CN-122020914-A - Performance map construction method and system of mixed flow turbine under pulsation condition

CN122020914ACN 122020914 ACN122020914 ACN 122020914ACN-122020914-A

Abstract

The invention relates to the technical field of turbomachinery and engine supercharging, in particular to a method and a system for constructing a performance map of a mixed flow turbine under a pulsation condition, aiming at the defects that a traditional steady-state map cannot reflect pulsation transient behavior, a negative work interval and the like, instantaneous operation parameters of the turbine are obtained through a pulsation flow generating device, quasi-steady-state data points are screened based on a local unsteady criterion, and (3) generating a wide-working-condition flow swallowing capacity map by adopting an improved flow swallowing capacity model containing pseudo specific heat ratio correction, constructing an efficiency map containing a negative efficiency region by using an average line loss model taking isentropic enthalpy drop as a reference, and integrating the efficiency map into a one-dimensional simulation model of the engine through association and fusion of a uniform working-condition coordinate system. The complete rotating speed line can be generated through single pulsation measurement, the negative work behavior and unsteady mechanical loss can be accurately represented, the working condition coverage range is widened, the extrapolation error is reduced, the transient performance prediction precision of the turbocharging system is improved, and the method is suitable for low-frequency large pulsation and cylinder shock modes.

Inventors

LIU ZHENG
Shi Yeqi
ZHANG TAO
ZHU CHUANG

Assignees

杭州玄材科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260408

Claims (10)

1. The method for constructing the performance map of the mixed-flow turbine under the pulsation condition is characterized by comprising the following steps of: Acquiring transient operation parameters of the turbine under the pulsating air intake condition, screening quasi-steady state data points for constructing a performance map from the transient operation parameters based on quasi-steady state judgment criteria, and forming a basic data set for constructing the map; Based on the quasi-steady-state data points, performing parameter fitting and extrapolation by adopting an improved turbine flow-swallowing capacity model to generate a turbine flow-swallowing capacity characteristic map covering a wide working condition range; Based on the quasi-steady state data points, performing model calibration and calculation by adopting an average line loss model capable of representing a negative efficiency phenomenon, and generating a turbine efficiency characteristic map containing a negative efficiency region; Correlating and fusing the characteristic spectrum of the turbine flow swallowing capacity and the characteristic spectrum of the turbine efficiency under a uniform working condition coordinate system to generate a comprehensive turbine performance spectrum; the integrated turbine performance map is integrated into an engine simulation model for simulating transient operating performance of the turbine under pulsating exhaust conditions.
2. The method of claim 1, wherein the step of screening quasi-steady state data points from the instantaneous operating parameters for building a performance map comprises: measuring and recording transient operating parameters of the turbine under simulated pulsation conditions on a turbine test bench; calculating an instantaneous unsteady degree index representing the unsteady degree of the internal flow of the turbine at each sampling moment according to the measured instantaneous operation parameters; setting a quasi-steady state judgment threshold value, and determining data corresponding to sampling moments of which the instantaneous unsteady degree index is smaller than the threshold value as quasi-steady state data points; all quasi-steady state data points are extracted and arranged to form a basic data set organized according to different turbine expansion ratios and turbine reduced rotation speeds.
3. The method for constructing a mixed-flow turbine performance map under pulsating conditions according to claim 1, wherein the step of generating a turbine flow swallowing capacity characteristic map covering a wide range of operating conditions comprises: constructing a modified mathematical model of the turbine flow-swallowing capacity based on the principle of the isentropic nozzle; inputting the basic data set into the mathematical model, and fitting and determining rotation speed related parameters in the model; calculating a turbine folded mass flow predicted value under a series of continuous working condition points in a target working condition range based on the fitted mathematical model; and drawing a characteristic curve according to the flow predicted value, and compiling a complete characteristic map of the flow capacity of the turbine.
4. The method of constructing a performance map of a mixed-flow turbine under pulsating conditions according to claim 1, wherein the step of generating a turbine efficiency characteristic map including a negative efficiency region comprises: constructing an average line loss analysis model of the turbine through-flow part, wherein the model calculates mechanical efficiency by taking isentropic enthalpy drop as a reference; Setting in the model that the calculation result of the mechanical efficiency is allowed to be negative when the sum of the losses flowing through the turbine exceeds the isentropic enthalpy drop; Calibrating a loss coefficient in the model by using the quasi-steady state data points; and calculating the turbine mechanical efficiency under different working conditions by using the calibrated model, and generating a turbine efficiency characteristic map containing a negative efficiency region.
5. The method of constructing a mixed-flow turbine performance map under pulsating conditions of claim 1, wherein the step of generating a composite turbine performance map comprises: defining a two-dimensional turbine working condition coordinate system taking a turbine expansion ratio and a turbine folding rotational speed as coordinate axes; Mapping all data curves in the turbine flow swallowing capacity characteristic map and the turbine efficiency characteristic map into the two-dimensional working condition coordinate system respectively; Carrying out data association processing on the data curves mapped to the same coordinate system, and ensuring that each working condition point corresponds to a unique turbine folded mass flow value and a turbomachine efficiency value; and integrating the two types of data after association into a comprehensive turbine performance map with a unified data structure.
6. The method for constructing a performance map of a mixed-flow turbine under pulsating conditions according to claim 1, wherein the step of simulating transient operation performance of the turbine under pulsating exhaust conditions comprises: Converting the comprehensive turbine performance map into a standard table look-up format; the converted map data is used as a performance data source of the turbine component module and is imported into engine simulation software; in the simulation operation, performing bivariate interpolation query in the comprehensive map according to the real-time working condition parameters to obtain corresponding turbine performance parameters; and calculating the real-time power of the turbine based on the turbine performance parameters obtained by inquiry, feeding the real-time power back to a turbocharger shafting dynamics model, driving a simulation process, and completing the prediction of the transient performance of the turbine.
7. A system for constructing a performance map of a mixed-flow turbine under pulsating conditions, comprising: The acquisition module is used for acquiring instantaneous operation parameters of the turbine under the pulsating air inlet condition, screening quasi-steady state data points for constructing a performance map from the instantaneous operation parameters based on a quasi-steady state judgment criterion, and forming a basic data set for constructing the map; The first generation module is used for carrying out parameter fitting and extrapolation by adopting an improved turbine flow capacity model based on the quasi-steady-state data points to generate a turbine flow capacity characteristic map covering a wide working condition range; The second generation module is used for carrying out model calibration and calculation by adopting an average line loss model capable of representing a negative efficiency phenomenon based on the quasi-steady state data points, and generating a turbine efficiency characteristic map containing a negative efficiency region; The fusion module is used for correlating and fusing the characteristic spectrum of the turbine flow swallowing capacity and the characteristic spectrum of the turbine efficiency under a uniform working condition coordinate system to generate a comprehensive turbine performance spectrum; And the simulation module is used for integrating the comprehensive turbine performance map into an engine simulation model and simulating the transient working performance of the turbine under the condition of pulsating exhaust.
8. The mixed flow turbine performance map building system under pulsating conditions of claim 7, wherein the second generation module comprises: A construction unit for constructing an average line loss analysis model of the turbine through-flow portion, the model calculating mechanical efficiency with isentropic enthalpy drop as a reference; an analysis unit for setting, in the model, that allows the calculation result of the mechanical efficiency to be negative when the sum of the losses flowing through the turbine exceeds the isentropic enthalpy drop; The calibration unit is used for calibrating the loss coefficient in the model by utilizing the quasi-steady state data points; and the generating unit is used for calculating the turbine mechanical efficiency under different working conditions by using the calibrated model and generating a turbine efficiency characteristic map containing a negative efficiency region.
9. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the method of any of claims 1 to 6 when the computer program is executed.
10. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 1 to 6.

Description

Performance map construction method and system of mixed flow turbine under pulsation condition Technical Field The invention relates to the technical field of turbomachinery and engine supercharging, in particular to a method and a system for constructing a performance map of a mixed flow turbine under a pulsation condition. Background The mixed flow turbine has the advantages of high efficiency, wide working condition adaptability and the like, and is widely applied to an engine supercharger system, and the working performance of the mixed flow turbine directly determines the response speed and the energy conversion efficiency of the supercharger, so that the power output, the fuel economy and the emission index of the engine are affected. However, when the turbine is actually installed and operated, the turbine is always in an exhaust pulsating flow environment caused by the periodic opening and closing of an engine valve and the reciprocating motion of a piston, and the pulsating flow can cause the internal flow of the turbine to show obvious unsteady characteristics, and the phenomena of flow lag, pressure/temperature peak value deviation, severe fluctuation of instantaneous load and the like are represented. At present, a traditional gas rack steady-state testing method is generally adopted in the industry to construct a turbine performance map, namely, a test is carried out by controlling steady-state boundary conditions, and then test data are extrapolated based on an empirical model so as to cover a wider working condition range. However, the traditional method has a plurality of outstanding defects that the method is difficult to adapt to the turbine performance characterization requirement in a pulsating flow environment, a steady-state test cannot capture transient behaviors in a pulsating cycle, a constructed map cannot reflect the actual working state of a turbine in a real pulsating environment, so that the deviation between the simulation of a supercharger based on the map and the actual working condition exists, the turbine can generate a free rotation or even a negative work state of acting reversely in a low-pressure section of the pulsating cycle, at the moment, the turbine power is negative, but the traditional steady-state method cannot acquire data in the negative work section at all, so that map information is incomplete, the pressure ratio and flow range of a steady-state test point are limited, extreme working conditions such as critical flow, low-pressure ratio free rotation and the like cannot be directly measured, error accumulation is easy to generate when the experimental model is relied on extrapolation, and the map precision is further reduced. The defects directly cause that the prediction deviation of the turbine rotating speed and the compressor power of the traditional map is obvious in the simulation of the pulse condition supercharger, and especially in a low-frequency large-amplitude pulse or cylinder shock mode, the error exceeds the acceptable range of engineering application, the matching optimization effect of an engine and the supercharger is seriously affected, and the further development of the supercharging technology is restricted. Therefore, there is a need for a method and system for constructing a mixed-flow turbine performance map under pulsating conditions to solve the above-mentioned problems. Disclosure of Invention The invention aims to provide a method for constructing a performance map of a mixed-flow turbine under a pulsation condition, which comprises the following steps: Acquiring transient operation parameters of the turbine under the pulsating air intake condition, screening quasi-steady state data points for constructing a performance map from the transient operation parameters based on quasi-steady state judgment criteria, and forming a basic data set for constructing the map; Based on the quasi-steady-state data points, performing parameter fitting and extrapolation by adopting an improved turbine flow-swallowing capacity model to generate a turbine flow-swallowing capacity characteristic map covering a wide working condition range; Based on the quasi-steady state data points, performing model calibration and calculation by adopting an average line loss model capable of representing a negative efficiency phenomenon, and generating a turbine efficiency characteristic map containing a negative efficiency region; Correlating and fusing the characteristic spectrum of the turbine flow swallowing capacity and the characteristic spectrum of the turbine efficiency under a uniform working condition coordinate system to generate a comprehensive turbine performance spectrum; the integrated turbine performance map is integrated into an engine simulation model for simulating transient operating performance of the turbine under pulsating exhaust conditions. Furthermore, the invention also discloses a system for constructing the performance map of the mixed