287J / (Kg·K), γ is the specific heat ratio and to air γ =1.4;

[0013] According to the inlet parameters and the outlet parameters, the entropy increase △S of the airflow from the inlet to the outlet of the air inlet is obtained, which includes the following steps:

[0014] Incoming flow Mach number according to inlet parameters Yes 0. Incoming static pressure P 0. Incoming flow static temperature T 0, calculate the total inflow pressure according to the following formula P 0 * Total temperature of incoming flow T 0 * :

[0015]

[0016] in γ is the specific heat ratio and to air γ =1.4;

[0017] Exit Mach number according to exit parameters Yes e , outlet static pressure P e , outlet static temperature T e , calculate the total outlet pressure according to the following formula P e * and outlet total temperature T e * :

[0018]

[0019] in γ is the specific heat ratio and to air γ =1.4;

[0020] According to the calculated total inflow pressure P 0 * , total temperature of incoming flow T 0 * , total outlet pressure P e * and outlet total temperature T e * , the entropy increase △S of the airflow from the inlet to the outlet is obtained according to the following formula:

[0021]

[0022] Where S0 is the entropy of the airflow at the inlet, S e is the entropy of the airflow at the inlet outlet, C P is the constant pressure specific heat capacity described in step Z21, R is the gas constant and for air R=287J / (Kg·K), and Ln is a logarithmic function;

[0023] The enthalpy change △ h and entropy increase △S as the quotient, and use the total temperature of the incoming flow T 0 * After dimensionless processing, the enthalpy-entropy ratio of the intake duct is obtained according to the following formula: X , h That is, the incoming kinetic energy actually converted by the intake duct under the condition of unit entropy increase:

[0024]

[0025] Where R is the gas constant and for air R=287J / (Kg·K), C P is the specific heat capacity at constant pressure, T 0 is the static temperature of the incoming flow, T e is the outlet static temperature, T 0 * It is to flow the total temperature, P 0 * is the total inflow pressure, P e * is the total outlet pressure;

[0026] According to the obtained enthalpy-entropy ratio of the intake duct X , h Get the compression performance of a high-speed intake:

[0027] Considering the adiabatic process of the inlet duct, T e * = T 0 * In the case of X , h The following formula is used for conversion, and the conventional pressure ratio, total pressure recovery coefficient and incoming flow Mach number are used to comprehensively evaluate the aerodynamic performance of the inlet:

[0028]

[0029] in, γ is the specific heat ratio and to air γ =1.4, C P is the specific heat capacity at constant pressure, R is the gas constant and for air R=287J / (Kg·K), Yes 0 is the incoming flow Mach number, π is the pressure ratio and π= P e / P 0, σ is the total pressure recovery coefficient and σ= P e * / P 0 * , T 0 is the static temperature of the incoming flow, T e is the outlet static temperature, T 0 * It is to flow the total temperature, T e * is the total outlet temperature, P 0 is the static pressure of the incoming flow,P e is the outlet static pressure, P 0 * is the total inflow pressure, P e * is the total outlet pressure;

[0030] Given the incoming flow Mach number Yes e , the enthalpy-entropy ratio of the intake duct X , h It is a function of the pressure ratio π and the total pressure recovery coefficient σ. The pressure ratio π reflects the degree of compression of the airflow by the inlet duct. The total pressure recovery coefficient σ reflects the total pressure loss of the inlet duct during the compression process. The enthalpy entropy ratio of the inlet duct X , h It can be used to comprehensively evaluate the compression degree and compression loss of the intake duct; enthalpy entropy ratio X , h The larger it is, the higher the kinetic energy actually converted into the intake duct under the same entropy increase conditions, and the better the compression performance.

[0031] Furthermore, the enthalpy-entropy ratio of the intake duct X , h The meaning is obvious on the enthalpy-entropy diagram, which represents the slope of the line connecting the intake duct entrance point 0 and the intake duct exit point e; where point 0 is the entrance of the intake duct and point e is the exit of the intake duct.

[0032] Furthermore, the adiabatic process of the intake duct is considered in the calculation of the entropy increase △S, that is, T e * = T 0 * In the case of, the calculation formula of entropy increase △S between the inlet and outlet of the intake duct is simplified to:

[0033]

[0034] Where R is the gas constant and for air R=287J / (Kg·K), P e * is the total outlet pressure, P 0 * is the total incoming flow pressure.

[0035] Furthermore, in calculating the enthalpy-entropy ratio X , h In the process, the adiabatic process of the inlet duct is considered, that is, T e * = T 0 * In the case of X , hThe calculation formula is simplified to:

[0036]

[0037] Where R is the gas constant and for air R=287J / (Kg·K), C P is the constant pressure specific heat capacity described in step Z21, T 0 is the static temperature of the incoming flow, T e is the outlet static temperature, T 0 * It is to flow the total temperature, P 0 * is the total inflow pressure, P e * is the total outlet pressure.

[0038] Beneficial effects of the technical solution: 1. The technical method of the present invention can replace multiple single indicators to evaluate the compression performance of the intake duct; 2. The enthalpy entropy ratio obtained by the evaluation method of the present invention X , h The expression in the enthalpy-entropy diagram is intuitive and meaningful, and it represents the slope of the line connecting the inlet duct entrance point 0 and the inlet duct exit point e; 3. The evaluation method of the present invention can evaluate and compare the compression performance of the same type of inlet ducts with different design parameters, and can also evaluate and compare the compression performance of different types of inlet ducts, and its applicability is relatively strong. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A flow chart of a method for evaluating high-speed intake duct compression performance according to the present invention;

[0040] Figure 2 The enthalpy entropy diagram of the intake duct compression process provided by the embodiment of the present invention, wherein point 0 is the inlet of the intake duct, point e is the outlet of the intake duct, S0 is the entropy at the inlet of the intake duct, S e is the entropy at the inlet port outlet, h0 is the enthalpy at the inlet port inlet, and h e is the enthalpy at the inlet duct outlet. The curve where P0 is located is the isobaric line with pressure equal to P0, that is, the inlet inlet isobaric line. e The curve where the pressure is equal to P e The isobaric line is the outlet isobaric line of the inlet duct. P 0 * The curve where is located is the stagnation isobaric line at the inlet entrance. P e * The curve where is located is the stagnation isobaric line at the inlet outlet. P 0 * is the total inlet pressure, P e *is the total outlet pressure, P 0 is the inlet static pressure, P e is the outlet static pressure, i is the intersection point with the inlet inlet isentropic and the inlet outlet isobaric, i.e., the state point when the inlet inlet isentropically compressed to a pressure equal to the outlet static pressure, e,s is the state point when the inlet outlet is isentropically expanded to a pressure equal to the inlet inlet, 0 * is the inlet entrance stagnation point, e* is the inlet exit stagnation point, h0 * is the stagnation enthalpy at the inlet, h e * is the stagnation enthalpy at the inlet port outlet, the horizontal axis S is entropy, and the vertical axis h is enthalpy;

[0041] Figure 3 The logarithmic enthalpy entropy diagram of the intake duct compression process provided by the similar technical description of the present invention; wherein point 0 is the inlet of the intake duct, point e is the outlet of the intake duct, the straight line where P0 is located is the isobaric line with a pressure equal to P0, that is, the inlet isobaric line of the intake duct, P e The straight line where the pressure is equal to P e The isobaric line is the outlet isobaric line of the inlet duct, e,s is the state point where the outlet of the inlet duct expands isentropically to a pressure equal to that of the inlet duct inlet, the ordinate Lnh is the logarithmic enthalpy, the abscissa S is the entropy, Δ1=Lnh e -Lnh e,s , Δ2=Lnh e -Lnh0. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments:

[0043] like Figure 1 As shown, a method for evaluating the compression performance of a high-speed intake duct comprises the following steps:

[0044] Z1. Obtain the inlet and outlet parameters of the inlet duct. The inlet parameters include: the incoming flow Mach number Yes 0. Incoming static pressure P 0. Incoming flow static temperature T 0, export parameters include: export Mach number Yes e , outlet static pressure P e , outlet static temperature T e ;

[0045] Z2, according to the inlet parameters and outlet parameters of step Z1, the enthalpy change and entropy increase of the airflow from the inlet to the outlet of the air inlet are obtained, including steps Z21-Z22:

[0046] Z21, according to the static temperature of the incoming flow in step Z1T 0 and outlet static temperature T e , the enthalpy change of the airflow from the inlet to the outlet is calculated according to the following formula △ h :

[0047]

[0048] in h 0 is the enthalpy of the airflow at the inlet, h e is the enthalpy of the airflow at the inlet duct outlet, △ h is the enthalpy change of the airflow from the inlet to the outlet, that is, the kinetic energy actually converted by the inlet. C P is the specific heat capacity at constant pressure, R is the gas constant and for air R=287J / (Kg·K), γ is the specific heat ratio and to air γ =1.4;

[0049] Z22, according to the inlet parameters and outlet parameters of step Z1, obtaining the entropy increase ΔS of the airflow from the inlet to the outlet of the air inlet, comprising the following steps:

[0050] Z2201, according to the incoming flow Mach number of step Z1 Yes 0. Incoming static pressure P 0. Incoming flow static temperature T 0, calculate the total inflow pressure according to the following formula P 0 * Total temperature of incoming flow T 0 * :

[0051]

[0052] in γ is the specific heat ratio and to air γ =1.4;

[0053] Z2202, according to the exit Mach number of step Z1 Yes e , outlet static pressure P e , outlet static temperature T e , calculate the total outlet pressure according to the following formula P e * and outlet total temperature T e * :

[0054]

[0055] in γ is the specific heat ratio and to air γ =1.4;

[0056] Z2203, according to the total pressure of the incoming flow in step Z2201 P 0 * Total temperature of incoming flow T 0 * , the outlet total pressure in step Z2202 P e * and outlet total temperature T e * , the entropy increase △S of the airflow from the inlet to the outlet is obtained according to the following formula:

[0057]

[0058] Considering the adiabatic process of the inlet duct, T e * = T 0 * In the case of, the calculation formula of entropy increase △S between the inlet and outlet of the intake duct is simplified to:

[0059]

[0060] Where S0 is the entropy of the airflow at the inlet, S e is the entropy of the airflow at the inlet outlet, C P is the constant pressure specific heat capacity described in step Z21, R is the gas constant and for air R=287J / (Kg·K), P e * is the total outlet pressure, P 0 * is the total incoming flow pressure;

[0061] Z3, the enthalpy change obtained in step Z2 h and entropy increase △S as the quotient, and use the total temperature of the incoming flow T 0 * After dimensionless processing, the enthalpy-entropy ratio of the intake duct is obtained according to the following formula: X , h That is, the incoming kinetic energy actually converted by the intake duct under the condition of unit entropy increase:

[0062]

[0063] Considering the adiabatic process of the inlet duct, T e * = T 0 *In the case of X , h The calculation formula is simplified to:

[0064]

[0065] Where R is the gas constant and for air R=287J / (Kg·K), C P is the constant pressure specific heat capacity described in step Z21, T 0 is the static temperature of the incoming flow, T e is the outlet static temperature, T 0 * It is to flow the total temperature, P 0 * is the total inflow pressure, P e * is the total outlet pressure.

[0066] Z4. Obtain the compression performance of the high-speed intake duct based on the intake duct enthalpy-entropy ratio:

[0067] Z41, consider the adiabatic process of the intake duct, that is, T e * = T 0 * In the case of X , h The following formula is used for conversion, and the conventional pressure ratio, total pressure recovery coefficient and incoming flow Mach number are used to comprehensively evaluate the aerodynamic performance of the inlet:

[0068]

[0069] in, γ is the specific heat ratio and to air γ =1.4, C P is the constant pressure specific heat capacity described in step Z21, R is the gas constant and for air R=287J / (Kg·K), Yes 0 is the incoming flow Mach number, π is the pressure ratio and π= P e / P 0, σ is the total pressure recovery coefficient and σ= P e * / P 0 * , T 0 is the static temperature of the incoming flow, T e is the outlet static temperature, T 0 * It is to flow the total temperature, Te * is the total outlet temperature, P 0 is the static pressure of the incoming flow, P e is the outlet static pressure, P 0 * is the total inflow pressure, P e * is the total outlet pressure;

[0070] Z42, given incoming flow Mach number Yes e , the enthalpy-entropy ratio of the intake duct X , h It is a function of the pressure ratio π and the total pressure recovery coefficient σ. The pressure ratio π reflects the degree of compression of the airflow by the inlet duct. The total pressure recovery coefficient σ reflects the total pressure loss of the inlet duct during the compression process. The enthalpy entropy ratio of the inlet duct X , h It can be used to comprehensively evaluate the compression degree and compression loss of the intake duct; enthalpy entropy ratio X , h The larger it is, the higher the kinetic energy actually converted into the intake duct under the same entropy increase conditions, and the better the compression performance.

[0071] like Figure 2 As shown, this is the enthalpy-entropy diagram of the intake compression process. The enthalpy-entropy ratio of the intake X , h Its meaning is obvious on the enthalpy-entropy diagram, representing the slope of the line connecting the inlet entry point 0 and the inlet exit point e.

[0072] The difference between the present invention and the existing similar technologies

[0073] The prior art similar to the technical solution of the present invention includes the comparative document "Parameters for eva-luating the efficiency of inlet compression" (English version). The difference between the present invention and the technical solution in the comparative document is now explained.

[0074] The differences between the present invention and the technical solutions of the reference documents include the following three aspects:

[0075] 1. Different ways to obtain technical indicators

[0076] The technical solution of the present invention directly obtains the enthalpy change △h and entropy increase △S of the airflow from the inlet to the outlet of the inlet according to the inlet parameters and outlet parameters of the inlet, and directly obtains the enthalpy entropy ratio of the inlet by dividing the enthalpy change △h by the entropy increase △S. X , h ;

[0077] The comparison document obtains the compression efficiency η1 with an assumption and a process: one assumption is to decompose the compression process of the intake duct into a series of sub-compression processes, assuming that the compression efficiency η1 is equal to the compression efficiency η of each sub-compression process 1i , where i is the serial number of the i-th sub-compression process, i=1,2,3,…,N, N is a positive integer. This assumption is mathematically reasonable, but it still needs to be evaluated and confirmed in the physical sense; one treatment is to take the logarithm of the enthalpy h to obtain the logarithmic enthalpy Ln h, so the isobars in the logarithmic enthalpy-entropy diagram change from curves to straight lines.

[0078] 2. Different definitions of technical indicators

[0079] In the technical solution of the present invention, Figure 2 In the enthalpy-entropy diagram of the intake compression process shown in the figure, the enthalpy-entropy ratio of the intake duct is obtained by dividing △h by △S. X , h ;

[0080] In the comparative documents, Figure 3 As shown in the logarithmic enthalpy entropy diagram, the difference in logarithmic enthalpy Δ1=Lnh e -Lnh e,s Divided by the difference in logarithmic enthalpy Δ2 = Lnh e - Lnh 0 Get the compression efficiency η1 of the intake duct.

[0081] 3. The intuitive meaning of technical indicators in enthalpy-entropy diagrams is different

[0082] In the technical solution of the present invention, Figure 2 In the enthalpy-entropy diagram of the intake duct compression process shown in the figure, the slope of the line connecting the intake duct inlet point 0 and the intake duct outlet point e represents the enthalpy-entropy ratio of the intake duct. X , h , the greater the slope, the greater the enthalpy entropy ratio of the intake duct X , h The larger the value, the better the compression performance of the high-speed inlet duct, the smaller the slope, and the enthalpy-entropy ratio of the inlet duct. X , h The smaller it is, the worse the compression performance of the high-speed intake duct is, and the enthalpy-entropy ratio X , h The meaning on the enthalpy-entropy diagram is very intuitive;

[0083] In the comparison documents, Figure 3 As shown, since the compression efficiency η1 of the intake duct is the ratio of Δ1 to Δ2, on the logarithmic enthalpy entropy diagram, assuming that point e moves up along the isentropic line, that is, the total pressure recovery coefficient σ of the compression process 0-e remains unchanged, but the pressure ratio π increases, Δ1=Lnh e -Lnh e,sWith Δ2= Lnh e - Lnh 0 If both increase, it is not intuitive to judge the compression efficiency η1 of the intake duct on the logarithmic enthalpy entropy diagram; assuming that point e moves to the left along the isobaric line, that is, the pressure ratio π remains unchanged and the entropy s decreases, Lnh e , Lnh e,s , Δ1=Lnh e -Lnh e,s , Δ2= Lnh e - Lnh 0 If both decrease, it will be even less intuitive to judge the compression efficiency η1 of the intake duct on the logarithmic enthalpy-entropy diagram.

[0084] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the technical solution of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for evaluating the compression performance of a high-speed intake duct, characterized in that , including the following steps: Z1, obtain the inlet and outlet parameters of the air inlet; Z2. According to the inlet parameters and outlet parameters of step Z1, the enthalpy change △h and entropy increase △S of the airflow from the inlet to the outlet of the air inlet are obtained; Z3, taking the enthalpy change △h and entropy increase △S obtained in step Z2 as the quotient, and using the total temperature of the incoming flow for dimensionless processing, to obtain the enthalpy-entropy ratio Ks,h of the inlet duct; Z4, evaluating the compression performance of the high-speed intake duct according to the intake duct enthalpy entropy ratio Ks,h obtained in step Z3; In step Z2, the calculation process of enthalpy change Δh is as follows: according to the static temperature of the incoming flow T0 in the inlet parameters and the static temperature of the outlet T in the outlet parameters e , calculate the enthalpy change △h of the airflow from the inlet to the outlet according to the following formula: Δh=h e -h0=C P (T e -T0) Where h0 is the enthalpy of the airflow at the inlet, h e is the enthalpy of the airflow at the inlet duct outlet, △h is the enthalpy change of the airflow from the inlet duct inlet to the outlet, that is, the kinetic energy actually converted by the inlet duct, C P is the specific heat capacity at constant pressure, R is the gas constant and for air R = 287 J / (Kg·K), γ is the specific heat ratio and for air γ = 1.4; In step Z2, the calculation process of the entropy increase ΔS is: according to the inlet parameters of the incoming flow Mach number Ma0, the incoming flow static pressure P0, and the incoming flow static temperature T0, the incoming flow total pressure P0 is calculated according to the following formula: * Total temperature of incoming flow T0 * : where γ is the specific heat ratio and for air γ = 1.4; According to the exit Mach number Ma in the inlet parameters e , outlet static pressure P e and outlet static temperature T e , calculate the total outlet pressure P according to the following formula e * and outlet total temperature T e *: where γ is the specific heat ratio and for air γ = 1.4; According to the obtained total inflow pressure P0*, total inflow temperature T0*, and total outlet pressure P e * and outlet total temperature T e *, the entropy increase △S between the airflow from the inlet to the outlet is calculated according to the following formula: Where S0 is the entropy of the airflow at the inlet, S e is the entropy of the airflow at the inlet outlet, C P is the specific heat capacity at constant pressure, R is the gas constant and for air R = 287 J / (Kg·K); In step Z3, the enthalpy-entropy ratio Ks,h of the intake duct, i.e., the incoming kinetic energy actually converted by the intake duct under the condition of unit entropy increase, is calculated according to the following formula: Where R is the gas constant and for air R = 287 J / (Kg·K), C P is the specific heat capacity at constant pressure, T0 is the static temperature of the incoming flow, T e is the outlet static temperature, T0 * is the total temperature of the incoming flow, P0 * is the total incoming pressure, P e * is the total outlet pressure; In step Z4, when evaluating the compression performance of the high-speed intake duct using the enthalpy-entropy ratio Ks,h, the intake duct adiabatic process, i.e., T e * =T0 * In the case of , the enthalpy-entropy ratio Ks,h of the inlet is converted according to the following formula, and the conventional pressure ratio, total pressure recovery coefficient and incoming flow Mach number are used to comprehensively evaluate the aerodynamic performance of the inlet: Where γ is the specific heat ratio and for air γ = 1.4, C P is the specific heat capacity at constant pressure, R is the gas constant and for air R = 287 J / (Kg·K), Ma0 is the incoming flow Mach number, π is the pressure ratio and π = P e / P0, σ is the total pressure recovery coefficient and σ=P e * / P0 * , T0 is the static temperature of the incoming flow, T e is the outlet static temperature, T0 * is the total temperature of the incoming flow, T e * is the total outlet temperature, P0 is the static pressure of the incoming flow, P e is the outlet static pressure, P0 * is the total incoming pressure, P e * is the total outlet pressure; In this formula, the incoming flow Mach number Ma is given e The enthalpy-entropy ratio Ks,h of the inlet duct is a function of the pressure ratio π and the total pressure recovery coefficient σ.

2. A method for evaluating high-speed intake duct compression performance according to claim 1, characterized in that: The inlet parameters in step Z1 include: the incoming flow Mach number Ma0, the incoming flow static pressure P0 and the incoming flow static temperature T0, and the outlet parameters include: the outlet Mach number Ma e , outlet static pressure P e and outlet static temperature T e .

3. A method for evaluating high-speed intake duct compression performance according to claim 1, characterized in that: In step Z4, the enthalpy-entropy ratio Ks,h of the intake duct is obvious on the enthalpy-entropy diagram, which represents the slope of the line connecting the intake duct inlet point 0 and the intake duct outlet point e; Point 0 is the entrance of the air intake duct, and point e is the exit of the air intake duct.

4. The method for evaluating high-speed intake duct compression performance according to claim 1, characterized in that: In the process of calculating the entropy increase △S, the adiabatic process of the intake duct is considered, that is, T e * =T0 * In the case of, the calculation formula of entropy increase △S between the inlet and outlet of the intake duct is simplified to: Where R is the gas constant and for air R = 287 J / (Kg·K), P e * is the total outlet pressure, P0 * is the total incoming flow pressure.

5. The method for evaluating high-speed intake duct compression performance according to claim 1, characterized in that: In the process of calculating the intake enthalpy entropy ratio Ks,h, the intake adiabatic process, i.e., T e * =T0 * In this case, the calculation formula is simplified to: Wherein R is the gas constant and for air R = 287 J / (Kg·K), CP is the constant-pressure specific heat capacity described in step Z21, T0 is the static temperature of the incoming flow, Te is the static temperature of the outlet, T0* is the total temperature of the incoming flow, P0* is the total pressure of the incoming flow, and Pe* is the total pressure of the outlet.

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