A method for evaluating the effect of sand and dust erosion on the performance of turboshaft engines

Abstract

The present invention relates to the technical field of aviation turboshaft engines, and provides an evaluation method for the influence of sand and dust erosion and wear on the performance of turboshaft engines, comprising: calculating the amount of sand and dust sucked into the turboshaft engine; using computational fluid dynamics software to calculate and solve the airflow field in the compressor channel and the motion trajectory of sand and dust particles; establishing a mathematical model of sand and dust erosion and wear on the compressor blades of the turboshaft engine; based on the motion trajectory and the mathematical model, obtaining the blade profile of the worn blade, further calculating and solving the airflow field inside the compressor channel after wear, and obtaining the decrease in compressor efficiency after sand and dust erosion and wear; based on the decrease in compressor efficiency, using engine overall performance calculation software to calculate and evaluate the change in engine performance parameters. The present invention proposes a set of turboshaft engine performance attenuation evaluation methods by constructing a mathematical model of compressor blade wear, and realizes quantitative analysis and evaluation of turboshaft engine performance attenuation in a sand and dust environment.

Description

Technical Field

[0001] The invention relates to the technical field of aviation turboshaft engines, and in particular to a method for evaluating the influence of sand and dust erosion and wear on the performance of turboshaft engines. Background Art

[0002] The widespread dust environment has a serious impact on the helicopter's components, systems, onboard equipment, and especially the engine. The consequences of dust being swallowed by the turboshaft engine are: compressor blade corrosion and the resulting deterioration of engine performance, which ultimately shortens the engine's service life.

[0003] Under the influence of natural wind and rotor-induced downwash, the sand and dust carried by strong wind can wear the helicopter's moving parts and fixed outer surfaces, and the sand and dust entering the turboshaft engine will wear and corrode the compressor and turbine blades. Long-term operation in a dusty environment will cause particularly obvious damage to the compressor blades of turboshaft engines, with wear on the leading edge of the blades and increased tip clearance, which will eventually lead to degradation of compressor performance, reduced efficiency, and reduced engine power. When blade wear reaches a certain level, it will induce turboshaft engine surge and shutdown, seriously endangering flight safety and helicopter serviceability.

[0004] Erosion refers to a type of progressive wear on the surface of a material caused by the impact of solid particles carried by air or liquid. The erosion damage suffered by the material can be divided into three categories according to the impact speed of the sand and dust: low speed, medium speed and high speed. In the past, domestic and foreign research work mainly focused on the sand and dust erosion of metal materials under low-speed conditions. For aircraft engines, when the high-speed rotating blades collide with the sand and dust, the relative collision speed of the two will exceed 300m / s, which belongs to the category of high-speed erosion. The existing low-speed erosion theory is difficult to apply to the high-speed erosion conditions of rotor blades such as compressors. In addition, in the research work on the in-service use and safety issues of helicopter turboshaft engines, an engineering method that can quantitatively evaluate the impact of sand and dust erosion wear on the performance of turboshaft engines is also needed.

[0005] Existing methods for evaluating turboshaft engine performance degradation mostly use flight parameter data or numerical simulation-based methods. However, there is a lack of methods that can quantitatively evaluate the impact of dust erosion and wear on the overall performance of turboshaft engines from an engineering perspective, targeting typical problems such as blade wear and performance degradation caused by turboshaft engines working in dusty environments. Summary of the invention

[0006] The purpose of the present invention is to solve at least one technical problem in the background technology and to provide a method for evaluating the influence of sand and dust erosion and wear on the performance of a turboshaft engine.

[0007] To achieve the above object, the present invention provides a method for evaluating the effect of sand and dust erosion and wear on the performance of a turboshaft engine, comprising:

[0008] Given the air flow rate of the turboshaft engine and the material properties of the inhaled sand and dust, calculate the amount of sand and dust inhaled into the turboshaft engine;

[0009] Based on the mathematical model of dilute gas-solid two-phase flow, computational fluid dynamics software is used to calculate the air flow field in the compressor channel and the movement trajectory of sand and dust particles;

[0010] Establish a mathematical model of dust erosion and wear on compressor blades of turboshaft engines;

[0011] Based on the motion trajectory and the mathematical model, the blade profile of the worn blade is obtained, and the airflow field inside the compressor channel after the wear is further calculated and solved to obtain the decrease in compressor efficiency after sand and dust erosion wear;

[0012] Based on the decrease in compressor efficiency, engine overall performance calculation software is used to calculate and evaluate changes in engine performance parameters.

[0013] According to one aspect of the present invention, the step of calculating the amount of sand and dust sucked into the turboshaft engine comprises:

[0014] Calculate the mass of sand and dust entering the compressor per unit time:

[0015] ;

[0016] Where: is the mass of sand and dust sucked by the engine per unit time; is the overall environmental severity index; is the mass of air entering the engine per unit time; is the density of air; is the statistical average volume of each local dust particle; is the density of local dust;

[0017] Integrate to obtain the accumulated dust mass entering the compressor at a certain spatial position and time point :

[0018] .

[0019] According to one aspect of the present invention, the method of using computational fluid dynamics software to calculate and solve the airflow field in the compressor channel and the motion trajectory of sand and dust particles includes:

[0020] The momentum change rate after the collision is expressed by the normal and tangential velocity restitution coefficients before and after the collision:

[0021] ;

[0022] ;

[0023] Where: are the normal velocities of the particles before and after collision, are the tangential velocities of the particles before and after collision, respectively; is the incident angle of the particles impacting the inner wall of the turboshaft engine.

[0024] According to one aspect of the present invention, the method of establishing a mathematical model of dust wear on turbine shaft engine blades includes:

[0025] The mass loss of the blade after the inhalation of unit mass of sand and dust erosion is defined as the wear rate The wear rate is obtained based on the experimental data and theoretical analysis of Tabakoff and Grand The empirical formula is:

[0026] ;

[0027] ;

[0028] ;

[0029] ;

[0030] ;

[0031] Where: is the incident angle corresponding to the maximum wear rate; , , is the reference speed, where , , , is the particle impact velocity, , , , , is an empirical constant related to the material properties of the compressor blades and the incident particles.

[0032] According to one aspect of the present invention, based on the motion trajectory and the mathematical model, the blade profile of the worn blade is obtained, and the airflow field inside the worn compressor channel is further calculated and solved to obtain the decrease in compressor efficiency after sand and dust erosion wear, including:

[0033] According to the movement trajectory of the sand and dust particles and the mathematical model of the blade erosion wear, the incident angle and speed of the sand and dust particles hitting the blade are obtained, the wear amount of the sand and dust particles on the compressor blade per unit time is calculated, and the blade profile of the worn blade is obtained;

[0034] Based on the blade profile, computational fluid dynamics software is used to numerically solve the airflow field inside the compressor channel to obtain the efficiency of the compressor after wear, and the efficiency is compared with the efficiency of the compressor before wear to obtain the decrease in efficiency.

[0035] According to one aspect of the present invention, the engine performance parameters include gas turbine power, shaft power and fuel consumption rate.

[0036] According to the solution of the present invention, the present invention effectively solves the following technical problems:

[0037] (1) How to determine the amount of dust inhaled into a turboshaft engine; (2) How to quantitatively evaluate the impact of blade wear on compressor efficiency; (3) How to quantitatively evaluate the impact of reduced compressor efficiency caused by dust erosion wear on turboshaft engine performance.

[0038] According to the solution of the present invention, in order to solve the problems of blade wear and air path blockage of turboshaft engines in dusty working environments, combined with the structure and usage characteristics of helicopters and turboshaft engines, an environmental severity index and a dilute gas-solid two-phase flow analysis method are introduced. By constructing a mathematical model of compressor blade wear, a set of turboshaft engine performance attenuation evaluation methods is proposed, which realizes the quantitative analysis and evaluation of turboshaft engine performance attenuation in dusty environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A flow chart schematically shows a method for evaluating the effect of dust erosion and wear on the performance of a turboshaft engine according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The present invention will now be discussed with reference to exemplary embodiments. It should be understood that the embodiments discussed are only to enable those skilled in the art to better understand and thus implement the present invention, rather than implying any limitation on the scope of the present invention.

[0041] As used herein, the term “including” and variations thereof are to be interpreted as open-ended terms meaning “including, but not limited to.” The term “based on” is to be interpreted as “based, at least in part, on.” The terms “one embodiment” and “an embodiment” are to be interpreted as “at least one embodiment.”

[0042] Figure 1A flow chart schematically shows a method for evaluating the effect of sand erosion wear on the performance of a turboshaft engine according to an embodiment of the present invention. Figure 1 As shown, in this embodiment, the method for evaluating the effect of sand and dust erosion and wear on the performance of a turboshaft engine includes:

[0043] Given the air flow rate of the turboshaft engine and the material properties of the inhaled sand and dust, calculate the amount of sand and dust inhaled into the turboshaft engine;

[0044] Based on the mathematical model of dilute gas-solid two-phase flow, computational fluid dynamics software is used to calculate the air flow field in the compressor channel and the movement trajectory of sand and dust particles;

[0045] Establish a mathematical model of dust erosion and wear on compressor blades of turboshaft engines;

[0046] Based on the motion trajectory and mathematical model, the blade profile of the worn blade is obtained, and the airflow field inside the compressor channel after wear is further calculated and solved to obtain the decrease in compressor efficiency after sand and dust erosion wear.

[0047] Based on the decrease in compressor efficiency, the engine overall performance calculation software is used to calculate and evaluate the changes in engine performance parameters.

[0048] Further, according to one embodiment of the present invention, when a helicopter is operating in a dusty environment, for example, dust particles may enter the turboshaft engine and affect the compressor blades. Natural wind blows up the dust particles and transports them to the engine inlet. In addition, the helicopter downwash increases the dust concentration in the environment, and the dust particles entering the engine increase dramatically. Introducing the environmental severity index , used to measure at a given spatial position and instantaneous The amount of dust carried in the air indicates the number of dust particles contained in a unit volume of air at this spatial location. A measure of the overall local environmental severity, including dust and sand introduced into the ambient air by natural winds and helicopter downwash.

[0049] According to the above definition, the severity index of the helicopter flight environment is The flight time varies depending on the route and time of flight. During the flight, the helicopter needs to be equipped with a sensor that can measure the environmental severity index in real time. If there is no dust inhalation sensor, the dust particle size distribution and density in the flight environment can be analyzed, and the dust concentration inhaled into the engine can be measured in real time to calculate the severity index of the environment. .

[0050] In this embodiment, in order to determine the total mass of sand and dust entering the compressor, the instantaneous mass of sand and dust entering the compressor per unit time is first required, and the following formula is used for calculation:

[0051] ;

[0052] Where: is the mass of sand and dust sucked by the engine per unit time; is the overall environmental severity index; is the mass of air entering the engine per unit time; is the density of air; is the statistical average volume of each local dust particle; is the density of local dust.

[0053] Then, the accumulated dust mass entering the compressor at a certain spatial position and time point is obtained by integration. :

[0054] .

[0055] Further, according to one embodiment of the present invention, computational fluid dynamics software is used to calculate the airflow field in the compressor channel and the motion trajectory of the sand and dust particles as follows:

[0056] The motion equation of sand and dust particles in the compressor blade channel is analyzed. The movement of sand and dust particles in the compressor blade channel belongs to dilute gas-solid two-phase flow. Generally, the flow process of the gas is calculated through numerical simulation to obtain the flow field distribution of the gas in the compressor channel; then the solid particles are released, the motion equation of each sand and dust particle is solved, and its motion trajectory is studied.

[0057] Specifically, before solving the motion trajectory of sand and dust particles, in order to reasonably simplify the calculation workload, the following basic assumptions are made:

[0058] (1) The sand and dust particles entering the compressor are evenly distributed;

[0059] (2) The sand and dust particles are spherical in shape;

[0060] (3) The density of sand and dust particles is uniform;

[0061] (4) The dust particles are very small and the mass force can be ignored;

[0062] (5) The presence of sand and dust particles does not change the motion properties of the gas;

[0063] (6) The forces acting on sand and dust particles are mainly aerodynamic drag, centrifugal force and Coriolis force.

[0064] In this embodiment, for incompressible fluids, almost all fluid calculations are achieved by solving the continuity equation and the Navier-Stokes equations. These equations can be expressed using a general formula, and the general form is as follows:

[0065] ;

[0066] Where: is a universal variable that can be expressed as 、v、 , etc. to solve for variables; is the generalized diffusion coefficient; is a generalized source term.

[0067] Furthermore, in this embodiment, considering that the airflow field in the compressor channel is relatively complex and is accompanied by aerodynamic phenomena such as flow separation, strong bending flow, and bifurcated flow, this method uses the Realizable k-ε turbulence model in numerical simulation calculations.

[0068] Furthermore, in this embodiment, the force motion equation of the solid particles is:

[0069] ;

[0070] Where: is the particle impact velocity; is the gas velocity; is the particle density; is the gas density; is the gravitational acceleration; is the viscous resistance, ,in is the relative Reynolds number of the particle, is the gas dynamic viscosity, is the particle size of the sieved particles, is the drag coefficient; It is the sum of the external forces acting on the particles in the flow field.

[0071] Furthermore, in this embodiment, due to the curved profile of the flow channel inside the compressor, the sand and dust particles collide with the wall surface due to the influence of centrifugal force and inertial force. Since the collision between the particles and the wall surface is a non-completely elastic collision, the particles rebound after colliding with the wall surface, and the reflection angle of the particles after rebounding is smaller than the incident angle, and the reflectivity is smaller than the incidence.

[0072] Therefore, there must be energy loss after the particles collide, and the momentum change rate after the collision is represented by the normal and tangential velocity restitution coefficients before and after the collision. The normal and tangential velocity restitution coefficients used in the present invention are calculated as follows:

[0073] ;

[0074] ;

[0075] Where: are the normal velocities of the particles before and after collision, are the tangential velocities of the particles before and after collision, respectively; is the incident angle of the particle impacting the wall, in radians (rad).

[0076] Furthermore, according to one embodiment of the present invention, due to the collision and friction between the surface of air path components such as compressor blades and harder and larger particles in the airflow, erosion spots and grinding will be formed on the blades, increasing the roughness of the blade surface, thereby causing the aerodynamic performance of the compressor blades to deteriorate. Therefore, the present invention establishes a mathematical model of the wear of engine blades by sand and dust based on the micro-cutting theory. Specifically, the mass loss rate of the blades due to wear is a complex function of multiple variables, which is related to factors such as the material of the blades, the physical properties of the sand and dust particles, the particle size, the angle of incidence and the speed. The present invention defines the mass loss of the blades after the erosion of a unit mass of dust particles is inhaled as the wear rate The wear rate is obtained based on the experimental data and theoretical analysis of Tabakoff and Grand The empirical formula is:

[0077] ;

[0078] ;

[0079] ;

[0080] ;

[0081] ;

[0082] Where: is the incident angle corresponding to the maximum wear rate; , , is the reference speed, which are defined as , , , , , , , is an empirical constant related to the material properties of the compressor blades and the incident particles;

[0083] Furthermore, in this embodiment, for the determined compressor blades and sand and dust particle materials, the incident angle and speed of the sand and dust particles hitting the blades are obtained, and the wear amount of a single sand and dust particle on the compressor blade can be calculated. To simplify the calculation, given the dust concentration in the air and the dust particle size, the flow of the sand-containing airflow in the two-dimensional plane cascade of the compressor is analyzed, the wear amount of the sand and dust on the blade over a period of time is calculated, the blade profile of the blade after wear is obtained, and the efficiency of the compressor after sand and dust erosion wear is calculated with the help of computational fluid dynamics (CFD) software.

[0084] Furthermore, in this embodiment, the amount of sand and dust transported in the compressor channel is calculated; based on the mathematical model constructed above, the airflow field and the movement trajectory of the sand and dust particles in the compressor channel are numerically simulated, and the decrease in compressor efficiency caused by the wear of the sand and dust particles is obtained; GasTurb and other software are used to quantitatively analyze the impact of the decrease in compressor efficiency on the performance of the turboshaft engine, focusing on the changes in parameters such as gas turbine power, shaft power, and fuel consumption rate.

[0085] Specifically, according to an embodiment of the present invention, based on the motion trajectory and the mathematical model, the blade profile of the worn blade is obtained, and the airflow field inside the worn compressor channel is further calculated and solved to obtain the decrease in compressor efficiency after sand and dust erosion wear, including:

[0086] According to the movement trajectory of the sand and dust particles and the mathematical model of the blade erosion wear, the incident angle and speed of the sand and dust particles hitting the blade are obtained, the wear amount of the sand and dust particles on the compressor blade per unit time is calculated, and the blade profile of the worn blade is obtained;

[0087] Based on the obtained blade profile, computational fluid dynamics software is used to numerically solve the airflow field inside the compressor channel to obtain the efficiency of the compressor after wear, and then compare it with the efficiency of the compressor before wear to obtain the efficiency drop.

[0088] According to the above solution of the present invention, the present invention effectively solves the following technical problems:

[0089] (1) How to determine the amount of dust inhaled into a turboshaft engine; (2) How to quantitatively evaluate the impact of blade wear on compressor efficiency; (3) How to quantitatively evaluate the impact of reduced compressor efficiency caused by dust erosion wear on turboshaft engine performance.

[0090] According to the above scheme of the present invention, in order to solve the problems of blade wear and air path blockage of turboshaft engines in dusty working environments, combined with the structure and usage characteristics of helicopters and turboshaft engines, an environmental severity index and a dilute gas-solid two-phase flow analysis method are introduced. By constructing a mathematical model of compressor blade wear, a set of turboshaft engine performance attenuation evaluation methods is proposed, which realizes the quantitative analysis and evaluation of the performance attenuation of turboshaft engines in dusty environments.

[0091] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other.

[0092] It should be understood that the size of the serial numbers of each step in the content of the invention and the implementation methods of the present invention does not absolutely mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation methods of the present invention.

Claims

1. A method for evaluating the effect of sand and dust erosion and wear on the performance of a turboshaft engine, characterized in that: include: Given the air flow rate of the turboshaft engine and the material properties of the inhaled sand and dust, calculate the amount of sand and dust inhaled into the turboshaft engine; Based on the mathematical model of dilute gas-solid two-phase flow, computational fluid dynamics software is used to calculate the air flow field in the compressor channel and the movement trajectory of sand and dust particles; Establish a mathematical model of dust erosion and wear on compressor blades of turboshaft engines; Based on the motion trajectory and the mathematical model, the blade profile of the worn blade is obtained, and the airflow field inside the compressor channel after the wear is further calculated and solved to obtain the decrease in compressor efficiency after sand and dust erosion wear; Based on the decrease in compressor efficiency, engine overall performance calculation software is used to calculate and evaluate changes in engine performance parameters; The method of calculating the amount of sand and dust sucked into the turboshaft engine comprises: Calculate the mass of sand and dust entering the compressor per unit time: ； Where: is the mass of sand and dust sucked by the engine per unit time; It is the overall environmental severity index, which is used to measure the amount of sand and dust propagating in the air at a given spatial location and instant t, and represents the number of dust particles contained in a unit volume of air in this space; is the mass of air entering the engine per unit time; is the density of air; is the statistical average volume of each local dust particle; is the density of each dust particle in the local area; Integrate to obtain the accumulated dust mass entering the compressor at a certain spatial position and time point : ； Based on the motion trajectory and the mathematical model, the blade profile of the worn blade is obtained, and the airflow field inside the worn compressor channel is further calculated and solved to obtain the decrease in compressor efficiency after sand and dust erosion wear, including: According to the movement trajectory of the sand and dust particles and the mathematical model of the blade erosion wear, the incident angle and speed of the sand and dust particles hitting the blade are obtained, the wear amount of the sand and dust particles on the compressor blade per unit time is calculated, and the blade profile of the worn blade is obtained; Based on the blade profile, computational fluid dynamics software is used to numerically solve the airflow field inside the compressor channel to obtain the efficiency of the compressor after wear, and the efficiency is compared with the efficiency of the compressor before wear to obtain the decrease in efficiency.

2. The method for evaluating the effect of sand and dust erosion and wear on the performance of a turboshaft engine according to claim 1, characterized in that: The method of using computational fluid dynamics software to calculate and solve the airflow field in the compressor channel and the motion trajectory of sand and dust particles includes: The normal and tangential velocity restitution coefficients before and after the dust particles collide with the compressor blades represent the rate of change of momentum after the collision: ； ； Where: are the normal velocities of the particles before and after collision, respectively. are the tangential velocities of the particles before and after collision, respectively; is the incident angle of the particle impacting the blade.

3. The method for evaluating the effect of sand and dust erosion and wear on the performance of a turboshaft engine according to claim 1, characterized in that: The method of establishing a mathematical model for the erosion and wear of compressor blades of a turboshaft engine by sand and dust comprises: The mass loss of the blade after the erosion of unit mass of sand and dust is defined as the wear rate E. The empirical formula of the wear rate E is derived by Tabakoff and Grand based on experimental data and theoretical analysis: ； ； ； ； ； Where: is the incident angle corresponding to the maximum wear rate; , , is the reference speed, where , , , is the particle impact velocity, , , , , is an empirical constant related to the material properties of the compressor blades and the incident particles.

4. The method for evaluating the effect of sand erosion and wear on the performance of a turboshaft engine according to any one of claims 1 to 3, characterized in that: The engine performance parameters include gas turbine power, shaft power and fuel consumption rate.

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