A quantitative estimation method for the power enhancement potential of air-cooled machines

Abstract

The present invention discloses a method for quantitatively estimating the power enhancement potential of an air-cooled machine, which belongs to the technical field of engine power estimation. The method for quantitatively estimating the power enhancement potential of an air-cooled machine includes: obtaining the performance parameters of the air-cooled machine, the reverse cylinder pressure curve in the hot engine state, and the heat release rate curve; establishing a one-dimensional simulation model of the air-cooled machine to obtain the gas state parameters of the air-cooled machine's thermal cycle; establishing a three-dimensional combustion simulation model to calculate the thermodynamic state of the gas in the combustion chamber during the compression stage after the intake valve is closed; establishing a three-dimensional structural simulation model of the cylinder components of the air-cooled machine; using the three-dimensional combustion simulation model to optimize the oil and gas chamber, and verifying the thermal-mechanical load of each component to obtain the optimized heat release rate; inputting the optimized heat release rate into the one-dimensional simulation model to quantitatively calculate the power enhancement potential of the air-cooled machine. Using the method for quantitatively estimating the power enhancement potential of an air-cooled machine described in the present invention, digital simulation technology is used to quantitatively estimate the power enhancement potential of an air-cooled machine, thereby improving the efficiency of enhancement design.

Description

Technical Field

[0001] The present invention relates to the technical field of engine power estimation, and in particular to a method for quantitatively estimating the power enhancement potential of an air-cooled machine. Background Art

[0002] Diesel engines can be divided into air-cooled and water-cooled engines based on their cooling method. Air-cooled engines are widely used in water-scarce and high-temperature environments. Limited by the cooling capacity of air cooling, air-cooled engines have low heat dissipation capabilities. Therefore, the power design ceiling of most existing models is lower than that of water-cooled engines, and relatively little research has been conducted on power enhancement of air-cooled engines. With increasing productivity demands, further power enhancement of air-cooled engines is necessary. With the optimization of cooling structure design and the development of high-temperature alloy material research, air-cooled engines can withstand higher mechanical and thermal loads, gradually meeting the conditions for further power enhancement of air-cooled engines.

[0003] Before performing actual machine power enhancement, it is necessary to explore the potential for power enhancement. This can help determine whether the enhanced machine model has the potential for application in the corresponding scenario, provide data support for the enhancement process, and theoretically guide the enhancement of air-cooled machines. The current process of exploring the power enhancement potential of air-cooled machines relies on orthogonal experiments and an exhaustive approach. This related work mainly relies on actual machine testing, which is time-consuming.

[0004] Water-cooled machines have a coolant circulation system, making it easy to measure and calculate their cooling capacity. The cooling process simply requires ensuring that the coolant temperature does not exceed a certain threshold. However, the heat load of an air-cooled machine's cooling system is difficult to measure. During engineering tests to increase the power of an air-cooled machine, there is a practice of directly increasing the fuel injection rate to test the power ceiling. Since cooling requirements are difficult to measure, there is no guarantee that the cooling system will meet the cooling requirements after the increase, which can easily damage the test air-cooled machine due to excessive thermal-mechanical loads on components. Summary of the Invention

[0005] The present invention aims to provide a method for quantitatively estimating the power enhancement potential of air-cooled machines, using digital simulation technology to quantitatively estimate the power enhancement potential of air-cooled machines and improve the efficiency of enhancement design. By integrating thermal-mechanical load calculations and verification into the power enhancement estimation, the enhancement design process verifies that the enhancement process is within the permitted cooling capacity. This avoids discrepancies between the estimated enhancement potential and the actual operating conditions, reduces the risk of damage to the air-cooled machine during the enhancement design verification phase, mitigates economic losses, and avoids safety hazards.

[0006] To achieve the above-mentioned objectives, the present invention provides a method for quantitatively estimating the power enhancement potential of an air-cooled machine. Before estimating the enhancement potential, it is first necessary to determine the air-cooled machine to be enhanced, whether power enhancement is allowed and whether its application scenario requires power enhancement. Allowable power enhancement means that the rated operating thermo-mechanical load of the target air-cooled machine has not reached the allowable upper limit or the heat flow distribution in the cylinder can be optimized to increase the power without increasing the thermo-mechanical load; or the material and structure are optimized to increase the upper limit of the thermo-mechanical load that constrains its power enhancement.

[0007] A quantitative estimation method for the power enhancement potential of an air-cooled machine includes the following steps:

[0008] S1. Obtain the performance parameters of the air-cooled machine and the reverse-drag cylinder pressure curve of the air-cooled machine in the hot state through bench testing; and obtain the preliminary heat release rate through thermodynamic analysis under the condition that the boundary parameters take empirical values.

[0009] The performance parameters of the air-cooled machine include the intake flow rate under stable working conditions and the cylinder pressure curve of the air-cooled machine.

[0010] The basic test equipment is a dynamometer, operating the air-cooled engine at a constant speed using speed control. The corresponding data acquisition equipment includes a cylinder pressure sensor, a combustion analyzer, and corresponding combustion analysis software. A flow meter is used to measure intake air flow during testing. The cylinder pressure sensor is used to collect the cylinder pressure curve for the air-cooled engine. Data is collected after the air-cooled engine has stabilized at the target operating conditions for three minutes. Multiple engine cycles are collected, and thermodynamic analysis is performed on each transient cycle. The combustion analysis software reads cylinder pressure, temperature, and heat release rate. However, results obtained based on simple empirical formulas are inaccurate and should only be used as a reference. Combustion simulation calculations require calculating the heat release rate curve based on multiple cylinder pressure cycles and taking the arithmetic average as the heat release rate for that condition. The combustion analyzer's combustion onset is a reliable parameter. Specifically, the combustion onset is the crankshaft angle at which the cumulative heat release exceeds 2% of the total fuel heat. The accuracy is generally 0.1 crankshaft degree.

[0011] According to the first law of thermodynamics, the heat release rate of the fuel in the cylinder is equal to the sum of the rate of change of the internal energy of the working fluid in the cylinder, the rate of heat transfer between the working fluid and the wall in the cylinder, and the rate of change of the work done by the working fluid. Specifically:

[0012] The heat release rate calculation formula is:

[0013] ;

[0014] in, ;

[0015] in, ;

[0016] in, .

[0017] in, represents the differential, Represents the heat released by combustion, represents the crankshaft angle, U Represents internal energy, L represents the heat transfer, represents the amount of work done; represents the fuel heat release rate, Represents the speed of change of internal energy of the working medium in the cylinder, Represents the heat transfer rate between the working medium in the cylinder and the wall, Represents the changing speed of the working fluid doing work; P is the measured cylinder pressure, V Represents the real-time cylinder volume, F Represents the heat dissipation area, K represents the polynomial index, represents the rotation speed; Represents the part number, i.e. cylinder head, cylinder liner, piston; represents the heat transfer coefficient, represents the gas temperature in the cylinder, Representative parts The wall temperature.

[0018] In the above formula, the heat release rate calculation process involves obtaining numerical values ​​for the wall temperature and the gas temperature. The gas temperature can be read using a combustion analyzer. Since air-cooled units generally have higher wall temperatures than water-cooled units, resulting in a softer combustion process, accurately determining the wall temperature can effectively improve combustion simulation accuracy. However, since it is difficult to measure, the wall temperature is iteratively determined using digital simulation after the model is established.

[0019] S2. Establish a one-dimensional simulation model of the air cooler based on the design parameters of the air cooler and the performance parameters in S1 to obtain the state parameters of the thermodynamic cycle gas of the air cooler.

[0020] The air-cooled machine is modeled into one-dimensional modular form using GT-POWER software, and the gas distribution system pipeline is preferably converted into a one-dimensional form using GEM3D software to scan the three-dimensional pipeline model.

[0021] The model parameters should be consistent with the target air-cooled engine. For air-cooled engines with a turbocharger, the turbocharger system MAP must be accurately input. The core calibration objective of the one-dimensional simulation model is to accurately calculate the air-cooled engine's valvetrain data and indicated power, ensuring that the heat release rate is consistent with the direct output of the combustion analyzer and that the simulated and measured intake flow rates are consistent. Generally, a discrepancy of less than 5% is required. For this purpose, empirical values ​​are used for wall temperatures, such as 600K for the piston and cylinder head walls and 500K for the cylinder liner wall.

[0022] S3. Based on the test results, a three-dimensional combustion simulation model is established to calculate the thermodynamic state parameters of the gas in the combustion chamber during the compression phase after the intake valve is closed. The model is then iterated with the one-dimensional simulation model to optimize the wall temperature.

[0023] The converge software is used to establish a three-dimensional combustion simulation model of the engine and perform a three-dimensional simulation of the compression stroke, in which the RNGk-ε model is used as the turbulence model.

[0024] The initial gas state is provided by the results of a one-dimensional simulation model. The compression stroke calibration is performed using the cylinder pressure curve of the air-cooled engine in the hot state to determine the engine wall temperature. The hot state refers to the air-cooled engine running steadily at this speed for three minutes, then stopping the fuel supply system and using the dynamometer to maintain the air-cooled engine speed.

[0025] The wall temperature is calculated using the compression curve. In the three-dimensional calculation, the error between the pressure and the measured value within the crank angle range of 10° before and after the start of combustion is less than 2%. Specific analysis: During the compression process, the heat transfer rate from the working fluid in the cylinder to the wall is negative, that is, the wall heats the gas. For the gas in the cylinder, the following conditions are met:

[0026] ;

[0027] The heat transfer rate between the working fluid and the cylinder wall is equal to the sum of the rate of change in the working fluid's internal energy and the rate of change in the work done by the piston on the working fluid. When the wall temperature is set high, the change in internal energy is greater than the actual change, the gas pressure and temperature in the cylinder increase, and the amount of work done by the piston on the working fluid increases. The cylinder pressure and temperature at the start of combustion are higher than the actual operating conditions, which affects the accuracy of the combustion simulation calculation results. Adjust the wall temperature so that the calculated pressure at the start of combustion in the three-dimensional combustion simulation model is equal to the measured pressure. Correspondingly, correct the wall temperature in the one-dimensional simulation model, which will change the intake state. This process requires multiple iterations to ensure that the error between the cylinder pressure and the experimental value within a range of 10° crankshaft angle before and after the start of combustion is less than 2%.

[0028] S4. Establish a three-dimensional structural simulation model of the air-cooled cylinder components and calculate the thermal-mechanical load of each component.

[0029] In finite element analysis software, the calculated temperature, heat transfer rate, and measured cylinder pressure are used as the inner wall temperature boundary conditions. The thermo-mechanical load of each component is calculated and compared with its material properties to determine whether the thermo-mechanical load meets the requirements. The outer boundary is air, and the outer wall temperature can be measured using a thermocouple.

[0030] S5. Within the allowable stress range of each component, a three-dimensional combustion simulation model is used to optimize the oil and gas chamber, and the thermal-mechanical load of each component is verified to obtain the optimized heat release rate.

[0031] After the wall temperature is calculated, the heat release rate is accurately calculated based on the experimentally measured cylinder pressure curve. A three-dimensional combustion simulation model is used to simulate the combustion process, and the heat release rate calculated using the measured cylinder pressure is calibrated. Combustion simulation requires spray model calibration, and parameters such as spray penetration and cone angle must be accurate. Generally, this industry requires a calculation error of less than 10%, and under strict conditions, an error of less than 5%.

[0032] The optimization contents include but are not limited to injection pressure, nozzle direction, nozzle diameter and piston configuration. The turbulence model is selected The KH-RT model was used for the spray breakup model, and the SAGE model was used for the combustion model. The optimization process required adaptation to a three-dimensional structural simulation model of the air-cooled cylinder components for stress verification, and the power enhancement was achieved by increasing the cyclic injection volume within the allowable range.

[0033] After calibrating the 3D combustion simulation model, we perform fuel-air chamber matching simulations to optimize power, including power enhancement. For air-cooled engines with turbochargers, improving thermal efficiency and allowing more fuel to burn near top dead center will lower exhaust temperatures, necessitating additional post-injection to maintain the turbine's operating conditions. This post-injection ensures that the in-cylinder pressure at the moment the exhaust valve opens in the 3D combustion simulation remains the same as it was before. After iterative optimization, we perform 3D thermal-mechanical load verification to ensure that material tolerances are not exceeded.

[0034] After optimizing thermal efficiency, the calculated maximum thermal-mechanical load on components falls below the material's allowable upper limit. This allows for increased fuel injection, directly boosting power and ensuring energy supply to the turbocharger system. This eliminates the need for post-injection and reduces fuel supply system requirements. In this case, allowance for thermal-mechanical loads is made based on the application scenario after the enhanced air-cooled unit, such as a limit below 90% of the maximum allowable value.

[0035] In this power potential calculation, the turbocharger, intercooler, fuel supply system, and cylinder oil-gas chamber matching are all independent one-dimensional simulation modules, with only boundary condition information transmitted within the model. Therefore, after strengthening each module and modifying the corresponding simulation model module parameters, this method can still be used to quantitatively estimate the power improvement potential.

[0036] S6. Input the optimized heat release rate into the one-dimensional simulation model to quantitatively calculate the power enhancement potential of the air-cooled machine, which is the power enhancement potential estimation value.

[0037] The advantages and positive effects of the method for quantitatively estimating the power enhancement potential of an air-cooled machine described in the present invention are:

[0038] 1. It can quantitatively predict the power enhancement potential and determine whether the proposed enhanced air-cooled machine can meet the original enhancement target.

[0039] 2. The power quantitative estimation process is embedded in the three-dimensional structural simulation verification, which ensures that the air-cooled machine will not be damaged by insufficient cooling capacity of its cooling system after strengthening. When applying new materials, only the material property parameters in the model need to be changed.

[0040] 3. The data required for the quantitative estimation of power potential are design parameters and conventional bench test measurements. It has low requirements for the test system and low data acquisition cost.

[0041] 4. By using simulation calculations instead of orthogonal tests, the time and economic cost of the air-cooled machine power enhancement test and verification can be reduced, and potential safety hazards in the whole machine test process can be reduced.

[0042] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a flow chart of an embodiment of the present invention;

[0044] Figure 2 The data transmission direction is the main boundary condition of the embodiment of the present invention;

[0045] Figure 3 A one-dimensional simulation model of an air-cooled machine according to an embodiment of the present invention;

[0046] Figure 4 A three-dimensional combustion simulation model of an air-cooled machine according to an embodiment of the present invention;

[0047] Figure 5 3D structure simulation model of the air-cooled machine according to the embodiment of the present invention. DETAILED DESCRIPTION

[0048] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0049] Example

[0050] This embodiment uses a 12-cylinder air-cooled engine as an example for quantitatively estimating the power enhancement potential. This engine has a turbocharger system, a design compression ratio of 17, an original design rated operating condition single-cylinder cycle fuel injection volume of 119mg, and a power of 441kW.

[0051] like Figure 1 、 Figure 2 The quantitative estimation method of the power enhancement potential of the air-cooled machine includes the following steps:

[0052] S1. Conduct external characteristic test on an engine test bench to obtain the performance parameters of the air-cooled machine. Use a Siemens AC dynamometer and adopt the speed control mode to operate the air-cooled machine at a constant speed.

[0053] The cylinder pressure curve for the air-cooled engine was collected using a cylinder pressure sensor. An AVL combustion analyzer, equipped with a corner marker, was used for data acquisition. One data point was recorded every 0.1° of crankshaft rotation, resulting in a total of 7,200 data points collected over a single 720° crankshaft rotation cycle. Data were processed using AVL indicom post-processing software.

[0054] After the target operating condition stabilizes for 3 minutes, cylinder pressure data for 50 engine cycles are collected. Thermodynamic analysis is performed on each engine cycle one by one. After a preliminary calculation of the heat release rate curve, the arithmetic mean is taken as the heat release rate for that operating condition.

[0055] S2, such as Figure 3 The one-dimensional whole-machine simulation software GT-POWER was used to build a one-dimensional simulation model of the air-cooled machine. The model includes the complete engine body, combustion chamber, valve system, fuel supply system and turbocharging system.

[0056] Design parameters such as cylinder bore, stroke, compression ratio, and firing order are entered into the engine block model. The engine block model also incorporates a friction model, whose parameters are derived from cylinder pressure curve calculations and dynamometer measurements, and the model is calibrated.

[0057] The combustion chamber model includes both a combustion model and a heat transfer model. The in-cylinder combustion model uses a three-Weibull function model to ensure that the model fitting curve is consistent with the calculated heat release rate curve. The fuel injector model in the combustion chamber sets the injection timing, cycle injection amount, and injection pressure.

[0058] The model gas distribution system pipeline parameters are modeled based on the actual machine scan and converted into a one-dimensional model using GEM 3D. The main parameters include length and pipe diameter.

[0059] The MAP of the turbocharger system equipped with the model is provided by the manufacturer, and the remaining system modeling data are obtained based on the model design parameters.

[0060] After calibrating the one-dimensional simulation model, the result data in the valve train and air-cooled cylinder are calculated and collected, and the thermodynamic state parameter values ​​of the working fluid in the cylinder after the intake valve is closed are obtained.

[0061] S3, such as Figure 4 As shown in the figure, a 3D combustion simulation model of a single-cylinder combustion chamber was established using the 3D combustion simulation software Converge to calculate the thermodynamic state inside the combustion chamber during the compression stroke. The initial gas state was provided by the 1D simulation results, and the RNG k-ε model was used as the turbulence model.

[0062] Calibration was performed using a reverse-drag cylinder pressure curve on a hot engine dynamometer, and the inner wall temperature of the air-cooled engine was determined through iteration. The combustion start point for this air-cooled engine was 11 crankshaft degrees before top dead center (TDC). The iterative calculation maintained a pressure error of less than 2% within 10 crankshaft degrees before and after this point. The iterations were performed in 5K steps, ultimately determining the cylinder head bottom surface temperature at 585K, the piston temperature at 635K, and the cylinder liner temperature at 515K.

[0063] S4, such as Figure 5 As shown in the figure, a 3D structural simulation model of the air-cooled cylinder components (cylinder head, cylinder liner, and piston) was established. In ANSYS finite element structural analysis software, the calculated temperature and measured cylinder pressure were used as internal boundary conditions to calculate the thermal-mechanical loads of each component and compare them with their material properties to determine whether they allow for power increase. The calculation settings used a tetrahedral mesh, the calculation type was transient, and the boundary conditions were Class III boundary conditions, which set the wall temperature and heat transfer rate.

[0064] S5. Converge software was used to simulate the combustion process, using the KH-RT model for the spray breakup and the SAGE model for the combustion model. Calibration was performed using the heat release rate calculated using the measured cylinder pressure. After spray calibration, the 3D simulation results had an error of less than 5%, meeting the engineering accuracy requirements.

[0065] After calibrating the 3D combustion simulation model, the heat release rate was compared with that of a water-cooled machine of similar displacement. The model demonstrated a longer combustion duration, suggesting potential for improved thermal efficiency. A dual-swirl piston was selected for oil-gas chamber matching, and parameters such as injector aperture, number, and orientation were adjusted to predict power gains. Following iterative optimization, 3D thermo-mechanical stress verification was performed to ensure that material tolerances were within acceptable limits. Given the high reliability requirements, iterations were terminated when the value fell below 85% of the material's maximum allowable value, indicating completion of the optimization.

[0066] S6. Substituting the three-dimensional simulation calculation results into the one-dimensional simulation model, it is found that the optimization method is to change the piston shape, change the number of injector holes to 6, match the injection angle, and increase the cycle injection amount from 119mg to 126mg. After the optimization and enhancement is completed, the air cooler power value is 472.2kW, which is the estimated value of its power enhancement potential.

[0067] Therefore, the proposed method for quantitatively estimating the power enhancement potential of air-cooled machines employs digital simulation technology to quantitatively estimate the power enhancement potential of air-cooled machines, improving enhancement design efficiency. By integrating thermal-mechanical load calculations and verification into the power enhancement estimation, the enhancement design process verifies that the enhancement process remains within the permitted cooling capacity. This avoids discrepancies between the estimated enhancement potential and the actual operating conditions, reduces the risk of damage to the air-cooled machine during the enhancement design verification phase, mitigates economic losses, and avoids safety hazards.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for quantitatively estimating the power enhancement potential of an air-cooled machine, characterized in that: The following steps are involved: S1. Obtain the performance parameters of the air-cooled machine and the reverse-drag cylinder pressure curve of the air-cooled machine in the hot state through bench testing; calculate the preliminary heat release rate through thermodynamic analysis under the condition that the boundary parameters take empirical values; S2. Establish a one-dimensional simulation model of the air cooler based on the design parameters of the air cooler and the performance parameters in S1 to obtain the thermodynamic state parameters of the air cooler's thermodynamic cycle gas; S3. Based on the test results, a three-dimensional combustion simulation model is established to calculate the thermodynamic state parameters of the gas in the combustion chamber during the compression phase after the intake valve is closed. The model is then iterated with the one-dimensional simulation model to optimize the wall temperature. S4. Establish a three-dimensional structural simulation model of the air-cooled cylinder components and calculate the thermal-mechanical load of each component; S5. Use a three-dimensional combustion simulation model to optimize the oil and gas chamber within the allowable stress range of each component, and verify the thermal-mechanical load of each component to obtain the optimized heat release rate; S6. Input the optimized heat release rate into the one-dimensional simulation model to quantitatively calculate the power enhancement potential of the air cooler; The calculation of the wall temperature of the air-cooled machine is as follows: during the compression process, the heat transfer rate of the working medium in the cylinder to the wall is negative, the wall heats the gas, and the gas in the cylinder meets ； The heat transfer rate between the working fluid in the cylinder and the wall is equal to the sum of the change rate of the internal energy of the working fluid in the cylinder and the change rate of the work done by the piston on the working fluid; the wall temperature is adjusted so that the calculated pressure at the starting point of combustion in the three-dimensional combustion simulation model is equal to the measured pressure, and the wall temperature is corrected in the one-dimensional simulation model.

2. The method for quantitatively estimating the power enhancement potential of an air-cooled machine according to claim 1, characterized in that: In S1, the performance parameters of the air-cooled machine include the intake air flow rate and the cylinder pressure curve of the air-cooled machine under stable working conditions.

3. The method for quantitatively estimating the power enhancement potential of an air-cooled machine according to claim 2, characterized in that: In S1, the heat release rate calculation formula is: ； in, ; in, ; in, ; in, represents the differential, Represents the heat released by combustion, represents the crankshaft angle, Represents internal energy, represents the heat transfer, represents the amount of work done; represents the fuel heat release rate, Represents the speed of change of internal energy of the working medium in the cylinder, Represents the heat transfer rate between the working medium in the cylinder and the wall, Represents the changing speed of the working fluid doing work; is the measured cylinder pressure, Represents the real-time cylinder volume, Represents the heat dissipation area, represents the polynomial index, represents the rotation speed, Represents the part number, represents the heat transfer coefficient, represents the gas temperature in the cylinder, Representative parts The wall temperature.

4. A method for quantitatively estimating the power enhancement potential of an air-cooled machine according to claim 3, characterized in that: In S2, a one-dimensional simulation model of the air-cooled machine is established using the simulation software GT-POWER. The one-dimensional simulation model of the air-cooled machine includes a machine body, a combustion chamber, an exhaust pipe, an intake pipe, and a turbocharger system.

5. The method for quantitatively estimating the power enhancement potential of an air-cooled machine according to claim 4, characterized in that: In S3, the compression stroke is calibrated using the hot engine state reverse cylinder pressure curve to calculate the air cooler wall temperature.

6. A method for quantitatively estimating the power enhancement potential of an air-cooled machine according to claim 5, characterized in that: In S3, a three-dimensional combustion simulation model of a single-cylinder combustion chamber is established using the three-dimensional combustion simulation software converge, the initial gas state uses the simulation result of the one-dimensional simulation model, and the turbulence model uses the RNGk-ε model.

7. A method for quantitatively estimating the power enhancement potential of an air-cooled machine according to claim 6, characterized in that: In the one-dimensional simulation model, the wall temperature is corrected so that the error between the in-cylinder pressure and the experimental value within the range of 10° crank angle before and after the start of combustion is less than 2%.

8. A method for quantitatively estimating the power enhancement potential of an air-cooled machine according to claim 7, characterized in that: In the above-mentioned S4, when calculating the thermal-mechanical load of each component, the calculated wall temperature, heat transfer velocity and measured cylinder pressure are used as the inner wall boundary conditions.

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