A calibration system and method for measuring high-speed gas total temperature probe

Abstract

The present invention discloses a calibration system and method for measuring a high-speed gas total temperature probe, which relates to the field of aerodynamics technology, including an air compressor, an air storage tank, a pitot tube pressure sensor and a calibrated total temperature probe, wherein the air compressor is connected to the air storage tank through a shut-off valve, a pressure regulating valve and a throttle valve, the air storage tank is externally connected to a pressure sensor and a total temperature thermocouple, a section of a tapered pipe is arranged at the outlet of the air storage tank, the calibrated total temperature probe and the pitot tube pressure sensor are arranged in the outlet pipe of the tapered pipe, a resistance heating sleeve is installed at the downstream measuring section of the tapered pipe, and the air compressor supplies gas to the air storage tank. The present application provides a calibration system and method for measuring a high-speed gas total temperature probe, which can perform a calibration test of a high-speed gas total temperature probe, and has the advantages of simple structure, low cost, high efficiency, etc.

Description

Technical Field

[0001] The invention relates to the technical field of aerodynamics, and in particular to a calibration system and method for a probe for measuring the total temperature of high-speed gas. Background Art

[0002] With the deepening of energy conservation and emission reduction plans in transportation, exhaust gas turbocharging technology, as one of the important means to improve vehicle fuel economy, has been increasingly valued by the industry. The turbocharger includes a turbine and a compressor. The turbine drives the coaxial compressor to compress air under the drive of high-temperature exhaust gas, thereby increasing the engine's intake density and improving the engine's effective power and fuel economy. In the steady-state performance test of the turbocharger, it is necessary to measure the turbine flow characteristic curve and the adiabatic efficiency characteristic curve. This is to prepare for the engine OEM to simulate the matching of the turbocharger and the engine, and can also be used to evaluate the performance of the turbine. In measuring the characteristic curve of the turbine, the total temperature of the turbine inlet and outlet must be accurately measured. The current common measurement method is to use a total temperature probe for measurement. Ideally, the total temperature measurement device needs to be insulated from the outside, and the fluid is stagnant near the probe. In fact, it is impossible to meet this measurement environment. Therefore, there will be a measurement error, making the measured temperature lower than the actual stagnation temperature. Therefore, a method must be considered to correct the total temperature probe to ensure that the turbine thermal efficiency calculated by the actual measured temperature is not much different from the actual thermal efficiency.

[0003] Therefore, in view of this, the existing technology is studied and improved, and a calibration system and method for measuring the total temperature probe of high-speed gas is proposed, in order to achieve a more practical purpose. Summary of the invention

[0004] The object of the present invention is to provide a calibration system and method for a probe for measuring the total temperature of high-speed gas, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: comprising an air compressor, an air storage tank, a Pitot tube pressure sensor and a calibrated total temperature probe, the air compressor is connected to the air storage tank through a shut-off valve, a pressure regulating valve and a throttle valve, the air storage tank is externally connected to a pressure sensor and a total temperature thermocouple, a section of a tapered pipe is arranged at the outlet of the air storage tank, the calibrated total temperature probe and the Pitot tube pressure sensor are arranged in the outlet pipe of the tapered pipe, the calibrated total temperature probe is a shielded total temperature probe, a resistance heating sleeve is installed at the downstream measuring section of the tapered pipe, the resistance heating sleeve is used to heat the total temperature probe to be calibrated, so as to compensate for heat transfer and set a calibration zero point, the air compressor supplies air to the air storage tank, multiple composite material insulation layers are used to insulate the connecting pipe, and the tapered pipe can accelerate the fluid to the local sound speed at most. When the back pressure is determined, the outlet air flow rate can be controlled by adjusting the thermal parameters of the reducer inlet fluid to meet the test requirements. The Pitot tube pressure sensor measures the total pressure and static pressure at the reducer outlet, the total temperature thermocouple measures the gas tank temperature, and the pressure sensor measures the gas tank pressure.

[0006] Furthermore, the method comprises the following steps:

[0007] S1, check the pipeline. Since a large number of quick-connect joints are used for the connection of the pipeline, including the high-pressure pipeline upstream of the gas tank, the low-pressure pipeline downstream of the gas tank, and the gas hoses of each pressure sensor, in order to prevent dangerous situations and gas leakage caused by vibration during the test, the pre-tightening force of the quick-connect interface is checked and all valves (including the pressure regulating valve) are closed before each high-pressure gas is introduced;

[0008] S2, thermal compensation of total temperature probe, energize the heating jacket in static state, adjust the power of the heating jacket, make the temperature reading of the total temperature probe equal to the temperature reading of the thermocouple of the gas tank, and set the calibration zero point;

[0009] S3, system preheating. Since the pipeline spans a long distance, in order to reduce the impact of heat transfer, the entire system is turned on before the test begins, and the air compressor continues to supply air for a period of time. After the system is heated, the air compressor is turned off, the high-pressure gas is discharged, the valves (including the pressure regulating valve) are closed, and it is left idle for a period of time to allow the air compressor core and the pipeline to cool to a suitable temperature.

[0010] S4, adjust the pressure of the gas storage tank and record the data. After the air compressor resumes supplying gas, open the stop valve, adjust the pressure regulating valve and the throttle valve, quickly stabilize the pressure of the gas storage tank at a certain pressure value, and record the temperature of the gas storage tank and the calibrated total temperature probe temperature data;

[0011] S5, after the data recording is completed, turn off the air compressor, discharge the high-pressure gas, close the valve (including the pressure regulating valve), and let it stand for a while to allow the core of the air compressor and the pipeline to cool to a suitable temperature;

[0012] S6, repeat steps 4 and 5 to measure multiple working condition values, repeat the operation multiple times for each working condition, and take the average value to reduce the deviation;

[0013] S7, by comparing the air flow temperature measured by the downstream total temperature probe with the gas temperature measured by the upstream reference temperature probe, the difference |T1-T| is the measurement error of the total temperature probe under high flow rate.

[0014] Furthermore, the step S4 specifically includes:

[0015] By adjusting the pressure regulating valve and the throttle valve, the pressure of the gas tank is stabilized to a certain pressure value, and the outlet velocity of the reducer can be adjusted to a certain fixed value. The outlet velocity v of the reducer can be calculated by the static pressure and total pressure values ​​measured by the pitot tube at the outlet of the reducer. p is the gas pressure in the gas tank; T is the gas temperature in the gas tank; p0 and p s The total pressure and static pressure measured by the L-type Pitot tube can be used to obtain the local air flow velocity, as shown in the following formula:

[0016]

[0017] Where: R is the gas constant, which is 287 J / (kg·K); k is the adiabatic index of air, k=1.4.

[0018] Furthermore, in step S2, the heating jacket is a resistance-type heating jacket, which is used to compensate for the temperature difference caused by heat transfer between the total temperature probe to be calibrated and the total temperature thermocouple of the upstream gas storage tank, and determine the calibration zero point.

[0019] Furthermore, in step S4, the pressure of the gas storage tank is stabilized to a set value in order from small to large.

[0020] Furthermore, in step S7, linear fitting is performed using the least square method.

[0021] Furthermore, the stop valve is used to switch the pipeline and adjust the flow rate, the pressure-stabilizing valve is used to adjust the internal pressure of the gas storage tank to adjust the air flow rate at the outlet of the convergent pipe, and the throttle valve is used to adjust the gas flow rate.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: the present application provides a calibration system and method for measuring the total temperature probe of high-speed gas, and proposes a system and method for calibrating the total temperature probe of high-speed airflow in a downstream pipeline using a relatively static fluid as the airflow source at low temperature. In the turbine characteristic experiment, the probe for measuring the total temperature of the turbine inlet and outlet is calibrated using this method, which can greatly reduce the speed error. Since the temperature is low and the radiation error is small in the cold blow test, and the use of a heating sleeve and an insulation layer in the experiment can greatly reduce the heat transfer error, the measurement accuracy of the total temperature can be greatly improved, thereby obtaining a more accurate turbine insulation efficiency.

[0023] The measuring device has a simple structure, is easy to implement, stable and reliable, and has high measuring accuracy, and can be used for the calibration of total temperature probes in high-speed airflow environments in other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the principle structure of the high-speed gas total temperature probe calibration test bench of the present invention;

[0025] Figure 2 This is a calibration value data table of the total temperature probe of the present invention.

[0026] In the figure: 1-air compressor, 2-stop valve, 3-pressure regulating valve, 4-throttle valve, 5-pressure sensor, 6-total temperature thermocouple, 7-air storage tank, 8-reduction tube, 9-Pitot tube pressure sensor, 10-calibrated total temperature probe. DETAILED DESCRIPTION

[0027] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0028] like Figure 1-2 As shown, it includes an air compressor 1, a stop valve 2, a pressure-stabilizing valve 3, a throttle valve 4, a pressure sensor 5, a total temperature thermocouple 6, an air storage tank 7, a reducer 8, a Pitot tube pressure sensor 9 and a calibrated total temperature probe 10. The air compressor 1 is connected to the air storage tank 7 through the stop valve 2, the pressure-stabilizing valve 3 and the throttle valve 4. The pressure sensor 5 and the total temperature thermocouple 6 are externally connected to the air storage tank 7 to measure the pressure and temperature respectively. A section of reducer 8 is arranged at the outlet of the air storage tank 7. The calibrated total temperature probe 10 and the Pitot tube pressure sensor 9 are arranged in the outlet pipe of the reducer 8. A resistance heating sleeve 11 is installed at the downstream measuring section of the reducer 8. The air compressor 1 supplies air to the air storage tank.

[0029] A method for calibrating a probe for measuring the total temperature of a high-speed fluid, the specific implementation steps are as follows:

[0030] S1, check the pipeline. Since a large number of quick-connect joints are used for the connection of the pipeline, including the high-pressure pipeline upstream of the gas tank, the low-pressure pipeline downstream of the gas tank, and the gas hoses of each pressure sensor, in order to prevent dangerous situations and gas leakage caused by vibration during the test, the pre-tightening force of the quick-connect interface is checked and all valves are closed before each high-pressure gas is introduced.

[0031] S2, total temperature probe thermal compensation. In a static state, energize the heating jacket and adjust the power of the heating jacket to make the total temperature probe temperature reading equal to the gas tank temperature reading.

[0032] S3, system preheating. Since the pipeline spans a long distance, in order to reduce the impact of heat transfer, the entire system is turned on before the test begins, and the air compressor continues to supply air for a period of time. After the system is heated, the air compressor is turned off, the high-pressure gas is discharged, the valve is closed, and it is left idle for a period of time to allow the air compressor core and pipeline to cool to a suitable temperature.

[0033] S4, adjust the gas tank pressure and record the data. After the air compressor resumes supplying gas, open the stop valve, adjust the pressure regulating valve and the throttle valve, and quickly stabilize the gas tank pressure at 5kPa, 10kPa, 15kPa, 20kPa and 25kPa. Record the gas tank temperature T and the calibrated total temperature probe temperature T1 data.

[0034] Specifically, by adjusting the pressure regulating valve and the throttle valve, the pressure of the gas tank is stabilized to a certain pressure value, and the outlet velocity of the reducer can be adjusted to a certain fixed value. The outlet velocity v of the reducer can be calculated by the static pressure and total pressure values ​​measured by the pitot tube at the outlet of the reducer. p is the gas pressure in the gas tank; T is the gas temperature in the gas tank; p0 and p s The total pressure and static pressure measured by the L-type Pitot tube can be used to obtain the local air flow velocity, as shown in the following formula:

[0035]

[0036] Where: R is the gas constant, which is 287 J / (kg·K); k is the adiabatic index of air, k=1.4;

[0037] S5, after the data recording is completed, turn off the air compressor, exhaust the high-pressure gas, close the valve (including the pressure regulating valve), and let it stand for a while to allow the core of the air compressor and the pipeline to cool to a suitable temperature.

[0038] S6, repeat steps 4 and 5, repeat the operation 3 times for each working condition, and take the average to reduce the deviation.

[0039] S7, by comparing the air flow temperature measured by the downstream total temperature probe with the gas temperature measured by the upstream reference temperature probe, the difference |T1-T| is the correction value of the total temperature probe at high flow rate.

[0040] The ambient pressure is 102.45 kPa. During the test, the gas temperature of the gas tank is maintained between 20℃ and 25℃. The three test data are averaged. The calibration value data of the total temperature probe is as follows: Figure 1 shown.

[0041] The least square method is used to perform a linear fit on the measurement error of the new total temperature probe. The fitted line can be used for error correction, as shown in Eq.

[0042] E=3.30605×Ma-0.27842

[0043] The embodiments of the present invention are given for the purpose of illustration and description, and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

Claims

1. A calibration method for a probe for measuring the total temperature of a high-speed gas, characterized in that: The invention comprises an air compressor (1), an air storage tank (7), a pitot tube pressure sensor (9) and a calibrated total temperature probe (10), characterized in that the air compressor (1) is connected to the air storage tank (7) through a stop valve (2), a pressure regulating valve (3) and a throttle valve (4); the air storage tank (7) is externally connected to a pressure sensor (5) and a total temperature thermocouple (6); a section of a reducer (8) is provided at the outlet of the air storage tank (7); the calibrated total temperature probe (10) and the pitot tube pressure sensor (9) are provided in the outlet pipe of the reducer (8); the calibrated total temperature probe (10) is a shielded total temperature probe; a resistance heating sleeve is installed at the downstream measuring section of the reducer (8); the air compressor (1) supplies air to the air storage tank; and a plurality of composite material insulation layers are used to insulate the connecting pipe; The method comprises the following steps: Step S1, check the pipeline. Since a large number of quick-connect joints are used for the connection of the pipeline, including the high-pressure pipeline upstream of the gas storage tank, the low-pressure pipeline downstream of the gas storage tank, and the gas guide hoses of each pressure sensor, in order to prevent dangerous situations and gas leakage caused by vibration during the test, the pre-tightening force of the quick-connect interface is checked and all valves are closed before each high-pressure gas is introduced; Step S2, total temperature probe thermal compensation, in a static state, the heating jacket is powered on, the power of the heating jacket is adjusted, the temperature reading of the total temperature probe is equal to the temperature reading of the gas tank thermocouple, and the calibration zero point is set; Step S3, preheating the system. Since the pipeline spans a long distance, in order to reduce the impact of heat transfer, the entire system is turned on before the test begins, and the air compressor continues to supply air for a period of time. After the system is heated, the air compressor is turned off, the high-pressure gas is discharged, the valve is closed, and it is left idle for a period of time to allow the air compressor core and the pipeline to cool to a suitable temperature; Step S4, adjusting the pressure of the gas storage tank and recording data. After the air compressor resumes supplying gas, open the stop valve, adjust the pressure regulating valve and the throttle valve, quickly stabilize the pressure of the gas storage tank at a certain pressure value, and record the temperature of the gas storage tank and the calibrated total temperature probe temperature data; Step S5, after the data recording is completed, the air compressor is turned off, the high-pressure gas is discharged, the valve is closed, and the compressor is left idle for a period of time to allow the core of the air compressor and the pipeline to cool to a suitable temperature; Step S6, repeating steps 4 and 5 to measure multiple working condition values, repeating the operation multiple times for each working condition, and taking the average value to reduce the deviation; Step S7, by comparing the air flow temperature measured by the downstream total temperature probe with the gas temperature measured by the upstream reference temperature probe, the difference |T1-T| is the measurement error of the total temperature probe at high flow rate.

2. A calibration method for a probe for measuring the total temperature of high-speed gas according to claim 1, characterized in that: The step S4 specifically includes: By adjusting the pressure regulating valve and the throttle valve, the pressure of the gas tank is stabilized to a certain pressure value, and the outlet velocity of the reducer can be adjusted to a certain fixed value. The outlet velocity v of the reducer can be calculated by the static pressure and total pressure values ​​measured by the pitot tube at the outlet of the reducer. p is the gas pressure in the gas tank; T is the gas temperature in the gas tank; p0 and p s The total pressure and static pressure measured by the L-type Pitot tube can be used to obtain the local air flow velocity, as shown in the following formula: Where: R is the gas constant, which is 287 J / (kg·K); k is the adiabatic index of air, k=1.

4.

3. A calibration method for a probe for measuring the total temperature of high-speed gas according to claim 1, characterized in that: In step S2, the heating jacket is a resistance type heating jacket, which is used to compensate for the temperature difference caused by heat transfer between the total temperature probe to be calibrated and the total temperature thermocouple of the upstream gas storage tank, and determine the calibration zero point.

4. A calibration method for a probe for measuring the total temperature of high-speed gas according to claim 1, characterized in that: In step S4, the pressure of the gas storage tank is stabilized to a set value in order from small to large.

5. A calibration method for a probe for measuring the total temperature of high-speed gas according to claim 1, characterized in that: In step S7, linear fitting is performed using the least squares method.

6. A calibration method for a probe for measuring the total temperature of high-speed gas according to claim 1, characterized in that: The stop valve (2) is used to switch the pipeline and adjust the flow rate, the pressure regulating valve (3) is used to adjust the internal pressure of the gas storage tank to adjust the flow rate of the gas flow at the outlet of the convergent pipe (8), and the throttle valve (4) is used to adjust the gas flow rate.

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