A method for on-site calibration of performance parameters of a combustion chamber test system

Abstract

The present invention discloses a method for on-site calibration of the performance parameters of a combustion chamber test system, which belongs to the field of aviation engine metrology and testing. This method uses a field reference total temperature sensor to replace the working probe, and uses a thermocouple conversion switch to connect all the measuring points of the inlet and outlet field reference total temperature sensors in parallel, and then reversely measure the temperature difference between the inlet and outlet sections. The test state is adjusted to be consistent with the working probe test, and calibration test data is collected. The combustion efficiency and temperature distribution coefficient are calculated using the field reference sensor data to perform on-site calibration on the performance parameters measured by the working probe. This method is suitable for the calibration of the performance parameters of the combustion chamber test system, and solves the problem that the laboratory calibration results cannot be used for the correction of the real combustion chamber data due to factors such as environmental parameter coupling and probe clogging effect, and solves the problem of large uncertainty in the inlet and outlet temperature difference during the calibration of the combustion efficiency and temperature distribution coefficient, so that the on-site calibration results can be used for performance parameter correction.

Description

Technical Field

[0001] The invention relates to a method for on-site calibration of performance parameters of a combustion chamber test system, and belongs to the field of aviation engine metrology testing. Background Art

[0002] The ground test of aircraft engine combustion chamber components is an important part of the aircraft engine development system engineering. Ensuring the accuracy and traceability of the performance parameters of the combustion chamber test system during ground testing is critical for evaluating aircraft engine performance and improving aircraft engine design. Measuring the temperature at each cross-sectional position of the combustion chamber test system can monitor the working condition of the combustion chamber and avoid engine damage caused by local overheating. Performance parameters such as combustion efficiency and temperature distribution coefficient of the combustion chamber test system can be used to evaluate aircraft engine performance and serve as a basis for structural design or optimization and improvement. With the development of my country's aircraft engine technology, the requirements for the measurement of performance parameters of the combustion chamber test system are getting higher and higher, and more research has been done on the calibration methods of these performance parameters.

[0003] The existing method for calibrating the performance parameters of the combustion chamber test system is to simulate the working conditions of the combustion chamber test in the laboratory calibration wind tunnel, such as the gas flow rate and total airflow temperature, and directly transmit the highest defense standard (calibration wind tunnel system) to the working measuring instruments, including airflow temperature sensors, total pressure probes, etc. When the working measuring instruments are used in the complex environmental conditions of the combustion chamber test system, due to the influence of factors such as environmental parameter coupling, sensor / probe blockage and layout, the laboratory calibration results cannot be used for the correction of the performance parameter data of the actual combustion chamber test system, and there is a large deviation.

[0004] The calculation formula for the combustion efficiency of the combustion chamber test system is: The calculation formula of the temperature distribution coefficient of the combustion chamber test system is: where t in is the average temperature of the combustion chamber inlet section, t out is the average temperature of the combustion chamber outlet section, t f is the outlet temperature when the fuel is completely burned, t max It is the hot spot temperature of the outlet section. The important performance parameters of these two combustion chamber test systems require the use of the temperature difference data between the inlet and outlet sections of the combustion chamber. Due to the large temperature difference between the inlet and outlet sections of the combustion chamber and the harsh environment, the current method of using inlet and outlet total temperature sensors to measure the inlet and outlet section temperatures and then making a difference introduces many uncertainties and large errors, which distorts the measurement data of the performance parameters of the combustion chamber test system and loses the value of evaluating the performance of the combustion chamber. Summary of the invention

[0005] In view of the problem that existing laboratory calibration cannot simulate the real combustion chamber test environment and the temperature difference measurement deviation between the inlet and outlet is large, the present invention discloses a combustion chamber test system performance parameter on-site calibration method, aiming to improve the calibration accuracy of the combustion chamber test system performance parameters.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] This method uses a field reference total temperature sensor to replace the working probe. All the measuring points of the inlet and outlet field reference total temperature sensors are connected in parallel through a thermocouple conversion switch, and then the inlet and outlet cross-sectional temperature difference is measured in reverse series. The test state is adjusted to be consistent with the working probe test, and calibration test data is collected. The combustion efficiency and temperature distribution coefficient are calculated using the field reference sensor data to perform field calibration of the combustion chamber test system performance parameters measured by the working probe.

[0008] A method for on-site calibration of performance parameters of a combustion chamber test system, the specific steps are as follows:

[0009] Step 1: Install the inlet and outlet working total temperature probes at the combustion chamber test system installation positions respectively.

[0010] Install the inlet working total temperature probe on the corresponding mounting seat of the inlet section of the combustion chamber test system. Install the outlet working total temperature probe on the corresponding mounting seat of the outlet section of the combustion chamber test system.

[0011] Step 2: Install the status monitoring total pressure probe and total temperature probe on the inlet section of the combustion chamber test system

[0012] Two inlet total temperature probes and two inlet total pressure probes for status monitoring are installed on the inlet section. The total temperature probes are located at 0° and 180° of the section circumference, and the total pressure probes are located at 90° and 270° of the section circumference.

[0013] Step 3: Adjust the intake valve, fuel supply valve, and gas supply equipment of the combustion chamber test system to a stable state and conduct the first test.

[0014] Carry out the ignition preparation for the combustion chamber test system test, adjust the combustion chamber intake valve, fuel supply valve, and gas supply equipment to achieve a stable state. Then ignite and start the first run of the on-site calibration, control the air flow and fuel flow, make the intake temperature measured by the two inlet probes of the state monitoring reach the standard test condition, and make the intake pressure measured by the two inlet total pressure probes of the state monitoring reach the standard test condition and remain stable.

[0015] Step 4: Use the working probe to measure the total inlet and outlet temperature data, and calculate the temperature rise efficiency and temperature distribution coefficient parameters of the combustion chamber test system.

[0016] The acquisition system was used to record the fuel flow, air flow, and oil-gas ratio during the first start-up. The temperature value measured by the imported working total temperature probe was t win The temperature value measured by the outlet working total temperature probe is t wout , record the total temperature and total pressure values ​​measured by the two inlet total temperature probes and the two inlet total pressure probes used for status monitoring during the first test run, and then shut down the machine.

[0017] Step 5: Replace the working total temperature probe with the field reference total temperature sensor, use the reverse connection method to measure the temperature difference between the inlet and outlet sections, and conduct the second test

[0018] Remove the on-site working total temperature probes of the inlet and outlet sections and replace them with on-site reference total temperature sensors. All on-site reference total temperature sensors are made of platinum-rhodium thermocouple wires from the same batch, and the total blockage ratio of the wires extending into the flow channel does not exceed 4.5%. The on-site reference total temperature sensor of the outlet section adopts a double shielding cover structure with a length-to-diameter ratio of more than 8. Through the thermocouple conversion switch, the positive and negative electrodes of the thermocouples of all measuring points of the inlet on-site reference total temperature sensor are connected in parallel to obtain the average temperature of the inlet section, and the positive and negative electrodes of the thermocouples of all measuring points of the outlet on-site reference total temperature sensor are connected in parallel to obtain the average temperature of the outlet section. The inlet thermocouple parallel electrodes and the outlet thermocouple parallel electrodes are reversed to obtain the temperature difference between the outlet section and the inlet section, that is, the negative electrodes of the inlet and outlet section parallel electrodes are connected to the negative electrodes, and the potential difference between the two positive electrodes is the inlet and outlet temperature difference. All thermocouple measuring points are connected to the acquisition system on the other side of the thermocouple conversion switch.

[0019] Keep the total temperature probe and total pressure probe for status monitoring on the inlet section unchanged, and maintain the status of the combustion chamber intake valve and fuel supply valve in the first test run. Start the second test run with on-site calibration as soon as possible, and maintain the oil-gas ratio, fuel flow rate, and air flow rate of the first test run. Ignite and start the car, so that the combustion chamber test system reaches the standard operating conditions, and adjust the intake conditions so that the total temperature and total pressure values ​​measured by the two inlet total temperature probes and two inlet total pressure probes for status monitoring during the second test run differ by less than 1% from the values ​​measured in the first test run. Record the inlet and outlet temperature difference during the second start-up t pΔ Then switch the thermocouple switch and record the temperature value of the imported field reference total temperature sensor as t pin The temperature value measured by the on-site reference total temperature sensor at the outlet is t pout , where the hot spot temperature of the outlet section is t pmax , then shut down the machine.

[0020] Step 6: Use the data measured by the on-site reference sensor to calculate the temperature rise efficiency and temperature distribution coefficient to calibrate the performance parameters of the combustion chamber test system

[0021] The combustion chamber test system performance parameter η was calculated using the data from the on-site reference total temperature sensor during the second test run.Tp , δ p , and the combustion efficiency correction coefficient Δη=η is obtained by subtracting the performance parameters measured by the probe in the first test run Tw -η Tp , Temperature distribution coefficient correction value Δδ=δ w -δ p .

[0022] The main sources of calibration uncertainty of combustion efficiency are: the standard uncertainty component u(t pΔ ), the standard uncertainty component u(t pin ), the standard uncertainty component u(t f ), the combined standard uncertainty of combustion efficiency u(η Tp )for:

[0023]

[0024] The main sources of calibration uncertainty of the temperature distribution coefficient are: the standard uncertainty component u(t pΔ ), the standard uncertainty component u(t pout ), the standard uncertainty component u(t pmax ), the combined standard uncertainty of the temperature distribution coefficient u(δ p )for:

[0025]

[0026] By evaluating the uncertainty components in the calibration process, the calibration uncertainty is given and used to correct the performance parameters of the combustion chamber test system.

[0027] The beneficial effects of the present invention are:

[0028] 1. Thermocouple electrodes are connected in parallel to directly obtain the average temperature of the cross section. Compared with measuring the thermocouples at each measuring point separately and then averaging the values, the uncertainty components of the electrical measuring instrument are reduced from being introduced multiple times, making the calibration uncertainty smaller.

[0029] 2. The inlet and outlet temperature difference is obtained by reversely measuring the thermocouple potential of the inlet and outlet sections, which reduces one uncertainty component compared to measuring the inlet and outlet temperatures separately, making the calibration uncertainty smaller.

[0030] 3. The on-site calibration test conditions are the real engine combustion chamber environment, and the calibration data obtained is more realistic and can be used to correct the test data.

[0031] 4. Through the thermocouple conversion switch, all the measuring points of the inlet and outlet on-site reference total temperature sensors are connected in parallel and then the inlet and outlet cross-sectional temperature difference is measured in reverse series. By switching the thermocouple conversion switch, the inlet and outlet cross-sectional temperature difference and the inlet and outlet temperatures of each measuring point can be measured simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A flow chart of a method for on-site calibration of performance parameters of a combustion chamber test system provided in Example 1 of the present invention;

[0033] Figure 2 A schematic diagram of a combustion chamber test system performance parameter on-site calibration system for a combustion chamber test system performance parameter on-site calibration method provided in Example 1 of the present invention.

[0034] Figure 3 A schematic diagram of a double shielding cover structure with a length-to-diameter ratio of 8 or more is provided for a field reference total temperature sensor of a combustion chamber test system performance parameter field calibration method provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. The technical problems solved by the technical solution of the present invention and the beneficial effects are also described. It should be noted that the described embodiments are only intended to facilitate the understanding of the present invention and do not have any limiting effect on it.

[0036] This embodiment 1 provides a method for calibrating the performance parameters of a combustion chamber test system on site. Figure 1 As shown, the following steps are included:

[0037] A 5-point inlet total working temperature probe is installed at the inlet section of the combustion chamber test system, and a 5-point outlet total working temperature probe is installed at the outlet section.

[0038] Four five-point total temperature and total pressure composite probes for status monitoring are installed at the circumferential positions of 0°, 90°, 180°, and 270° on the inlet section of the combustion chamber test system. The total blockage ratio of all probes extending into the flow channel is 2.5%.

[0039] Connect all thermocouple joints at the inlet and outlet sections to the temperature acquisition system, and use pressure pipelines to connect the pressure joints of all total pressure probes to the pressure scanning valve.

[0040] Adjust the combustion chamber intake valve, fuel supply valve, and air supply equipment to a stable state. Then ignite and start the first on-site calibration, control the air flow and fuel flow, make the intake temperature measured by the four state monitoring probes reach the standard test condition of 628.3K, make the intake pressure measured by the four state monitoring probes reach the standard test condition of 645.5kPa, keep stable, and collect and record all test data.

[0041] The average temperature of the combustion chamber outlet section was measured by the total temperature probe at the first start-up. wout =1598.2K, the average temperature of the combustion chamber inlet section measured by the working inlet total temperature probe t win =635.4K, theoretical outlet temperature when fuel is completely burned t f =1823.2K, the outlet total temperature probe measures the hot spot temperature t of the outlet section wmax =1663.1K. The combustion efficiency η is calculated by using the data measured by the working probe. Tw is 81.1% and the temperature distribution coefficient δ w It is 0.067.

[0042] The working total temperature probe on the inlet section is removed and replaced with an inlet field reference total temperature sensor with 5 measuring points. The working total temperature probe on the outlet section is removed and replaced with an outlet field reference total temperature sensor with a double shielding cover structure with a length-to-diameter ratio of 15. The field reference total temperature sensors are made of type B thermocouples from the same batch, and the total blockage ratio of all probes extending into the flow channel is 2%.

[0043] Through the thermocouple conversion switch, the positive and negative electrodes of the five measuring points of the inlet field reference total temperature sensor are connected in parallel to obtain the average temperature of the inlet section. The positive and negative electrodes of all measuring points of the outlet field reference total temperature sensor are connected in parallel to obtain the average temperature of the outlet section. The inlet thermocouple parallel electrodes are connected in reverse series with the outlet thermocouple parallel electrodes to obtain the temperature difference between the outlet section and the inlet section. All thermocouple measuring points are connected to the acquisition system on the other side of the thermocouple conversion switch.

[0044] Keep the status monitoring probes on the inlet and outlet sections unchanged, and maintain the status of the intake valve and fuel supply valve during the first test run. Start the second test run of on-site calibration as soon as possible, and maintain the oil-gas ratio, fuel flow rate, and air flow rate of the first test run. Ignite and start the combustion chamber test system to reach the standard operating conditions, and monitor the intake temperature at 630.3K and the intake pressure at 645.3kPa, and maintain stability. Record the inlet and outlet temperature difference t during the second start-up process pΔ =914.3K, then switch the thermocouple conversion switch and record the temperature values ​​of all measuring points of the imported on-site reference total temperature sensor as t pin , the temperature value of all measuring points of the reference total temperature sensor at the export site is t pout .

[0045] The average temperature t of the combustion chamber outlet section is measured by the reference total temperature sensor at the outlet wout =1591.6K, the average temperature of the combustion chamber inlet section measured by the inlet reference total temperature sensor win = 658.5K, the hot spot temperature t of the outlet section is measured by the reference total temperature sensor at the outlet wmax=1663.8K. The combustion efficiency η is obtained by calculation Tp is 78.5% and the temperature distribution coefficient δ p The performance parameters of the combustion chamber test system under standard conditions were calibrated using the on-site reference total temperature sensor, and the combustion efficiency correction coefficient Δη=2.6% and the temperature distribution correction coefficient Δδ=-0.012 were calculated.

[0046] The combined standard uncertainty of combustion efficiency u(η Tp ) through the formula

[0047]

[0048] Calculate, where u(t pΔ ) is the standard uncertainty component introduced by the reverse-series method for measuring temperature difference, u(t pin ) is the standard uncertainty component of the average temperature of the inlet section, u(t f ) The standard uncertainty component of the theoretical outlet temperature when the fuel is completely burned.

[0049] The combined standard uncertainty of the temperature distribution coefficient u(δ p ) through the formula

[0050]

[0051] Calculate, where u(t pΔ ) is the standard uncertainty component introduced by the reverse temperature difference measurement, u(t pout ) is the standard uncertainty component of the average temperature of the outlet section, u(t pmax ) is the standard uncertainty component of the hot spot temperature at the outlet section.

[0052] After uncertainty evaluation, the combined standard uncertainty of the combustion efficiency of this on-site calibration test is u(η Tp )=1.7%(k=2), the combined standard uncertainty of the temperature distribution coefficient u(δ p )=2.5%(k=2). The combustion chamber test system performance parameter field calibration method was used to calibrate the combustion efficiency and temperature distribution coefficient parameters under the standard test conditions of inlet total temperature of 628.3K and inlet total pressure of 645.5kPa. The combustion efficiency correction factor and temperature distribution correction factor were obtained based on the real engine environment. The calibration uncertainty is small and can be used to correct the combustion efficiency and temperature distribution coefficient measurement values.

[0053] The specific description above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for on-site calibration of performance parameters of a combustion chamber test system, characterized in that: The following steps are included: Step 1: Install the inlet and outlet working total temperature probes at the combustion chamber test system installation positions respectively; Step 2: Install a status monitoring total pressure probe and a total temperature probe at the inlet section of the combustion chamber test system; Step 3: Adjust the intake valve, fuel supply valve and gas supply equipment of the combustion chamber test system to a stable state and conduct the first test; Step 4: Use the working probe to measure the total inlet and outlet temperature data, and calculate the temperature rise efficiency and temperature distribution coefficient parameters of the combustion chamber test system; Step 5: Replace the working total temperature probe with the on-site reference total temperature sensor, use the reverse connection method to measure the temperature difference between the inlet and outlet sections, and conduct a second test; The implementation method of step five is: Remove the on-site working total temperature probes at the inlet and outlet sections and replace them with on-site reference total temperature sensors; All field reference total temperature sensors are made of platinum-rhodium thermocouple wires from the same batch, and the total blockage ratio of the wires extending into the flow channel does not exceed 4.5%; The field reference total temperature sensor of the outlet section adopts a double shielding cover structure with a length-to-diameter ratio of more than 8; the positive and negative poles of the thermocouples of all measuring points of the inlet field reference total temperature sensor are connected in parallel through a thermocouple conversion switch to obtain the average temperature of the inlet section, and the positive and negative poles of the thermocouples of all measuring points of the outlet field reference total temperature sensor are connected in parallel to obtain the average temperature of the outlet section; The inlet thermocouple parallel electrodes and the outlet thermocouple parallel electrodes are connected in reverse series to obtain the temperature difference between the outlet section and the inlet section, that is, the negative electrodes of the inlet and outlet section parallel electrodes are connected to each other, and the potential difference between the two positive electrodes is the inlet and outlet temperature difference; all thermocouple measuring points are connected to the acquisition system on the other side of the thermocouple conversion switch; Keep the total temperature probe and total pressure probe for status monitoring on the inlet section unchanged, and keep the status of the combustion chamber intake valve and fuel supply valve unchanged during the first test run; Start the second test run of on-site calibration as soon as possible, maintaining the oil-air ratio, fuel flow rate, and air flow rate of the first test run; Ignite and start the test so that the combustion chamber test system reaches the standard operating condition, and adjust the intake conditions so that the total temperature and total pressure values ​​measured by the two inlet total temperature probes and two inlet total pressure probes for status monitoring during the second test run differ by less than 1% from those measured during the first test run; Record the inlet and outlet temperature difference during the second start-up t pΔ Then switch the thermocouple switch and record the temperature value of the imported field reference total temperature sensor. t pin The reference total temperature sensor temperature value at the outlet is t pout , where the hot spot temperature of the outlet section is t pmax , then shut down and stop the machine; Step 6: Use the data measured by the on-site reference sensor to calculate the temperature rise efficiency and temperature distribution coefficient to calibrate the performance parameters of the combustion chamber test system; The implementation method of step six is: The combustion chamber test system performance parameters were calculated using the data from the on-site reference total temperature sensor during the second test run. , , and the combustion efficiency correction coefficient is obtained by subtracting the performance parameters measured by the working probe in the first test run , Temperature distribution coefficient correction value ; The sources of calibration uncertainty of combustion efficiency are: standard uncertainty component introduced by reverse temperature difference measurement u ( t pΔ ), standard uncertainty component of the average temperature of the inlet section u ( t pin ), standard uncertainty component of theoretical outlet temperature when the fuel is completely burned u ( t f ), the combined standard uncertainty of combustion efficiency for: The sources of calibration uncertainty of the temperature distribution coefficient are: standard uncertainty component introduced by the reverse temperature difference measurement method u ( t pΔ ), standard uncertainty component of the average temperature of the outlet section u ( t pout ), standard uncertainty component of the hot spot temperature at the outlet section u ( t pmax ), the combined standard uncertainty of the temperature distribution coefficient for: By evaluating the uncertainty components in the calibration process, the calibration uncertainty is given and used to correct the performance parameters of the combustion chamber test system.

2. A method for on-site calibration of performance parameters of a combustion chamber test system according to claim 1, characterized in that: The implementation method of step 2 is: Two inlet total temperature probes and two inlet total pressure probes for status monitoring are installed on the inlet section. The total temperature probes are located at 0° and 180° of the section circumference, and the total pressure probes are located at 90° and 270° of the section circumference.

3. A method for on-site calibration of performance parameters of a combustion chamber test system according to claim 1, characterized in that: The implementation method of step three is: Prepare for the combustion chamber test system test ignition, adjust the combustion chamber intake valve, fuel supply valve, and air supply equipment to a stable state; then ignite and start the first on-site calibration, control the air flow and fuel flow, make the two inlet probes for status monitoring measure the intake temperature to reach the standard test condition, make the two inlet total pressure probes for status monitoring measure the intake pressure to reach the standard test condition and remain stable.

4. A method for on-site calibration of performance parameters of a combustion chamber test system according to claim 1, characterized in that: The implementation method of step 4 is: The acquisition system was used to record the fuel flow, air flow, and oil-gas ratio during the first start-up. The temperature value measured by the imported working total temperature probe was t win ， The temperature measured by the outlet working total temperature probe is t wout ， Record the total temperature and total pressure values ​​measured by the two inlet total temperature probes and the two inlet total pressure probes used for status monitoring during the first test run, and then shut down the machine.

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