CN115203975A - Method for evaluating performance attenuation of military aviation turbofan engine in installed state - Google Patents

Abstract

The present application belongs to the technical field of engine design, and in particular relates to a method for evaluating the performance degradation of a military aviation turbofan engine in an installed state. The method includes step S1: during the take-off period of the aircraft, the engine working state is the maximum state and the ground speed is within a set range, and the aircraft flight parameters at each moment are obtained; step S2, the take-off thrust of a single engine at each moment is determined based on the aircraft flight parameters. F; Step S3, the single engine take-off thrust F is uniformly corrected to the combat state thrust F _combat ; Step S4, the combat state thrust F _combat is corrected to the thrust F _P under the sea level height; Step S5, by the sea level height The thrust F _P is corrected to the sea level standard temperature thrust F _T ; Step S6, establishes the relation curve of the sea level standard temperature thrust F _T with flight sorties or flight time, and forms the engine thrust performance attenuation variation trend. This application can effectively guide the user to quickly and directly grasp the engine performance level.

Description

A method for evaluating the performance degradation of military aviation turbofan engine in installed state

technical field

The application belongs to the technical field of engine design, and in particular relates to a method for evaluating the performance attenuation of a military aviation turbofan engine in an installed state.

Background technique

With the advantages of high stability margin and large cruising range, turbofan engines have gradually developed into the preferred power plant for military engines. After the engine is officially put into service, there is objectively a certain degree of performance degradation during the entire life cycle. The direct manifestation of the performance degradation is the decrease in the thrust level of the engine, which will have a certain impact on the use of the aircraft:

1. The engine has the problem of thrust reduction in typical harsh environments such as high temperature days and plateaus. The performance of the engine with serious performance degradation will be more obvious, which increases the take-off roll distance of the aircraft and seriously threatens the take-off safety of the aircraft;

2. When two engines with large differences in performance attenuation are installed on the same aircraft, it is easy to affect the aircraft trim and cause the aircraft to roll and yaw.

Therefore, it is very necessary to evaluate the performance degradation level of the engine in the installed state. However, due to the lack of direct measurement of thrust in the installed environment, it is impossible to objectively and directly evaluate the performance degradation.

At present, the performance attenuation evaluation method commonly used in China is to correct the actual exhaust temperature of the engine to the same speed level of the standard atmosphere at sea level, indirectly evaluate the performance attenuation through the increase in exhaust temperature, and use the increase in exhaust temperature to indirectly evaluate The method of engine performance attenuation level has the following disadvantages:

1. The evaluation method is not intuitive. The traditional performance attenuation evaluation method evaluates the change of the exhaust temperature level, but for the aircraft or users, the intuitive performance of the performance attenuation is the reduction of the thrust level, and the relationship between the exhaust temperature and the thrust level cannot be quickly and accurately determined. For conversion, the original evaluation method lacks operability in the actual use process.

2. There is no clear correspondence between exhaust temperature and thrust. The exhaust temperature after the turbine can characterize the internal exhaust speed to a certain extent, but for a turbofan engine, another important factor for thrust is the air flow. If there are changes, there is a certain intake distortion in the installed state, and the correlation between the exhaust temperature and the thrust cannot be accurately established.

SUMMARY OF THE INVENTION

In order to solve one of the above problems, the present application provides a method for evaluating the performance degradation of a military aviation turbofan engine in an installed state, which can accurately characterize the variation law of the engine thrust level with the use time, and solve the unintuitiveness of the original performance degradation evaluation method. and other issues to improve the operability of thrust evaluation under installed conditions.

The present application provides a method for evaluating the performance degradation of a military aviation turbofan engine in an installed state, which mainly includes:

Step S1, during the take-off period of the aircraft, the engine working state is the maximum state, and the ground speed is within the set range, and the aircraft flight parameters at each moment are obtained;

Step S2, determining the take-off thrust F of a single engine at each moment based on the aircraft flight parameters;

Step S3, uniformly correct the take-off thrust F of a single engine to the combat state thrust F _combat , and determine the low-pressure physical speed of the engine n _L-combat in the corresponding combat state, and the engine exhaust temperature T _6-combat ;

Step S4, the _combat state thrust F is corrected to the thrust F _P under the height of the sea level;

Step S5, the low-pressure physical rotation speed of the engine under the combat state n _L-combat , and the engine exhaust temperature T6 _-combat determine a thrust correction coefficient, and based on the thrust correction coefficient, correct the thrust F _P at sea level to sea level Standard temperature thrust F _T ;

Step S6, establishing a relationship curve of sea level standard temperature thrust F _T with flight sorties or flight time, forming a change trend of engine thrust performance attenuation, and the engine thrust performance attenuation change trend is used to characterize the degree of performance attenuation of the aviation turbofan engine.

Preferably, in step S1, the setting range of the ground speed is 140 km/h to 160 km/h.

Preferably, in step S2, calculating the take-off thrust of a single engine includes:

Calculate the total engine thrust;

Determined according to the number of engines, the take-off thrust of a single engine.

Preferably, calculating the total engine thrust _Fw includes:

为发动机推力角。Among them, m ₀ is the weight of the take-off configuration of the aircraft, m _fuel is the fuel quantity of the aircraft, a _x is the longitudinal acceleration of the aircraft, F _resistance is the sum of the aerodynamic resistance and frictional resistance generated during the take-off process of the aircraft, α is the angle of attack of the aircraft,

is the engine thrust angle.

Preferably, calculating the total engine thrust includes:

为发动机推力角。Among them, m ₀ is the weight of the take-off configuration of the aircraft, m _fuel is the fuel quantity of the aircraft, V is the ground speed of the aircraft, F _resistance is the sum of the aerodynamic resistance and frictional resistance generated during the take-off process of the aircraft, α is the angle of attack of the aircraft,

is the engine thrust angle.

Preferably, in step S3, calculating the combat state thrust F _combat includes:

If in step S1, the state of the aircraft in the take-off stage is the take-off in the combat state, then the calculated take-off thrust F of the single engine is the combat state thrust F _combat , and at the same time, the flight parameters n _L and T ₆ obtained in step S1 are averaged. , recorded as n _{L - combat} , T _{6 - combat} , where n _L is the low pressure physical speed of the engine, and T ₆ is the engine exhaust temperature;

If in step S1, the state of the aircraft in the take-off stage is the training state take-off, then the flight parameters n _L and T ₆ obtained in step S1 are averaged, and then interpolation is performed according to the preset change relationship between the take-off thrust and the state parameters, and the interpolation value is The result is adjusted upwards until n _L or T ₆ reaches the corresponding combat state limit value, and the current combat state thrust F _combat , and the corresponding n _L-combat and T _6-combat are obtained.

Preferably, in step S4, calculating the thrust F _P at the height of the sea level includes:

Among them, P ₁ is the total pressure of the engine inlet.

Preferably, in step S4, calculating the thrust F _P at the height of the sea level includes:

Among them, H is the take-off height of the aircraft, and _Ma is the flight Mach number.

Preferably, in step S5, determining the thrust correction coefficient includes:

Using the performance simulation model of the whole machine, by adjusting the low-pressure physical speed control plan and the exhaust temperature control plan, obtain the engine thrust correction coefficients under different atmospheric temperatures, different low-pressure physical speeds, and different exhaust temperature levels, and form a thrust correction coefficient table. According to the low-pressure physical rotation speed of the engine n _L-battle and the engine exhaust temperature T _6-battle determined in step S3, interpolate in the thrust correction coefficient table to determine the corresponding thrust correction coefficient.

This application can intuitively display the change law of thrust with working time or flight sorties, replace the original way of indirectly characterizing the performance attenuation after the turbine temperature, can effectively guide users to quickly and directly grasp the engine performance level, and has a high external field Operability, on the other hand, this application avoids the problem of unclear correlation between exhaust temperature and thrust in the original evaluation method, and corrects the actual thrust to the combat thrust under standard atmospheric conditions at sea level through the corresponding correction method. level, and established a unified performance degradation evaluation benchmark.

Description of drawings

FIG. 1 is a flow chart of a preferred embodiment of a method for evaluating the performance degradation of a military aviation turbofan engine in an installed state of the present application.

FIG. 2 is a schematic diagram of a change trend of engine thrust performance attenuation in the embodiment shown in FIG. 1 of the present application.

Detailed ways

In order to make the objectives, technical solutions and advantages of the implementation of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the embodiments of the present application. Throughout the drawings, the same or similar reference numbers refer to the same or similar elements or elements having the same or similar functions. The described embodiments are some, but not all, embodiments of the present application. The embodiments described below with reference to the accompanying drawings are exemplary, and are intended to be used to explain the present application, but should not be construed as a limitation to the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application. The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

This application provides a method for evaluating the performance degradation of a military aviation turbofan engine in an installed state, as shown in Figure 1, which mainly includes:

Step S1, during the take-off period of the aircraft, the engine working state is the maximum state, and the ground speed is within the set range, and the aircraft flight parameters at each moment are acquired.

In this step, use Matlab or other data analysis tools to select the take-off period of the military aircraft, the engine working state is the maximum state, the ground speed is in the area of A km/h～B km/h, and m _fuel , a _x (or V), Variation curve of α, n _L , T ₆ and other data with time. Among them, m _fuel is the fuel quantity of the aircraft, a _x is the longitudinal acceleration of the aircraft, α is the angle of attack of the aircraft, n _L is the low-pressure physical speed of the engine, and T ₆ is the engine exhaust temperature.

It should be noted that the maximum state refers to the working state in which the maximum thrust can be continuously provided when the afterburner of the engine is working.

In some optional embodiments, the ground speed is set in a range of 140km/h to 160km/h.

Step S2, determining the take-off thrust F of a single engine at each moment based on the flight parameters of the aircraft.

In some optional embodiments, calculating the take-off thrust of a single engine includes: calculating the total engine thrust; and determining the take-off thrust of a single engine according to the number of engines. For example, for a twin-engine installation, the take-off thrust of _a single engine is F/2.

Wherein, in some optional embodiments, calculating the total engine thrust F _combined includes:

为发动机推力角。Among them, m ₀ is the weight of the take-off configuration of the aircraft, m _fuel is the fuel quantity of the aircraft, a _x is the longitudinal acceleration of the aircraft, F _resistance is the sum of the aerodynamic resistance and frictional resistance generated during the take-off process of the aircraft, α is the angle of attack of the aircraft,

is the engine thrust angle.

In an alternative embodiment, calculating _the total engine thrust F1 may also include:

为发动机推力角。Among them, m ₀ is the weight of the take-off configuration of the aircraft, m _fuel is the fuel quantity of the aircraft, V is the ground speed of the aircraft, F _resistance is the sum of the aerodynamic resistance and frictional resistance generated during the take-off process of the aircraft, α is the angle of attack of the aircraft,

is the engine thrust angle.

In addition, it should be noted that for military engines, in the area where the ground speed is A km/h ~ B km/h, the frictional resistance is small and can be basically ignored. The aerodynamic resistance is about C of the take-off thrust of a single engine in the new state. times, which can be approximated. If the aerodynamic characteristic model of the aircraft has been mastered, the detailed calculation of F resistance can be carried out, or other similar aircraft aerodynamic characteristic models can be used for calculation. Here, C is generally 3% to 5%. In the actual application process, this step is used to process the first take-off data of the new aircraft state, and the F _resistance is set to _be C times the F value, and the F _resistance is obtained as the boundary condition for the subsequent performance attenuation calculation.

Step S3, uniformly correct the take-off thrust F of a single engine to the combat state thrust F _combat , and determine the corresponding low-pressure physical engine speed n _L-combat and engine exhaust temperature T6 _-combat in the corresponding combat state.

It should be noted that when the engine is working in the maximum state, the combat state and the training state are distinguished. In the combat state, the control plans of n _L and T ₆ are higher.

In some optional embodiments, in step S3, calculating the combat state thrust F _combat includes:

If in step S1, the state of the aircraft in the take-off stage is the take-off in the combat state, then the calculated take-off thrust F of the single engine is the combat state thrust F _combat , and at the same time, the flight parameters n _L and T ₆ obtained in step S1 are averaged. , recorded as n _{L - combat} , T _{6 - combat} , where n _L is the low pressure physical speed of the engine, and T ₆ is the engine exhaust temperature;

If in step S1, the state of the aircraft in the take-off stage is the training state take-off, then the flight parameters n _L and T ₆ obtained in step S1 are averaged, and then interpolation is performed according to the preset change relationship between the take-off thrust and the state parameters, and the interpolation value is The result is adjusted upwards until n _L or T ₆ reaches the corresponding combat state limit value, and the current combat state thrust F _combat , and the corresponding n _L-combat and T _6-combat are obtained.

The second case is described here. For the engine that takes off in the training state, use the performance simulation model of the whole machine and adjust the low-pressure physical speed control plan to obtain the relationship between the take-off thrust and the state parameters under different take-off altitudes and different atmospheric temperature conditions, that is, every increase of n _L by 1. %, _T6 increases a°C, F increases b kN, as shown in Table 1. According to the average value of n _L and T ₆ obtained in step 1, through H and T ₁ , perform interpolation according to Table 1, and adjust n _L , T ₆ , and F upward according to the interpolation results of Table 1, until n _L or T ₆ reaches the corresponding The limit value of the combat status (low selection), obtain the combat status F combat, and record the corresponding n _L-battle , T _6-battle . Here _T1 is the total engine inlet temperature.

Table 1 The relationship between take-off thrust and state parameters

Step S4, the combat state thrust F combat is corrected to the thrust F _P at the height of the sea level.

In some optional embodiments, in step S4, calculating the thrust F _P at the sea level includes:

Among them, P ₁ is the total pressure of the engine inlet.

In an alternative embodiment, in step S4, calculating the thrust F _P at the height of the sea level may further include:

Among them, H is the take-off height of the aircraft, and _Ma is the flight Mach number.

Step S5, the low-pressure physical rotation speed of the engine under the combat state n _L-combat , and the engine exhaust temperature T6 _-combat determine a thrust correction coefficient, and based on the thrust correction coefficient, correct the thrust F _P at sea level to sea level Standard temperature thrust F _T .

In some optional embodiments, in step S5, determining the thrust correction coefficient includes:

Using the performance simulation model of the whole machine, by adjusting the low-pressure physical speed control plan and the exhaust temperature control plan, obtain the engine thrust correction coefficient X _F under different atmospheric temperatures, different low-pressure physical speeds, and different exhaust temperature levels, and form a thrust correction coefficient table , as shown in Table 2, then according to the low-pressure physical speed of the engine nL _-combat determined in step S3, and the engine exhaust temperature T6 _-combat , interpolate in the thrust correction coefficient table to determine the corresponding thrust correction coefficient. Wherein, F _T =F _P ×X _F .

Table 2 Sea level standard temperature thrust correction coefficient table

Among them, ΔT is the temperature deviation between the engine intake air temperature and the sea level standard temperature of 15°C.

Step S6, establish the relationship curve of sea level standard temperature thrust F _T with flight sorties or flight time, and form the engine thrust performance attenuation change trend, as shown in Figure 2, the engine thrust performance attenuation change trend is used to characterize the aviation turbofan engine The degree of performance degradation.

This application can intuitively display the change law of thrust with working time or flight sorties, replace the original way of indirectly characterizing the performance attenuation after the turbine temperature, can effectively guide users to quickly and directly grasp the engine performance level, and has a high external field Operability, on the other hand, this application avoids the problem of unclear correlation between exhaust temperature and thrust in the original evaluation method, and corrects the actual thrust to the combat thrust under standard atmospheric conditions at sea level through the corresponding correction method. level, and established a unified performance degradation evaluation benchmark.

Although the present application has been described in detail above with general description and specific embodiments, some modifications or improvements can be made on the basis of the present application, which will be obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present application fall within the scope of protection claimed in the present application.

Claims (9)

1. A method of evaluating performance degradation of a military aviation turbofan engine during an installed condition, comprising:

s1, acquiring airplane flight parameters at each moment when the working state of an engine is the maximum state and the ground speed is within a set range in the takeoff period of an airplane;

s2, determining the takeoff thrust F of a single engine at each moment based on the flight parameters of the airplane;

s3, uniformly correcting the takeoff thrust F of the single engine to the fighting state thrust F _Combat And determining the corresponding low-pressure physical rotating speed n of the engine under the fighting state _L-battle And engine exhaust temperature T _6-battle ；

Step S4, pushing force F of fighting state _Combat Thrust F corrected to sea level _P ；

S5, according to the low-pressure physical rotating speed n of the engine in the fighting state _L-battle And engine exhaust temperature T _6-battle Determining a thrust correction factor and applying a thrust F at sea level altitude based on said thrust correction factor _P Corrected to sea level standard temperature thrust F _T ；

Step S6, establishing sea level standard temperature thrust F _T And forming an engine thrust performance attenuation variation trend along with a relationship curve of the flight number or the flight time, wherein the engine thrust performance attenuation variation trend is used for representing the performance attenuation degree of the aviation turbofan engine.

2. The method for estimating the performance degradation of a military aviation turbofan engine in an installed state according to claim 1, wherein in step S1, the ground speed is set within a range of 140km/h to 160km/h.

3. The method for evaluating the performance degradation of a military aviation turbofan engine in an installed state according to claim 1 wherein the step S2 of calculating the takeoff thrust of the single engine comprises:

calculating the total engine thrust;

and determining the takeoff thrust of a single engine according to the number of the engines.

4. The method of claim 3, wherein the total engine thrust F is calculated _{Combination of Chinese herbs} The method comprises the following steps:

wherein m is ₀ Weight, m, for aircraft takeoff configuration _fuel For aircraft oil content, a _x For aircraft longitudinal acceleration, F _{Resistance device} Is the sum of aerodynamic drag and frictional drag generated in the takeoff process of the airplane, alpha is the attack angle of the airplane,

is the engine thrust angle.

5. The method of estimating military aviation turbofan engine performance degradation at the installed state of claim 3 wherein calculating total engine thrust comprises:

wherein m is ₀ Weight, m, for aircraft takeoff configuration _fuel Aircraft oil quantity, V aircraft ground speed, F _{Resistance device} Is the sum of aerodynamic drag and frictional drag generated in the takeoff process of the airplane, alpha is the attack angle of the airplane,

is the engine thrust angle.

6. The method for estimating military aviation turbofan engine performance degradation at the installation state of claim 1 wherein in step S3, a combat state thrust F is calculated _Combat The method comprises the following steps:

if step S is performed1, if the takeoff state of the airplane is the fighting state takeoff, the calculated takeoff thrust F of the single engine is the fighting state thrust F _Combat At the same time, the flight parameter n obtained in step S1 is corrected _L 、T ₆ Take the average and record as n _L-battle 、T _6-battle Wherein n is _L For low-pressure physical speed of engine, T ₆ Is the engine exhaust temperature;

if the state of the takeoff stage of the airplane in the step S1 is the training state takeoff, the flight parameter n acquired in the step S1 _L 、T ₆ Taking an average value, then carrying out interpolation according to the change relation between the preset takeoff thrust and the state parameters, and upwards adjusting the interpolation result until n _L Or T ₆ The corresponding limit value of the fighting state is reached, and the fighting state thrust F at the moment is obtained _Combat And corresponding n _L-battle 、T _6-battle 。

7. The method for on-line evaluation of performance decay in a military aviation turbofan engine of claim 1 wherein in step S4, thrust F at sea level is calculated _P The method comprises the following steps:

wherein, P ₁ Is the total engine inlet pressure.

8. The method for estimating performance degradation of a military aviation turbofan engine in an installed state according to claim 1 wherein in step S4, thrust F at sea level is calculated _P The method comprises the following steps:

wherein H is the takeoff height of the airplane, M _a The flight mach number.

9. The method for estimating performance degradation of a military aviation turbofan engine under installation as claimed in claim 1 wherein determining thrust correction factors in step S5 comprises:

using a complete machine performance simulation model, obtaining engine thrust correction coefficients under different atmospheric temperatures, different low-pressure physical rotating speeds and different exhaust temperature levels by adjusting a low-pressure physical rotating speed control plan and an exhaust temperature control plan to form a thrust correction coefficient table, and then determining the low-pressure physical rotating speed n of the engine according to the step S3 _L-battle And engine exhaust temperature T _6-battle And interpolating in the thrust correction coefficient table to determine a corresponding thrust correction coefficient.

Images