A test calculation formula and evaluation method for supercharger characteristics of internal combustion engines

Abstract

The application provides a supercharger characteristic test calculation formula and evaluation method special for internal combustion engine, relates to the technical field of new energy internal combustion engine, and executes according to the following logic in sequence: basic parameter input, calculation of compressor thermodynamic characteristic parameters, calculation of turbine flow-through characteristic parameters, coupling calculation of supercharger overall efficiency, and performance evaluation of benchmark design threshold value; the application constructs a complete evaluation system covering two modules of compressor characteristics and turbine flow-through characteristics, obtains five core indexes of actual control rotating speed, total pressure ratio, efficiency, converted flow and unit mass power consumption of the compressor side through boundary input parameters, simultaneously obtains three key parameters of similar rotating speed, similar flow and expansion ratio of the turbine side, and finally coupling calculates the overall efficiency of the supercharger, realizes the full-dimension quantitative checking of the compressor and the turbine for the first time, and makes the evaluation of key indexes such as pressure ratio, flow, efficiency and the like have a basis.

Description

Technical Field

[0001] This invention relates to the field of new energy internal combustion engine technology, and in particular to a calculation formula and evaluation method for the characteristic test of a turbocharger for internal combustion engines. Background Technology

[0002] In response to increasingly severe environmental pollution and global warming, various regions have accelerated the formulation and implementation of emission regulations. With new emission standards about to be implemented, the development time left for OEMs is quite tight. These standards require simultaneous measurement of fuel consumption and CO2 emissions. As a crucial component of new energy range extenders, the performance of the internal combustion engine directly impacts the efficiency of these extenders. With the widespread application of turbocharging technology in range extender internal combustion engines, the matching accuracy between the turbocharger and the engine has become crucial in determining the overall engine's power, economy, and emissions levels. However, in actual development, existing technologies lack systematic and complete calculation formulas and evaluation methods for turbocharger characteristics specifically designed for internal combustion engines. This makes it impossible to achieve precise matching and characteristic verification of key components such as the turbocharger compressor and turbine with the engine under all operating conditions. Consequently, key indicators such as the turbocharger's pressure ratio, flow rate, and efficiency deviate significantly from the engine's actual requirements, leading to problems such as delayed engine power response, high fuel consumption, worsened emissions, and even turbocharger overspeeding and surge. These deviations not only severely delay project development cycles and plans but also cause unnecessary waste of resources. Therefore, this invention proposes a calculation formula and evaluation method for turbocharger characteristics specifically designed for internal combustion engines to address the problems existing in the prior art. Summary of the Invention

[0003] To address the aforementioned issues, this invention proposes a calculation formula and evaluation method for the characteristics of a turbocharger specifically designed for internal combustion engines. It constructs a complete evaluation system covering two major modules: compressor characteristics and turbine flow characteristics. By using boundary input parameters, it obtains five core indicators on the compressor side: actual control speed, total pressure ratio, efficiency, converted flow rate, and power consumption per unit mass. Simultaneously, it obtains three key parameters on the turbine side: similar speed, similar flow rate, and expansion ratio. Finally, it couples and calculates the overall efficiency of the turbocharger. This system fills the gap in existing technologies for a systematic turbocharger characteristic evaluation scheme, achieving for the first time a comprehensive quantitative verification of the compressor and turbine. This provides a reliable basis for evaluating key indicators such as pressure ratio, flow rate, and efficiency, effectively avoiding problems such as delayed engine power response, high fuel consumption, and worsened emissions caused by the lack of evaluation methods.

[0004] To achieve the objectives of this invention, the following technical solution is provided: a calculation formula and evaluation method for the characteristic test of a turbocharger specifically for internal combustion engines. The turbocharger in the adapted internal combustion engine includes a compressor end and a turbine end, wherein the compressor end and the turbine end are coaxially connected via a turbocharger shaft. The method executes sequentially according to the following logic: basic parameter input, calculation of compressor thermodynamic characteristic parameters, calculation of turbine flow characteristic parameters, coupled calculation of overall turbocharger efficiency, and performance evaluation by benchmarking against design thresholds. Specifically, it includes the following steps: S1: Obtain standard atmospheric temperature, standard atmospheric pressure, and the conversion constant between the Celsius and Kelvin temperature scales; S2: Obtain the measured operating parameters at the compressor end and calculate the five core indicators of compressor characteristics, including actual control speed, compressor total pressure ratio, compressor efficiency, compressor converted flow rate and compressor unit mass power consumption; when all five indicators meet their respective design thresholds, the compressor characteristics are deemed qualified. S3: Obtain the measured operating parameters at the turbine end, calculate the turbine flow characteristic parameters, including turbine similar speed, turbine similar flow rate and turbine expansion ratio; evaluate in combination with characteristic curves, and transfer the turbine expansion ratio to the overall efficiency calculation after passing the evaluation. S4: Based on the compressor end parameters and turbine end parameters, calculate the total efficiency of the turbocharger and compare it with the target efficiency threshold: if the total efficiency of the turbocharger is not less than the target value, it is determined that the turbocharger and engine are reasonably matched; if the total efficiency of the turbocharger is less than the target value, rectification is carried out until the target is met.

[0005] A further improvement lies in the following: In S2, the calculation method for the five core indicators is as follows: S2.1. Obtain the actual control speed for the turbocharger characteristic test using equation (1): ; In equation (1), n ​​is the rated design theoretical speed of the turbocharger. The total temperature at the compressor inlet is C, where C is the conversion constant between the Celsius and Kelvin scales. Standard atmospheric temperature; actual control speed Used to compare experimental data with the compressor's general characteristic curve, i.e., the MAP plot, when When the operating speed deviates from the design speed, pay attention to whether the operating point enters the surge or blockage zone; S2.2. Obtain the total pressure ratio R of the compressor using equation (2). c : ; In equation (2), P * c2 P is the total pressure at the compressor outlet. * c1The total pressure at the compressor inlet is P0, and the ambient atmospheric pressure is R; the total pressure ratio is R. c That is, the compressor pressure ratio πc, which serves as the core independent variable for subsequent efficiency and power consumption calculations; S2.3. Obtain the compressor efficiency using equation (3). : ; In equation (3), Here, πc represents the total temperature at the compressor outlet, k is the adiabatic index, and πc is the total pressure ratio of the compressor; πc determines the theoretical value of the isentropic compression temperature rise. S2.4. Obtain the converted flow rate of the compressor using equation (4). : ; In equation (4), For actual measured flow rate; convert flow rate Independent of other formulas, but with the actual control speed of equation (1) Pairing is used to locate the operating point on the compressor MAP, thereby determining whether it has entered the surge or blockage zone; S2.5. Obtain the compressor's power consumption per unit mass using equation (5). : ; In equation (5), R is the air gas constant. The isentropic efficiency of the compressor is compared with the compressor efficiency calculated by equation (3). Equivalent in a physical sense, that is Power consumption per unit mass It is a key output on the compressor side and will be transmitted to S4 for calculating the overall efficiency of the turbocharger.

[0006] A further improvement is that S2 also includes an evaluation step: the above five indicators, namely the actual controlled rotational speed. Total pressure ratio R c ,efficiency Calculate the flow rate and power consumption per unit mass Only when all design thresholds are met can the compressor characteristics be deemed qualified, and then proceed to S3 and S4 for turbine and overall efficiency evaluation; if any indicator fails to meet the threshold, the process should be repeated after adjusting the turbocharger selection or operating parameters.

[0007] A further improvement is made in the following: In S3, the calculation method for the turbine flow characteristic parameters is as follows: S3.1. Obtain the measured theoretical rotational speed using equation (6). : ; In equation (6), T represents the measured turbine speed. t The temperature at the turbine inlet; S3.2 Obtain turbine-like flow rate using equation (7) : ; In equation (7), The measured or calculated turbine mass flow rate The total temperature at the turbine inlet. The total pressure at the turbine inlet; S3.3, Obtain the turbine expansion ratio R using equation (8) t : ; In equation (8), P t1 P is the total pressure at the turbine inlet. t2 P0 is the static pressure at the turbine outlet and P0 is the ambient atmospheric pressure.

[0008] A further improvement is that S3 also includes an evaluation step based on characteristic curves: using the calculation results of equations (6), (7), and (8) combined with the turbine characteristic curve, i.e., the MAP diagram, for evaluation: when If the deviation from the design value is large, the speed measurement or inlet temperature sensor needs to be corrected; when the turbine similar flow rate... With the turbine expansion ratio R t If the combined operating point deviates from the characteristic curve, it is determined that the turbine flow capacity has decreased or the bypass valve is malfunctioning; after passing the evaluation, the turbine expansion ratio R is adjusted. t Substitute into S4 to calculate the overall efficiency of the turbocharger. .

[0009] A further improvement lies in: in S4, the overall efficiency of the turbocharger... The calculation formula is: ; In equation (9), 0.888 is the empirical coefficient of compressor mechanical efficiency, K1 is the compressor adiabatic index, K2 is the turbine adiabatic index, and π c π is the overall compressor pressure ratio. t This is the total pressure expansion ratio of the turbine. This refers to the total temperature at the compressor inlet. The total temperature at the turbine inlet is C, which is a conversion constant. The numerator represents the theoretical temperature rise required for isentropic compression of the compressor, and the denominator represents the theoretical temperature drop that isentropic expansion of the turbine can provide. The ratio of the two reflects the energy transfer efficiency of the entire turbocharger.

[0010] A further improvement is made in S4, where the performance evaluation and determination method is as follows: Overall efficiency of turbocharger satisfy in ,target is the target efficiency value, which is determined by the engine development target and is taken as 0.55~0.65; when The calculated value is greater than or equal to the target efficiency value: the turbocharger is well matched with the engine and can be directly used in the development of the whole machine; when Calculated value is less than target value: Check compressor efficiency. And the turbine expansion ratio π t The modifications were made by replacing the turbine housing, adjusting the exhaust bypass valve opening strategy, or optimizing the compressor impeller profile until the problem was resolved. Meets the standard.

[0011] Further improvements are made in the following structural connections of the turbocharger: the intermediate body supports the turbocharger shaft via floating bearings, thus connecting the compressor end and turbine end as one unit; the compressor volute cooperates with the bladeless diffuser to collect and pressurize air; the turbine housing guides the exhaust gas from the engine body to drive the turbine impeller and drive the compressor impeller to rotate synchronously; the oil inlet supplies lubricating oil to the bearing system, and the oil outlet cooperates with the return oil line to achieve lubrication and cooling; the engine body is connected to the compressor end through the air intake and delivers exhaust gas to the turbine end through the exhaust inlet; the intercooler port connects to the intercooler to reduce the temperature of the pressurized air; and the exhaust bypass valve is used to regulate the turbine speed and boost pressure.

[0012] An electronic device includes a memory and a processor, the memory being used to store a program that supports the processor in executing the aforementioned calculation formula and evaluation method for a turbocharger characteristic test for an internal combustion engine, the processor being configured to execute the program stored in the memory.

[0013] A computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the aforementioned calculation formula and evaluation method for the characteristics test of a turbocharger for internal combustion engines.

[0014] The beneficial effects of this invention are as follows: 1. This invention constructs a complete evaluation system covering two major modules: compressor characteristics and turbine flow characteristics. By using boundary input parameters, it obtains five core indicators on the compressor side: actual control speed, total pressure ratio, efficiency, converted flow rate, and power consumption per unit mass. At the same time, it obtains three key parameters on the turbine side: similar speed, similar flow rate, and expansion ratio. Finally, it couples and calculates the overall efficiency of the turbocharger. This system fills the gap in the existing technology of lacking a systematic turbocharger characteristic evaluation scheme. For the first time, it realizes the quantitative verification of the compressor and turbine in all dimensions, making the evaluation of key indicators such as pressure ratio, flow rate, and efficiency based on evidence. It effectively avoids problems such as lagging overall power response, high fuel consumption, and deteriorating emissions caused by the lack of evaluation methods.

[0015] 2. The calculation parameters and theories used in this invention are all commonly used basic design methods for the key characteristics of turbochargers in the design of internal combustion engine intake efficiency matching. The results obtained are more in line with the engineering reality of improving the performance of internal combustion engines. A complete parameter transfer chain is formed between the various formulas: the compressor total pressure ratio is used as the core independent variable to drive the efficiency and power consumption calculation, the power consumption per unit mass is transferred to the total efficiency formula, and the turbine expansion ratio is also incorporated into the total efficiency coupling calculation. Each link is closely connected, ensuring the physical consistency and engineering credibility of the evaluation results, and has strong engineering applicability.

[0016] 3. The dedicated turbocharger characteristic test calculation method of the present invention is applicable to the basic structure of new energy and industrial internal combustion engines, that is, a structure with multiple turbochargers. According to different internal combustion engines and equipment requirements, the key parameters and target parameters can be adjusted accordingly. The theoretical calculation method has strong versatility and scalability, and can meet the evaluation needs under differentiated combustion matching scenarios.

[0017] 4. After determining that the above-mentioned characteristic values ​​are within a reasonable design range through theoretical calculations, this invention can provide a theoretical basis for theoretical research and technical feasibility assessment of matching different combustion performances of internal combustion engines. This method uses key performance indicators of internal combustion engines to extract the input parameters required for calculation and can compare the theoretical calculation results with the design indicators to evaluate the feasibility of the design scheme. It provides an effective means for theoretical calculation and conclusion assessment of the combustion intake efficiency of internal combustion engines. When the total efficiency of the turbocharger does not meet the standard, the compressor efficiency or turbine expansion ratio can be investigated in a targeted manner, and targeted rectification can be carried out by replacing the turbine housing, adjusting the opening strategy of the exhaust bypass valve, or optimizing the compressor impeller profile. It provides a quantitative tool for simulation calculation and scheme verification of engine intake and combustion efficiency, and its practicality in engineering implementation is outstanding. Attached Figure Description

[0018] Figure 1 This is a flowchart of the present invention; Figure 2 This is a schematic diagram of the basic structural components of the internal combustion engine turbocharger of the present invention; Figure 3 This is a schematic diagram of the key components of the turbocharger of the present invention in an internal combustion engine.

[0019] The components are: 1. Compressor volute; 2. Bladeless diffuser; 3. Compressor impeller; 4. Sealing sleeve; 5. Turbocharger shaft; 6. Intake duct; 7. Impeller fixing bolts; 8. Air inlet; 9. Thrust bearing; 10. Oil baffle; 11. Intermediate body; 12. Oil inlet; 13. Turbine housing; 14. Heat insulation plate; 15. Exhaust outlet; 16. Exhaust duct; 17. Turbine impeller; 18. Floating bearing; 19. Oil outlet; 20. Oil return line; 21. Engine body; 22. Exhaust inlet; 23. Intercooler port; 24. Exhaust outlet; 25. Waste gas bypass valve; 26. Intake port. Detailed Implementation

[0020] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention. Example 1

[0021] according to Figure 1 , 2 As shown in Figure 3, this embodiment proposes a calculation formula and evaluation method for the characteristic test of a turbocharger for internal combustion engines. The turbocharger in the internal combustion engine includes: a compressor volute, a bladeless diffuser, a compressor impeller, a turbocharger shaft, an intermediate body, an oil inlet, a turbine housing, a turbine impeller, a floating bearing, an oil outlet, an oil return line, an engine body, an exhaust inlet, an intercooler port, a waste gas bypass valve, and an intake port. The intermediate body supports the turbocharger shaft via a floating bearing, thereby connecting the compressor end and the turbine end as a single unit. The compressor volute cooperates with the bladeless diffuser to collect and pressurize air. The turbine housing guides the exhaust gas from the engine body to drive the turbine impeller and, in turn, the compressor. The impeller rotates synchronously; the oil inlet supplies lubricating oil to the bearing system, and the oil outlet cooperates with the return oil line to achieve lubrication and cooling; the engine body is connected to the compressor end through the air inlet and delivers exhaust gas to the turbine end through the exhaust inlet; the intercooler is connected to the intercooler to reduce the temperature of the air after boosting; the exhaust bypass valve is used to regulate the turbine speed and boost pressure; this method is a step-by-step calculation and evaluation method for the characteristics of internal combustion engine turbochargers. The overall logic is: input of basic test / design parameters → parallel calculation of compressor thermodynamic characteristic parameters + turbine flow characteristic parameters in two paths → coupled calculation of the overall efficiency of the turbocharger → benchmark against the design threshold to complete the performance evaluation, realizing the full-dimensional quantitative verification of the turbocharger compressor and turbine. The evaluation method includes the following steps: S1: Obtain standard atmospheric temperature T 标准 Standard atmospheric pressure P 标准 The conversion constant C between the Celsius and Kelvin temperature scales; S2: Obtain the rated design theoretical speed n of the turbocharger and the total inlet temperature T of the compressor. * c1 The total pressure P at the compressor outlet * c2 Total pressure P at the compressor inlet * c1 Ambient atmospheric pressure P0, total temperature at compressor outlet T * c2 The total pressure ratio π of the compressor c Adiabatic index K, actual measured flow rate G c The air gas constant R; thus, the pressure ratio characteristic parameters and efficiency characteristic parameters of the compressor are calculated, including the actual control speed. The total pressure ratio R of the compressor c The efficiency η of the compressor c Compressor flow rate The unit mass power consumption (W) of the compressor C ; S2.1. Obtain the actual control speed for the turbocharger characteristic test using equation (1). : ; S2.2. Obtain the total pressure ratio R of the compressor in the turbocharger using equation (2). c ; ; S2.3. Obtain the compressor efficiency η in the turbocharger using equation (3). c ; ; S2.4. Obtain the flow rate of the compressor in the turbocharger using equation (4). ;

[0022] S2.5. Obtain the compressor's unit mass power consumption W using equation (5). C ; ; In equation (5), This represents the isentropic efficiency of the compressor.

[0023] S2.6 The evaluation relationship is that the compressor characteristics can only be deemed qualified when all five indicators meet their respective thresholds, and only then can it proceed to S3 and S4 for turbine and overall efficiency evaluation. Among them, equations (1) to (4) and equation (3) are: The actual control speed calculated by equation (1) It is not a direct input to subsequent formulas, but rather used to compare experimental data with the compressor's universal characteristic curve (MAP plot); when When the speed deviates from the design speed, the temperature and pressure conversion bases in equations (3) and (4) need to be revised. Among them, equations (2), (3), and (5): The total pressure ratio Rc obtained from equation (2) is the compressor pressure ratio. It is the core independent variable in equations (3) and (5); In equation (3), This determines the theoretical value of the temperature rise during isentropic compression.

[0024] In equation (5), Directly affects power consumption per unit mass; Among them, equations (3) and (5) are: Formula (3) is used to calculate the compressor efficiency. The isentropic efficiency in equation (5) and They are physically equivalent (both are compressor adiabatic efficiencies). Therefore, equation (5) can actually be calculated using the result of equation (3), i.e. ; Among them, equation (4) is independent: Equation (4) is used to calculate the equivalent flow rate. It is independent of other formulas, but requires the converted rotational speed of formula (1). Pairing is used to locate the operating point on the compressor MAP, thereby determining whether it has entered the surge or blockage zone; The final output of equation (5) is: Power consumption per unit mass It is the key output on the compressor side, which will be passed to equation (9) of S4, and together with the turbine side parameters, the overall turbocharger efficiency will be calculated. .

[0025] S3: Obtain the measured turbine speed n T Turbo inlet temperature T t Measured or converted turbine mass flow rate G T Total temperature T at turbine inlet T1 Total pressure P at turbine inlet T1 Total pressure P at turbine inlet t1 The static pressure P at the turbine outlet t2 Compressor adiabatic index K1, turbine adiabatic index K2, turbine total pressure expansion ratio π t Total temperature T at turbine inlet * t1 This allows for the calculation of turbine flow characteristic parameters, including: theoretical rotational speed n, turbine similar flow rate G. MTurbine expansion ratio R t In this context, "c" in the subscript represents the compressor, "t" represents the turbine, "1" represents the inlet, and "2" represents the outlet. S3.1. Obtain the measured theoretical rotational speed using equation (6). ; ; S3.2. Obtain the turbine-like flow rate G using equation (7). M ; ; S3.2. Obtain the turbine expansion ratio R using equation (8). t ; ; S3.3. Evaluate using equations (6), (7), and (8) in conjunction with characteristic curves (MAP plots); like If the deviation from the design value is large, the speed measurement or inlet temperature sensor needs to be corrected. like( and R t If the point deviates from the curve, it can be determined that the turbine's flow capacity has decreased (such as due to carbon buildup) or the bypass valve is malfunctioning. Qualified R t Substituting into equation (9) of S4, we can calculate the overall efficiency of the turbocharger. .

[0026] S4: Calculate the total efficiency η of the turbocharger using equation (9) tc ; ; Based on the aforementioned method for evaluating the characteristics of turbochargers specifically designed for internal combustion engines, after acquiring and calculating parameters S1, S2, and S3, the overall efficiency of the turbocharger is... Should meet ,target (target), where η tc The target is determined by the engine development goals (usually in the range of 0.55 to 0.65). like The calculated value is greater than the target value: the turbocharger is well matched with the engine and can be directly used in the development of the whole machine; like If the calculated value is less than the target value, the compressor efficiency needs to be checked. and turbine expansion ratio The modifications were made by replacing the turbine housing, adjusting the exhaust bypass valve opening strategy, or optimizing the compressor impeller profile until the problem was resolved. Meets the standard. Example 2

[0027] according to Figure 1 , 2 As shown in Figure 3, this embodiment proposes a calculation formula and evaluation method for the characteristics of a turbocharger specifically for internal combustion engines. Based on technical standards or design requirements, the characteristics of the turbocharger compressor are obtained through hardware design, simulation, and experimental calculations. These include the basic parameters of the compressor volute 1, the channel of the bladeless diffuser 2, the compressor impeller 3, the sealing sleeve 4, the turbocharger shaft 5, the intake duct 6, the impeller fixing bolts 7, and the air inlet. In the energy transfer chain, the high-temperature exhaust gas from the engine is introduced through the turbine housing 13, driving the turbine impeller 17 to rotate at high speed. The turbine impeller and the compressor impeller 3 are rigidly connected through the turbocharger shaft 5, forming a coaxial rotating system that converts exhaust energy into mechanical energy, driving the compressor end to work synchronously. In the air compression process, fresh air enters the intake duct 6 through the air inlet 8 and is drawn in by the high-speed rotating compressor impeller 3, gaining kinetic energy. Subsequently, the airflow enters the bladeless diffuser 2, where changes in the channel cross-section reduce the flow velocity and increase the pressure. Finally, the high-pressure air is collected and discharged by the compressor volute 1, completing the turbocharging process. In the lubrication and cooling system, lubricating oil enters the intermediate body 11 through the oil inlet 12, forming an oil film lubrication for the floating bearing 18 and the thrust bearing 9, while simultaneously carrying away frictional heat and high temperatures conducted from the turbine end. The oil ultimately flows out through the oil outlet 19 and returns to the engine oil pan via the return oil line 20, forming a complete lubrication and cooling cycle. The sealing and heat insulation protective sleeve 4 isolates the lubrication oil passages between the compressor end and the intermediate body, preventing oil from entering the intake system. The heat insulation plate 14 is installed between the turbine housing 13 and the intermediate body 11, blocking the transmission of high-temperature exhaust gas to the bearing cavity and protecting the bearing and lubricating oil performance.

[0028] In this embodiment, a calculation formula and evaluation method for the characteristic test of a turbocharger for internal combustion engines is applied to an internal combustion engine and includes: a compressor volute 1, a bladeless diffuser 1, a compressor impeller 3, a sealing sleeve 4, a turbocharger shaft 5, an intake duct 6, an impeller fixing bolt 7, an air inlet 8, a thrust bearing 9, an oil baffle 10, an intermediate body 11, and an oil inlet 12 in the turbocharger's compression section; the turbine section mainly includes an oil inlet 12, a turbine housing 13, a heat shield 14, an exhaust outlet 15, an exhaust duct 16, a turbine impeller 17, a floating bearing 18, an oil outlet 19, an oil return line 20, an intercooler port 23, an exhaust outlet 24, and an intake port 26; the turbocharger assembly is connected and fixed through the engine body 21 and the exhaust inlet 22. In high-altitude conditions, to prevent the turbocharger from overspeeding, exhaust gas is released through a bypass valve 25 to reduce the speed.

[0029] The calculation formula and evaluation method for the characteristic test of the internal combustion engine turbocharger establishes a complete evaluation system covering two major modules: compressor characteristics and turbine flow characteristics. By using boundary input parameters, it obtains five core indicators on the compressor side: actual control speed, total pressure ratio, efficiency, converted flow rate, and power consumption per unit mass. At the same time, it obtains three key parameters on the turbine side: similar speed, similar flow rate, and expansion ratio. Finally, it couples and calculates the overall efficiency of the turbocharger. This system fills the gap in the existing technology of lacking a systematic turbocharger characteristic evaluation scheme. For the first time, it realizes the quantitative verification of the compressor and turbine in all dimensions, making the evaluation of key indicators such as pressure ratio, flow rate, and efficiency based on evidence. It effectively avoids problems such as lag in overall engine power response, high fuel consumption, and deterioration in emissions caused by the lack of evaluation methods. The calculation parameters and theories used in this invention are commonly used methods in the basic design of turbocharger key characteristics in the intake efficiency matching design of internal combustion engines. The results obtained are more in line with the engineering reality of improving internal combustion engine performance. A complete parameter transfer chain is formed between the various formulas: the compressor total pressure ratio serves as the core independent variable driving efficiency and power consumption calculations; power consumption per unit mass is transferred to the total efficiency formula; and the turbine expansion ratio is also incorporated into the total efficiency coupling calculation. Each link is interconnected, ensuring the physical consistency and engineering credibility of the evaluation results, and exhibiting strong engineering applicability. The dedicated turbocharger characteristic test calculation method of this invention is applicable to the basic structure of new energy and industrial internal combustion engines, i.e., a structure with multiple turbocharger components. According to different internal combustion engines and equipment requirements, the key parameters and target parameters can be adjusted accordingly. This theoretical calculation method has strong versatility and scalability, and can meet the evaluation needs under differentiated combustion matching scenarios. This invention, after determining through theoretical calculation that the aforementioned characteristic values ​​are within a reasonable design range, can provide a theoretical basis for theoretical research and technical feasibility assessment of matching different combustion performances of internal combustion engines. This method uses key performance indicators of internal combustion engines to extract the input parameters required for calculation and can compare the theoretical calculation results with design indicators to evaluate the feasibility of the design scheme. It provides an effective means for theoretical calculation and conclusion assessment of the combustion intake efficiency of internal combustion engines. When the total efficiency of the turbocharger is not up to standard, the compressor efficiency or turbine expansion ratio can be investigated in a targeted manner, and targeted rectification can be carried out by replacing the turbine housing, adjusting the opening strategy of the exhaust bypass valve, or optimizing the compressor impeller profile. It provides a quantitative tool for simulation calculation and scheme verification of engine intake and combustion efficiency, and its practicality in engineering implementation is outstanding.

[0030] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A calculation formula and evaluation method for the characteristic test of a turbocharger specifically for internal combustion engines, wherein the turbocharger in the adapted internal combustion engine includes a compressor end and a turbine end, wherein the compressor end and the turbine end are coaxially connected via a turbocharger shaft; characterized in that, This method executes sequentially according to the following logic: basic parameter input, compressor thermodynamic characteristic parameter calculation, turbine flow characteristic parameter calculation, turbocharger overall efficiency coupling calculation, and performance evaluation by benchmarking design thresholds; specifically, it includes the following steps: S1: Obtain standard atmospheric temperature, standard atmospheric pressure, and the conversion constant between the Celsius and Kelvin temperature scales; S2: Obtain the measured operating parameters at the compressor end and calculate the five core indicators of compressor characteristics, including actual control speed, compressor total pressure ratio, compressor efficiency, compressor converted flow rate and compressor unit mass power consumption; when all five indicators meet their respective design thresholds, the compressor characteristics are deemed qualified. S3: Obtain the measured operating parameters at the turbine end, calculate the turbine flow characteristic parameters, including turbine similar speed, turbine similar flow rate and turbine expansion ratio; evaluate in combination with characteristic curves, and transfer the turbine expansion ratio to the overall efficiency calculation after passing the evaluation. S4: Based on the compressor end parameters and turbine end parameters, calculate the total efficiency of the turbocharger and compare it with the target efficiency threshold: if the total efficiency of the turbocharger is not less than the target value, it is determined that the turbocharger and engine are reasonably matched; if the total efficiency of the turbocharger is less than the target value, rectification is carried out until the target is met.

2. The calculation formula and evaluation method for the characteristic test of a turbocharger for internal combustion engines according to claim 1, characterized in that: In S2, the calculation methods for the five core indicators are as follows: S2.

1. Obtain the actual control speed for the turbocharger characteristic test using equation (1): ； In equation (1), n ​​is the rated design theoretical speed of the turbocharger. The total temperature at the compressor inlet is C, where C is the conversion constant between the Celsius and Kelvin scales. Standard atmospheric temperature; actual control speed Used to compare experimental data with the compressor's general characteristic curve, i.e., the MAP plot, when When the operating speed deviates from the design speed, pay attention to whether the operating point enters the surge or blockage zone; S2.

2. Obtain the total pressure ratio R of the compressor using equation (2). c : ； In equation (2), P * c2 P is the total pressure at the compressor outlet. * c1 The total pressure at the compressor inlet is P0, and the ambient atmospheric pressure is R; the total pressure ratio is R. c That is, the compressor pressure ratio πc, which serves as the core independent variable for subsequent efficiency and power consumption calculations; S2.

3. Obtain the compressor efficiency using equation (3). : ； In equation (3), Here, πc represents the total temperature at the compressor outlet, k is the adiabatic index, and πc is the total pressure ratio of the compressor; πc determines the theoretical value of the isentropic compression temperature rise. S2.

4. Obtain the converted flow rate of the compressor using equation (4). : ； In equation (4), For actual measured flow rate; convert flow rate Independent of other formulas, but with the actual control speed of equation (1) Pairing is used to locate the operating point on the compressor MAP, thereby determining whether it has entered the surge or blockage zone; S2.

5. Obtain the compressor's power consumption per unit mass using equation (5). : ； In equation (5), R is the air gas constant. The isentropic efficiency of the compressor is compared with the compressor efficiency calculated by equation (3). Equivalent in a physical sense, that is Power consumption per unit mass It is a key output on the compressor side and will be transmitted to S4 for calculating the overall efficiency of the turbocharger.

3. The formula and evaluation method for testing the characteristics of a turbocharger for internal combustion engines according to claim 2, characterized in that: The S2 also includes an evaluation step: the above five indicators are the actual controlled rotational speed. Total pressure ratio R c ,efficiency Calculate the flow rate and power consumption per unit mass Only when all design thresholds are met can the compressor characteristics be deemed qualified, and then proceed to S3 and S4 for turbine and overall efficiency evaluation; if any indicator fails to meet the threshold, the process should be repeated after adjusting the turbocharger selection or operating parameters.

4. The calculation formula and evaluation method for the characteristic test of a turbocharger for internal combustion engines according to claim 1, characterized in that: In S3, the turbine flow characteristic parameters are calculated as follows: S3.

1. Obtain the measured theoretical rotational speed using equation (6). : ； In equation (6), T represents the measured turbine speed. t The temperature at the turbine inlet; S3.2 Obtain turbine-like flow rate using equation (7) : ； In equation (7), The measured or calculated turbine mass flow rate The total temperature at the turbine inlet. The total pressure at the turbine inlet; S3.3, Obtain the turbine expansion ratio R using equation (8) t : ； In equation (8), P t1 P is the total pressure at the turbine inlet. t2 P0 is the static pressure at the turbine outlet and P0 is the ambient atmospheric pressure.

5. The calculation formula and evaluation method for the characteristic test of a turbocharger for internal combustion engines according to claim 4, characterized in that: The S3 also includes an evaluation step based on characteristic curves: evaluation is performed using the calculation results of equations (6), (7), and (8) combined with the turbine characteristic curve, i.e., the MAP diagram: when If the deviation from the design value is large, the speed measurement or inlet temperature sensor needs to be corrected; when the turbine similar flow rate... With the turbine expansion ratio R t If the combined operating point deviates from the characteristic curve, it is determined that the turbine flow capacity has decreased or the bypass valve is malfunctioning; after passing the evaluation, the turbine expansion ratio R is adjusted. t Substitute into S4 to calculate the overall efficiency of the turbocharger. .

6. The calculation formula and evaluation method for the characteristic test of a turbocharger for internal combustion engines according to claim 1, characterized in that: In S4, the overall efficiency of the turbocharger The calculation formula is: ； In equation (9), 0.888 is the empirical coefficient of compressor mechanical efficiency, K1 is the compressor adiabatic index, K2 is the turbine adiabatic index, and π c π is the overall compressor pressure ratio. t The total pressure expansion ratio of the turbine. This refers to the total temperature at the compressor inlet. The total temperature at the turbine inlet is C, which is a conversion constant. The numerator represents the theoretical temperature rise required for isentropic compression of the compressor, and the denominator represents the theoretical temperature drop that isentropic expansion of the turbine can provide. The ratio of the two reflects the energy transfer efficiency of the entire turbocharger.

7. The formula and evaluation method for testing the characteristics of a turbocharger for internal combustion engines according to claim 6, characterized in that: In S4, the performance evaluation and determination method is as follows: Overall efficiency of turbocharger satisfy in ,target is the target efficiency value, which is determined by the engine development target and is taken as 0.55~0.65; when The calculated value is greater than or equal to the target efficiency value: the turbocharger is well matched with the engine and can be directly used in the development of the whole machine; when Calculated value is less than target value: Check compressor efficiency. And the turbine expansion ratio π t The modifications were made by replacing the turbine housing, adjusting the exhaust bypass valve opening strategy, or optimizing the compressor impeller profile until the problem was resolved. Meets the standard.

8. The formula and evaluation method for the characteristic test of a turbocharger for internal combustion engines according to claim 1, characterized in that: The turbocharger's structural connections are as follows: the intermediate body supports the turbocharger shaft via floating bearings, thus connecting the compressor end and turbine end as one unit; the compressor volute cooperates with the bladeless diffuser to collect and pressurize air; the turbine housing guides the engine exhaust to drive the turbine impeller and drives the compressor impeller to rotate synchronously; the oil inlet supplies lubricating oil to the bearing system, and the oil outlet cooperates with the return oil line to achieve lubrication and cooling; the engine body is connected to the compressor end through the air intake and delivers exhaust gas to the turbine end through the exhaust inlet; the intercooler port connects to the intercooler to reduce the temperature of the pressurized air; and the exhaust bypass valve is used to regulate the turbine speed and boost pressure.

9. An electronic device, comprising a memory and a processor, characterized in that: The memory is used to store a program that supports the processor in executing a calculation formula and evaluation method for the characteristic test of a turbocharger for internal combustion engines according to any one of claims 1-8, and the processor is configured to execute the program stored in the memory.

10. A computer-readable storage medium storing a computer program thereon, characterized in that: When the computer program is run by the processor, it executes the steps of the calculation formula and evaluation method for the characteristic test of a turbocharger for internal combustion engines as described in any one of claims 1-8.

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