Method for obtaining fuel flow under steady state condition of engine test bed

Abstract

The application discloses a method for obtaining fuel flow under steady state of an engine test bench, comprising the following steps: S1, inputting a calculation formula Wf(n)out=A*Wf(n-1)out+(1-A)*Wf(n)raw of the fuel flow in a control system of the engine test bench, and configuring a weight coefficient A of fuel flow values at different time points, wherein Wf(n)out is an output displayed fuel flow value at the nth time point, Wf(n-1)out is an output displayed fuel flow value at the (n-1)th time point, and Wf(n)raw is a fuel flow value measured by a flowmeter at the nth time point; S2, continuously collecting and recording the measured fuel flow values of the flowmeter of the engine test bench at different time points, and substituting the fuel flow values into the formula to calculate the fuel flow values at each time point. The method effectively reduces the fluctuation caused by interference signals, and obtains a relatively stable fuel flow value with small fluctuation amplitude.

Description

Technical Field

[0001] This invention relates to a method for obtaining fuel flow rate under steady-state conditions on an engine test bench. Background Technology

[0002] During aero-engine testing, fuel flow rate, as a crucial parameter for evaluating engine performance, is a key focus and requires precise measurement. Turbine flow meters, due to their fast dynamic response and high accuracy, are widely used in the fuel systems of aero-engine test benches. During testing, various interference factors, such as fuel pipeline layout, fluid flow and pipeline vibration, and gas chamber compression, can cause fluctuations in flow meter readings, ranging from ±1% to ±3%. To reduce these fluctuations and improve measurement accuracy, specific methods and measures are needed to minimize fuel flow rate fluctuations.

[0003] In existing technologies, devices and methods for stabilizing and reducing pressure fluctuations in the fuel system of a test bench mainly include pressure stabilizing tanks. However, in practical applications, pressure stabilizing tanks are not standard equipment in fuel systems due to their large size and high cost. Therefore, there is a need to provide a method for obtaining fuel flow under steady-state conditions on an engine test bench to obtain more accurate fuel flow parameters. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the flow meter in the fuel flow measurement process of the fuel system of the aero-engine test stand is prone to fluctuation, resulting in inaccurate fuel flow measurement results. The present invention provides a method for obtaining the fuel flow under steady-state operating conditions of the engine test stand.

[0005] The present invention solves the above-mentioned technical problems through the following technical solution:

[0006] This invention provides a method for obtaining fuel flow rate under steady-state conditions on an engine test bench, comprising the following steps:

[0007] S1. Input the fuel flow calculation formula Wf(n)out=A*Wf(n-1)out+(1-A)*Wf(n)raw into the control system of the engine test bench, and configure the weight coefficient A of the fuel flow values ​​at different times. In the formula: Wf(n)out is the fuel flow value displayed at time n, Wf(n-1)out is the fuel flow value displayed at time n-1, and Wf(n)raw is the fuel flow value measured by the flow meter at time n.

[0008] S2. Continuously collect and record the fuel flow measurement values ​​of the flow meter on the engine test bench at different times, and substitute them into the formula to calculate the fuel flow value at each time.

[0009] In this scheme, the fuel flow rate value is obtained through the above method. After the fuel flow rate reading is collected from the flow meter, different weights are assigned to the relatively stable fuel flow rate value and the real-time changing flow meter reading in chronological order. The weight of the flow meter reading at a single moment is reduced, thereby maintaining the stability of the fuel flow rate value during the steady-state operation of the entire engine, effectively reducing the fluctuations caused by interference signals, and obtaining a relatively stable fuel flow rate value with small fluctuation amplitude.

[0010] Preferably, in step S2, the fuel flow rate value Wf(n-1)out displayed at time n-1 and the fuel flow rate value measured by the flow meter at time n are obtained by substituting them into the above formula to calculate and output the fuel flow rate value Wf(n)out displayed at time n.

[0011] Preferably, in step S2, after the test starts, the initial time 1 is recorded, and the value of 0 is used as the fuel flow rate value at time 0. The value is substituted into the formula for calculation, and the output is displayed as Wf(1)out.

[0012] Preferably, the weighting coefficient A is a rational number between 0.5 and 1.

[0013] In this scheme, under steady-state conditions, since the engine speed remains relatively stable, the fuel flow demand also remains relatively stable. Taking time n as an example, the above fuel flow calculation formula adopts the method of increasing "inertia" to increase the weight of the fuel flow value at time n-1 (i.e., increase the weight of the already relatively stable reading) and weaken the flow weight at time n (i.e., weaken the weight of the real-time changing flow meter reading), so that the obtained fuel flow value is closer to the true value.

[0014] Preferably, when configuring the weight coefficient A, the value of the weight coefficient A at time n is greater than that at time n-1.

[0015] In this scheme, since the engine speed remains relatively stable under steady-state conditions, the longer the running time, the more stable the fuel consumption. By reducing the weight of the previous moment, the fluctuation amplitude of the fuel flow reading can be significantly reduced.

[0016] Preferably, the value of the weight coefficient A at time n is 0.05 greater than that at time n-1.

[0017] Preferably, the flow meter is connected to the control system of the engine test bench.

[0018] Preferably, the engine test stand has a fuel system, which includes the flow meter, fuel supply pipe, fuel supply device, and engine. The engine's fuel pump is connected to the fuel supply device via the fuel supply pipe. The fuel supply pipe has a flow meter for measuring fuel flow. The fuel supply pipe has a straight section of at least 8D in length from the inlet end of the flow meter to the fuel supply device, and a straight section of at least 4D in length from the outlet end of the flow meter to the engine, where D is the inner diameter of the fuel supply pipe.

[0019] In this scheme, the fuel system of the engine test bench adopts the above-mentioned structure, which can significantly reduce the turbulent flow of fuel in the fuel supply pipeline, making the fuel flow of the entire fuel system more stable, effectively reducing the fluctuation amplitude of the fuel flow reading of the flow meter, further reducing the uncertainty of the flow meter measurement value, improving the measurement accuracy without making major modifications to the fuel system, and is low in cost and easy to implement.

[0020] Preferably, the oil supply pipeline has a high-point pipeline section located above the flow meter, and a vent valve is provided at the high-point pipeline section.

[0021] In this solution, a vent valve is installed at the high point of the pipeline to prevent gas in the oil supply pipeline from interfering with the flow meter's measurement accuracy.

[0022] Preferably, the oil supply pipes located on both sides of the flow meter and at a distance of 8D-12D from the flow meter are fixed to the engine test bench or the ground.

[0023] In this solution, the above method is used to reduce the impact of vibration on fuel flow fluctuations during engine testing.

[0024] Preferably, the fuel system further includes an inflow control valve, a fuel filter, and an engine front-end control valve. The inflow control valve and the fuel filter are sequentially disposed on the fuel supply pipeline between the fuel supply device and the flow meter, and the engine front-end control valve is disposed between the flow meter and the engine.

[0025] In this solution, the timing of fuel flow in the fuel supply pipeline is controlled by the inlet control valve and the engine front control valve to avoid impacting the flow meter and affecting the measurement. Impurities in the fuel in the fuel supply pipeline are filtered by the fuel filter to prevent the flow meter from being blocked and affecting the measurement results.

[0026] Preferably, the fuel system further includes a fuel temperature regulating device for regulating the fuel temperature to a preset temperature.

[0027] In this scheme, the fuel temperature is maintained at a constant level by a fuel temperature regulating device to avoid the influence of temperature changes on the measurement results.

[0028] Preferably, the fuel system further includes a fuel pressure gauge and a fuel temperature gauge, which are disposed on the fuel supply pipeline between the fuel supply device and the flow meter;

[0029] The fuel pressure gauge is used to obtain the pressure of the fuel in the fuel supply pipeline, and the fuel temperature gauge is used to obtain the temperature of the fuel in the fuel supply pipeline.

[0030] In this solution, fuel parameters are obtained through a fuel pressure gauge and a fuel temperature gauge, which facilitates understanding the state of the fuel.

[0031] Preferably, the fuel system further includes a controller, which is signal-connected to the fuel thermometer and the fuel temperature regulating device. The controller is used to control the fuel temperature regulating device to regulate the fuel temperature in the fuel supply pipeline based on the temperature information transmitted by the fuel thermometer.

[0032] Preferably, the fuel temperature regulating device is a fuel cooler, which is located between the flow meter and the engine.

[0033] In this scheme, during the test, the temperature of the fuel will continue to rise after flowing through the engine fuel pump. According to the analysis of the test data, the reading of the flow meter will generally fluctuate more after the fuel temperature rises. In order to reduce the fluctuation and improve the measurement accuracy, the fuel needs to be kept at a low temperature to avoid large measurement fluctuations caused by excessively high temperature.

[0034] Preferably, the flow meter is a turbine flow meter.

[0035] The turbine flow meter used in this scheme has obvious advantages such as compact structure, intuitive and clear readings, high reliability, immunity to external power interference, lightning protection, and low cost.

[0036] The positive and progressive effects of this invention are as follows: After collecting the fuel flow readings from the flow meter using the above method, this invention assigns different weights to the relatively stable fuel flow values ​​and the real-time changing flow meter readings according to the chronological order, thereby reducing the weight of the flow meter readings at a single moment, thus maintaining the stability of the fuel flow values ​​during the entire steady-state operation of the engine, effectively reducing fluctuations caused by interference signals, and obtaining relatively stable fuel flow values ​​with small fluctuation amplitudes. Attached Figure Description

[0037] Figure 1This is a flowchart of a method for obtaining fuel flow rate on an engine test bench in an embodiment of the present invention.

[0038] Figure 2 This is a simplified structural diagram of the fuel system of the engine test bench in an embodiment of the present invention.

[0039] Figure 3 This is a schematic diagram comparing fuel flow fluctuations obtained using the method of this invention with fuel flow fluctuations not obtained using this method.

[0040] Explanation of reference numerals in the attached figures:

[0041] Oil supply device 1

[0042] Incoming flow control valve 2

[0043] Fuel filter 3

[0044] Fuel pressure gauge 4

[0045] Fuel temperature gauge 5

[0046] vent valve 6

[0047] Flow meter 7

[0048] Engine front control valve 8

[0049] Engine 9

[0050] Oil supply pipeline 10

[0051] Fuel temperature regulating device 11 Detailed Implementation

[0052] The present invention will be described more clearly and completely below by way of embodiments and in conjunction with the accompanying drawings, but the present invention is not limited to the scope of the embodiments thereon.

[0053] like Figure 1 As shown, this embodiment of the invention provides a method for obtaining fuel flow rate under steady-state conditions on an engine test bench, comprising the following steps:

[0054] S1. Input the fuel flow calculation formula Wf(n)out=A*Wf(n-1)out+(1-A)*Wf(n)raw into the control system of the engine test bench, and configure the weight coefficient A of the fuel flow values ​​at different times. In the formula: Wf(n)out is the fuel flow value displayed at time n, Wf(n-1)out is the fuel flow value displayed at time n-1, and Wf(n)raw is the fuel flow value measured by the flow meter at time n.

[0055] S2. Continuously collect and record the fuel flow measurement values ​​of the flow meter on the engine test bench at different times, and substitute them into the formula to calculate the fuel flow value at each time.

[0056] By obtaining the fuel flow value through the above method, after collecting the fuel flow reading of the flow meter, different weights are assigned to the relatively stable fuel flow value and the real-time changing flow meter reading according to the time sequence, reducing the weight of the flow meter reading at a single moment, thereby maintaining the stability of the fuel flow value during the steady-state operation of the entire engine, effectively reducing the fluctuations caused by interference signals, and obtaining a relatively stable fuel flow value with small fluctuation amplitude.

[0057] In step S2, the fuel flow rate value Wf(n-1)out displayed at time n-1 and the fuel flow rate value measured by the flow meter at time n are obtained by substituting them into the above formula to calculate and output the fuel flow rate value Wf(n)out displayed at time n.

[0058] In step S2, after the test starts, the initial time 1 is recorded, and the value of 0 is used as the fuel flow value at time 0. The value is substituted into the formula for calculation, and the output is displayed as Wf(1)out.

[0059] The weighting coefficient A is a rational number ranging from 0.5 to 1. Using this range, under steady-state conditions, since the engine speed and fuel flow demand remain relatively stable, taking time n as an example, the fuel flow calculation formula above increases the weight of the fuel flow value at time n-1 (i.e., increases the weight of the already relatively stable reading) by increasing "inertia," while weakening the weight of the flow at time n (i.e., weakens the weight of the real-time changing flow meter reading), making the obtained fuel flow value closer to the true value.

[0060] Since the engine speed remains relatively stable under steady-state conditions, fuel consumption becomes more stable over longer operating times. Therefore, reducing the weight of the previous time step can significantly reduce the fluctuation amplitude of the fuel flow reading. Thus, when configuring the weighting coefficient A, the value of the weighting coefficient A at time n is larger than that at time n-1. For example, the value of the weighting coefficient A at time n is 0.05 larger than that at time n-1.

[0061] The flow meter is connected to the control system of the engine test bench, which facilitates the uploading of the flow meter's data to the engine test bench's control system.

[0062] like Figure 2As shown, in this embodiment, the fuel system of the engine test bench includes the aforementioned flow meter 7, fuel supply pipe 10, fuel supply device 1, and engine 9. The fuel pump of engine 9 is connected to fuel supply device 1 via fuel supply pipe 10. The fuel supply pipe 10 has a flow meter 7 for measuring fuel flow rate. The fuel supply pipe 10 has a straight section of at least 8D in length from the inlet end of the flow meter 7 to the fuel supply device 1, and a straight section of at least 4D in length from the outlet end of the flow meter 7 to the engine 9, where D is the inner diameter of the fuel supply pipe 10. In this embodiment, the flow meter 7 is a turbine flow meter. Turbine flow meters have significant advantages such as compact structure, clear and intuitive readings, high reliability, immunity to external power interference, lightning protection, and low cost. The fuel system of the engine test bench adopts the above-mentioned structure, which can significantly reduce the turbulent flow of fuel in the fuel supply pipeline 10, making the fuel flow of the entire fuel system more stable, effectively reducing the fluctuation amplitude of the fuel flow reading of the flow meter 7, further reducing the uncertainty of the measured value of the flow meter 7, improving the measurement accuracy without making major modifications to the fuel system, and is low in cost and easy to implement.

[0063] The oil supply pipeline 10 has a high-point section located above the flow meter 7, and a vent valve 6 is installed at the high-point section. Installing the vent valve 6 at the high-point section prevents gas within the oil supply pipeline 10 from interfering with the measurement accuracy of the flow meter 7. The number of vent valves 6 depends on the routing of the oil supply pipeline 10 and the location of the high point. Generally, a section of the oil supply pipeline 10 with a "U"-shaped routing must have at least one vent valve 6 installed at the high point. The type of vent valve 6 is not specified; it can be a manual vent valve or an automatic vent valve with a pressure limit setting.

[0064] The fuel supply pipes 10 located on both sides of the flow meter 7, at a distance of 8D-12D from the flow meter 7, are fixed to the engine test bench or the ground to reduce the impact of engine vibration on fuel flow fluctuations during engine testing. In this embodiment, the fuel supply pipes 10 at the front and rear ends of the flow meter 7 are rigidly fixed to the ground or test bench using brackets at a distance of approximately 10D from the flow meter 7. To ensure smoother flow in the entire fuel system and reduce turbulent flow within the pipes, the entire fuel system uses straight pipes as much as possible, minimizing bends, sudden expansions, sudden contractions, and diameter changes.

[0065] The fuel system of the engine test bench also includes an inlet flow control valve 2, a fuel filter 3, and an engine front-end control valve 8. The inlet flow control valve 2 and the fuel filter 3 are sequentially installed on the fuel supply pipe 10 between the fuel supply device 1 and the flow meter 7. The engine front-end control valve 8 is located between the flow meter 7 and the engine 9. The inlet flow control valve 2 and the engine front-end control valve 8 control the timing of fuel flow in the fuel supply pipe 10 to avoid impacting the flow meter 7 and affecting the measurement. The fuel filter 3 filters impurities in the fuel in the fuel supply pipe 10 to prevent the flow meter 7 from being blocked and affecting the measurement results.

[0066] The engine test bench's fuel system also includes a fuel temperature regulating device 11, which is used to regulate the fuel temperature to a preset temperature. The fuel temperature regulating device 11 maintains the fuel temperature at a constant level, preventing temperature changes from affecting the measurement results.

[0067] In this embodiment, the fuel temperature regulating device 11 is a fuel cooler, which is located between the flow meter 7 and the engine 9. During the test, the fuel temperature continuously rises after flowing through the fuel pump of the engine 9. According to the test data analysis, the flow meter 7 reading generally fluctuates more significantly after the fuel temperature rises. To reduce fluctuations and improve measurement accuracy, the fuel needs to be maintained at a relatively low temperature to avoid excessive temperature fluctuations. Preferably, the fuel temperature needs to be controlled between 20℃ and 60℃. In addition to this temperature control requirement, the fuel cooler can be kept on throughout the test to maintain an even lower fuel temperature. Tests have shown that after the fuel is cooled by the fuel cooler and enters the engine, the engine's built-in fuel temperature monitoring value stabilizes at around 30℃. This stable inlet temperature, according to test data, has a significant effect on reducing the fuel flow reading.

[0068] The fuel system of the engine test bench also includes a fuel pressure gauge 4 and a fuel temperature gauge 5, which are installed on the fuel supply pipe 10 between the fuel supply device 1 and the flow meter 7. The fuel pressure gauge 4 is used to obtain the pressure of the fuel in the fuel supply pipe 10, and the fuel temperature gauge 5 is used to obtain the temperature of the fuel in the fuel supply pipe 10. Obtaining fuel parameters through the fuel pressure gauge 4 and the fuel temperature gauge 5 facilitates understanding the state of the fuel.

[0069] The controller of the fuel system on the engine test bench is connected to the fuel thermometer 5 and the fuel temperature regulating device 11. The controller is used to control the fuel temperature regulating device 11 to regulate the fuel temperature in the fuel supply pipeline 10 according to the temperature information transmitted by the fuel thermometer 5.

[0070] When the fuel system of the engine test bench is working, fuel is output through the fuel supply device 1, and then flows through the fuel supply pipe 10, through the inlet control valve 2, fuel filter 3, fuel pressure gauge 4, fuel temperature gauge 5, flow meter 7, engine front control valve 8, and finally flows into the fuel pump of the engine 9 after passing through the fuel temperature regulating device 11.

[0071] This invention increases the "inertia" of existing stable operating conditions and reduces the weight of real-time measurement values. Through experimental verification and data analysis and comparison, multiple sets of data show that the steady-state values ​​of data results obtained by using the method of this invention and those not using this method are close to 99.985%, with basically no deviation. This proves that the method is completely feasible in processing fuel flow results under steady-state operating conditions. Figure 3 The fuel flow fluctuation obtained by the method of this invention is compared with the fuel flow fluctuation without the method, and the amplitude is reduced by nearly 50%, which effectively reduces the fluctuation and improves the measurement accuracy.

[0072] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for obtaining fuel flow rate under steady-state conditions on an engine test bench, characterized in that, Includes the following steps: S1. Input the fuel flow calculation formula Wf(n)out=A*Wf(n-1)out+(1-A)*Wf(n)raw into the control system of the engine test bench, and configure the weight coefficient A of the fuel flow values ​​at different times. In the formula: Wf(n)out is the fuel flow value displayed at time n, Wf(n-1)out is the fuel flow value displayed at time n-1, and Wf(n)raw is the fuel flow value measured by the flow meter at time n. S2. Continuously collect and record the fuel flow measurement values ​​of the flow meter on the engine test bench at different times, and substitute them into the formula to calculate the fuel flow value at each time. In step S1, when the weight coefficient A is configured, the value of the weight coefficient A at time n is greater than that at time n-1, and the value of the weight coefficient A is a rational number between 0.5 and 1.

2. The method for obtaining fuel flow rate under steady-state conditions on an engine test bench as described in claim 1, characterized in that, In step S2, the fuel flow rate value Wf(n-1)out displayed at time n-1 and the fuel flow rate value measured by the flow meter at time n are obtained by substituting them into the above formula to calculate and output the fuel flow rate value Wf(n)out displayed at time n.

3. The method for obtaining fuel flow rate under steady-state conditions on an engine test bench as described in claim 1, characterized in that, In step S2, after the test starts, the initial time 1 is recorded, and the value of 0 is used as the fuel flow value at time 0. The value is substituted into the formula for calculation, and the output is displayed as Wf(1)out.

4. The method for obtaining fuel flow rate under steady-state conditions on an engine test bench as described in claim 1, characterized in that, The value of the weight coefficient A at time n is 0.05 greater than that at time n-1.

5. The method for obtaining fuel flow rate under steady-state conditions on an engine test bench as described in claim 1, characterized in that, The flow meter is connected to the control system of the engine test bench.

6. The method for obtaining fuel flow rate under steady-state conditions on an engine test bench as described in claim 1, characterized in that, The engine test stand has a fuel system, which includes the flow meter, fuel supply pipe, fuel supply device, and engine. The engine's fuel pump is connected to the fuel supply device via the fuel supply pipe. The fuel supply pipe has a flow meter for measuring fuel flow. The fuel supply pipe has a straight section of at least 8D in length from the inlet end of the flow meter to the fuel supply device, and a straight section of at least 4D in length from the outlet end of the flow meter to the engine, where D is the inner diameter of the fuel supply pipe.

7. The method for obtaining fuel flow rate under steady-state conditions on an engine test bench as described in claim 6, characterized in that, The oil supply pipeline has a high-point pipeline section located above the flow meter, and a vent valve is installed at the high-point pipeline section.

8. The method for obtaining fuel flow rate under steady-state conditions on an engine test bench as described in claim 6, characterized in that, The oil supply pipes located on both sides of the flow meter and at a distance of 8D-12D from the flow meter are fixed to the engine test bench or the ground.

9. The method for obtaining fuel flow rate under steady-state conditions on an engine test bench as described in claim 6, characterized in that, The fuel system also includes an inlet flow control valve, a fuel filter, and an engine front-end control valve. The inlet flow control valve and the fuel filter are sequentially disposed on the fuel supply pipeline between the fuel supply device and the flow meter, and the engine front-end control valve is disposed between the flow meter and the engine.

10. The method for obtaining fuel flow rate under steady-state conditions on an engine test bench as described in claim 6, characterized in that, The fuel system also includes a fuel temperature regulating device, which is used to regulate the fuel temperature to a preset temperature.

11. The method for obtaining fuel flow rate under steady-state conditions on an engine test bench as described in claim 10, characterized in that, The fuel system also includes a fuel pressure gauge and a fuel temperature gauge, which are installed on the fuel supply pipeline between the fuel supply device and the flow meter. The fuel pressure gauge is used to obtain the pressure of the fuel in the fuel supply pipeline, and the fuel temperature gauge is used to obtain the temperature of the fuel in the fuel supply pipeline.

12. The method for obtaining fuel flow rate under steady-state conditions on an engine test bench as described in claim 11, characterized in that, The fuel system also includes a controller, which is signal-connected to the fuel thermometer and the fuel temperature regulating device. The controller is used to control the fuel temperature regulating device to regulate the fuel temperature in the fuel supply pipeline according to the temperature information transmitted by the fuel thermometer.

13. The method for obtaining fuel flow rate under steady-state conditions on an engine test bench as described in claim 10, characterized in that, The fuel temperature regulating device is a fuel cooler, which is located between the flow meter and the engine.

14. The method for obtaining fuel flow rate under steady-state conditions on an engine test bench as described in any one of claims 1-13, characterized in that, The flow meter is a turbine flow meter.

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