Ground-based method for calibrating high-altitude flight data of aircraft

Abstract

This invention discloses a method for calibrating high-altitude operational data of aircraft based on ground testing, comprising the following steps: S1, simulating various altitude environments and selecting different operating conditions; S2, calibrating operational data under different altitude environments and operating conditions; wherein, in S2, the operational data includes fuel injection quantity. When calibrating the fuel injection quantity, an operating condition is selected, and the optimal fuel injection quantity is first set as the initial value in a 0-altitude environment. Then, adjustments are made based on the initial value, and the fuel injection quantity under the same operating conditions at various altitudes is determined according to the changes in aircraft power. The calibration process of this invention is relatively simple, the adjustment basis is reliable, the adjustment efficiency is high, and the results are reliable, ensuring the reliability of high-altitude flight of the aircraft.

Description

Technical Field

[0001] This invention relates to a method for calibrating high-altitude operational data of aircraft, specifically a method for calibrating high-altitude operational data of aircraft based on ground testing. Background Technology

[0002] Aircraft are devices that fly within or outside the atmosphere, primarily including fixed-wing aircraft, helicopters, and unmanned aerial vehicles (UAVs). Because aircraft encounter highly variable environments and their altitudes constantly change during flight, the environmental variations they face are significant. Therefore, to ensure normal flight and reliable operation, it is necessary to adjust the aircraft's operational data in a timely manner. Currently, to determine the engine's operating envelope at various altitudes, high-altitude tests are typically conducted to confirm engine calibration data. Since aircraft typically fly at altitudes above 5000m, completing high-altitude tests from 1000m to 5000m requires at least two weeks, a lengthy process.

[0003] Chinese patent document CN106777821A discloses a method for calculating the ignition fuel supply for high-altitude start-up of an aircraft turbofan engine, relating to the field of engine starting technology. The invention includes the following steps: Step 1, calculating the percentage of oxygen content in the air relative to the oxygen content at sea level when the aircraft is at altitude H during engine start-up; Step 2, calculating the ignition fuel supply for engine start-up at altitude H based on the percentage; Step 3, calculating the amount of engine power reduction due to increased altitude and / or increased intake air temperature; calculating the impact of the reduced starter power on the engine's initial ignition fuel supply speed; calculating the impact of changes in the engine's initial ignition fuel supply speed on the inlet airflow; Step 4, correcting the calculation results of Step 2 based on changes in inlet airflow to obtain the final ignition fuel supply at altitude H. The advantage of this invention is that it can improve the success rate of engine ignition and start-up at high altitudes.

[0004] Another Chinese patent document, CN114046862B, discloses a high-precision fuel mass flow rate measurement correction method. This invention utilizes the influence of temperature and pressure on fuel density to perform temperature and pressure correction compensation for fuel density, obtaining a corrected density. Then, it utilizes the influence of temperature and pressure on fuel viscosity to perform temperature and pressure correction compensation for the volumetric flow rate of a turbine flow meter, obtaining a corrected volumetric flow rate value. Finally, based on the corrected density and the corrected volumetric flow rate value, the true fuel mass flow rate is obtained, serving as a control indicator for fuel flow in aero-engines, thus improving the measurement accuracy of fuel mass flow rate.

[0005] Furthermore, Chinese patent document CN115014788B discloses a correction control method for calculating fuel injection quantity of a port-injected engine at different altitudes. This method optimizes the pressure correction control of fuel injection quantity under different environmental pressures. It creatively introduces a correction curve for the difference between intake manifold pressure and fuel rail pressure into the model calculation. By accurately calibrating the correction values ​​for different altitudes and intake manifold pressures, it ensures that the air-fuel ratio can be controlled at the theoretically optimal level at different altitudes. This invention is based on extensive road test data, including measurements at different ambient temperatures and altitudes. Through big data statistical cluster analysis, it was found that the key factor affecting the accurate calculation of fuel quantity in a port-injected engine is the pressure difference between the fuel rail pressure and the intake manifold. This method can improve fuel economy at high altitudes while ensuring high power output in high-altitude environments.

[0006] Although the aforementioned prior art can adjust the operating data of the aircraft at different altitudes, including the ignition and fuel supply, through different adjustment methods, the adjustment methods in the aforementioned prior art are relatively complex and the adjustment efficiency needs to be improved. Summary of the Invention

[0007] To address the technical problem of the complexity of existing methods for adjusting operational data during high-altitude flight of aircraft, this invention provides a ground-based method for calibrating high-altitude operational data of aircraft, comprising the following steps: S1. Simulate environments at various altitudes and select different operating conditions; S2. Calibrate operating data under different altitude environments and different working conditions; In S2, the operating data includes the fuel injection quantity. When calibrating the fuel injection quantity, the operating condition is selected. First, the optimal fuel injection quantity is set as the initial value in the 0-altitude environment. Then, it is adjusted based on the initial value. The fuel injection quantity under the same operating condition at each altitude is determined according to the change of the aircraft power.

[0008] Since the optimal values ​​of the aircraft's operational data can be directly obtained from the actual flight process at 0 altitude, this scheme, when calibrating the aircraft's operational data at different altitudes, first selects the optimal operational data at 0 altitude as the adjustment basis. Then, based on this adjustment, the operational data for each altitude condition is determined according to the changes in the aircraft's power. Compared with existing technologies, this scheme has a simpler adjustment process, a reliable adjustment basis, high adjustment efficiency, and reliable results, ensuring the reliability of the aircraft's high-altitude flight.

[0009] Preferably, in step S2, the initial value of the fuel injection quantity is selected as the median value. Since the adjustment may be adjusted upwards or downwards based on the operating data used as the basis for adjustment during the adjustment process, setting the initial value to the median value in this solution ensures that the margin for upward or downward adjustment is the same, thereby ensuring the normal operation of the adjustment.

[0010] Preferably, in step S2, the initial value is adjusted by enriching or thinning it according to a preset step size. This solution achieves the adjustment of the fuel injection quantity through enrichment or thinning operations, which is simple to operate.

[0011] Preferably, in S2, the initial value is set to the same value as the gas density at the current altitude. Since the optimal air-fuel mixture ratio in the cylinder is usually around 1 when the aircraft engine is working normally, in this solution, at 0 altitude, the initial value of the fuel injection quantity is set to be the same as the gas density, achieving an air-fuel mixture ratio of 1. Adjustments are then made based on this adjustment, thereby ensuring the accuracy of the adjusted fuel injection quantity.

[0012] Preferably, in step S2, the operating data also includes the ignition angle. When calibrating the ignition angle, a specific operating condition is selected. First, combustion is adjusted to its optimal value at 0 altitude to determine the optimal ignition angle. Then, the initial values ​​under the same operating conditions at various altitudes are set as the optimal ignition angle value at 0 altitude. Adjustments are made based on these initial values, and the fuel injection quantity under the same operating conditions at various altitudes is determined according to the changes in aircraft power. This solution can achieve ignition angle calibration at various altitudes and is simple to operate.

[0013] Preferably, during the calibration of the ignition angle, the adjustment is made by advancing or retreating the initial value according to a preset step size. This solution achieves ignition angle adjustment by advancing or retreating the ignition angle, making the operation simple.

[0014] Preferably, in step S2, the operating data also includes the fuel injection angle. When calibrating the fuel injection angle, a specific operating condition is selected. At 0 altitude, combustion stability is adjusted to its optimal value, takeoff power is adjusted to its optimal value, and fuel consumption rate is adjusted to its lowest value. The fuel injection angle at this point is set as the optimal value. Then, the initial values ​​under the same operating conditions at various altitudes are set as the optimal fuel injection angle value at 0 altitude. Adjustments are made based on the initial values, and the fuel injection angle under the same operating conditions at various altitudes is determined according to the changes in aircraft power. This solution can calibrate the fuel injection angle at various altitudes and is simple to operate.

[0015] Preferably, during the calibration of the injection angle, the injection angle is adjusted forward or backward according to a preset step size based on the initial value. This solution achieves the adjustment of the injection angle by advancing or retracting the injection angle, making the operation simple.

[0016] The present invention has the following beneficial effects: In this invention, when calibrating aircraft operation data under different altitude environments, the optimal operation data at 0 altitude is first selected as the adjustment basis. Then, based on this adjustment, the operation data for each altitude condition is determined according to the change in aircraft power. Compared with the prior art, the calibration process of this invention is simpler, the adjustment basis is reliable, the adjustment efficiency is high, and the results are reliable, ensuring the reliability of high-altitude flight of the aircraft. Detailed Implementation

[0017] The following detailed description illustrates the specific implementation method: 1. Definition Operating envelope: refers to the flight performance envelope of an aircraft. It is a closed geometric figure formed by the performance limits and operational constraints of an aircraft, with parameters such as flight speed, altitude, and overload as coordinate axes. It is a key tool for describing the safe operating boundaries of an aircraft.

[0018] Fuel injection quantity: This is a core control parameter of the engine fuel system, referring to the amount of fuel injected into the cylinder in each cycle. It is the mass or volume of fuel that enters the combustion chamber after being atomized by the fuel injector, directly affecting the air-fuel ratio and engine power output. It is usually expressed in mg / st (milligrams per stroke) or cc / st (cubic centimeters per stroke).

[0019] Step size: refers to the magnitude of change in each adjustment.

[0020] Ignition angle: refers to the angle through which the crankshaft rotates from the moment the spark plug ignites until the piston reaches top dead center of the compression stroke. Its core function is to ensure that the maximum pressure generated by the combustion of the air-fuel mixture occurs during the piston's downward stroke (10°-15° after top dead center), in order to optimize engine power, economy, and emissions performance.

[0021] Injection angle: refers to the crankshaft angle between the piston and the top dead center (TDC) of the compression stroke when the injector starts injecting fuel. Its core function is to ensure that fuel enters the combustion chamber at the optimal time to achieve efficient combustion and power output.

[0022] 0 altitude means 0 meters above sea level; 1000 altitude means 1000 meters above sea level, and so on.

[0023] 2. The basic implementation method is as follows: A method for calibrating high-altitude flight data of aircraft based on ground testing, including the following steps: S1. Simulate environments at various altitudes and select different operating conditions; S2. Calibrate operating data under different altitudes and operating conditions; operating data includes fuel injection quantity, ignition angle, and fuel injection angle.

[0024] When calibrating the fuel injection quantity, a specific operating condition is selected. First, the optimal fuel injection quantity is set as the initial value at 0 altitude. This initial value is chosen to be the median value, which corresponds to the gas density at the current altitude. Then, adjustments are made based on this initial value, specifically by enriching or thinning the fuel injection quantity according to a preset step size. Finally, the fuel injection quantity at each altitude is determined based on the aircraft's power variation, specifically whether power decreases.

[0025] When calibrating the ignition angle, select an operating condition and first determine the optimal ignition angle value by adjusting combustion to the optimal value at 0 altitude. Then, set the initial value for the same operating condition at various altitudes as the optimal ignition angle value at 0 altitude. Adjust the ignition angle based on the initial value, specifically by advancing or retreating it according to a preset step size. Determine the ignition angle for the same operating condition at various altitudes based on the changes in aircraft power, i.e., whether the power decreases.

[0026] When calibrating the injection angle, select an operating condition. At 0 altitude, adjust combustion stability to its optimal value, power during takeoff to its optimal value, and fuel consumption rate during cruise to its lowest value. Set the injection angle at this point as the optimal value. Then, set the initial values ​​of the injection angles under the same operating conditions at various altitudes as the optimal value for the injection angle at 0 altitude. Adjustments are made based on these initial values, specifically, by advancing or regressing the injection angle according to a preset step size. The injection angle under the same operating conditions at various altitudes is determined based on the aircraft's power variation, i.e., whether power decreases.

[0027] The specific implementation process is as follows: The fuel injection quantity of the aircraft engine under various operating conditions at different altitudes is calibrated. The operating conditions selected are idle (3000 r / min), cruise (5000 r / min), and takeoff (6500 r / min). At 0 altitude, the fuel injection quantity is set to the median value to ensure the same margin for enrichment or leaning. The initial value of the fuel injection quantity and the gas density are set to be the same for each operating condition at the same altitude. Then, enrichment or leaning is performed in 5% increments based on the initial value of the fuel injection quantity. In other embodiments, enrichment or leaning can also be performed in other preset increments. The calibrated value of the fuel injection quantity for each operating condition at the same altitude is then confirmed based on whether power is reduced. The calibration results are shown in Table 1.

[0028] Table 1. Relationship between fuel injection quantity at various altitudes and fuel injection quantity at 0 altitude In Table 1, taking an altitude of 1000 meters as an example, the gas density at an altitude of 1000 meters is 0.91 times that at an altitude of 0 meters, and the fuel injection amount is 0.84 to 0.93 times that at an altitude of 0 meters.

[0029] The ignition angle of the aircraft engine under various operating conditions at different altitudes was calibrated. The operating conditions selected were idle (3000 r / min), cruise (5000 r / min), and takeoff (6500 r / min). At 0 altitude, the engine combustion was adjusted to its optimal value, i.e., the combustion parameter AI50 measured by the combustion analyzer was between 6° and 7°. The ignition angle at this point was considered optimal. The initial ignition angle value for each operating condition at the same altitude was set to the same as the optimal ignition angle value at 0 altitude. Then, based on the initial value, the ignition angle was advanced or de-advanced in steps of 3°. In other embodiments, other preset step sizes could also be used. The calibrated ignition angle value for each operating condition at the same altitude was confirmed based on whether power attenuation occurred. The calibration results are shown in Table 2.

[0030] Table 2 Relationship between ignition angles at different altitudes In Table 2, taking an altitude of 1000 meters as an example, the ignition angle at an altitude of 1000 meters is -3 to 0° off from the ignition angle at an altitude of 0 meters.

[0031] The fuel injection angle of the aircraft engine under various operating conditions at different altitudes was calibrated. The operating conditions selected were idling (3000 r / min), cruise (5000 r / min), and takeoff (6500 r / min). The combustion stability under idling was adjusted to the optimal value, the power under takeoff was adjusted to the optimal value, and the fuel consumption rate under cruise was adjusted to the lowest value. The fuel injection angle at these values ​​is the optimal value. The initial value of the fuel injection angle for the same operating condition at each altitude was set the same as the fuel injection angle at 0 altitude. Then, based on the initial value, it was advanced or retreated in steps of 10°. In other embodiments, other preset step sizes could also be used. The calibrated value of the fuel injection angle for the same operating condition at each altitude was then confirmed based on whether the power decreased. The calibration results are shown in Table 3.

[0032] Table 3 Relationship between injection angles at different altitudes In Table 3, taking an altitude of 1000 meters as an example, the fuel injection angle offset is the same as that at an altitude of 0 meters.

[0033] Two different aircraft engine models were selected, namely engine model 1 and engine model 2. Based on the aforementioned operational data calibration method, the ignition angle, injection angle, and fuel injection quantity of engine model 1 were set for idle, cruise, and takeoff conditions. This model has already completed 6 hours of cruise flight, maximum speed flight, and climb flight from 1500m to 4500m with a 50kg-class fixed-wing aircraft. Specific calibration results are shown in Table 4.

[0034] Table 4 In Table 4, taking the 0-altitude idling condition as an example, the ignition angle -30° represents 30° before the piston's top dead center, the injection angle -140° represents 140° before the piston's top dead center, and the fuel quantity 1 represents the fuel quantity based on the 0-altitude environment. The fuel quantity of 0.93 at the 1000-altitude environment represents 93% of the fuel quantity based on the 1000-altitude environment.

[0035] Based on the above-mentioned operational data calibration method, the ignition angle, injection angle, and fuel injection quantity of engine model 2 were set for idle, cruise, and takeoff conditions. This model has completed 24 hours of cruise flight, maximum speed flight, climb flight from 1500m to 7000m, and takeoff and landing flight from 5000m with an 80kg-class fixed-wing aircraft. The specific calibration results are shown in Table 5.

[0036] Table 5 In Table 5, taking the 0-altitude idling condition as an example, the ignition angle -24° represents 24° before the piston's top dead center, the injection angle -130° represents 130° before the piston's top dead center, and the fuel quantity 1 represents the fuel quantity based on the 0-altitude environment. The fuel quantity of 0.93 at the 1000-altitude environment represents 93% of the base fuel quantity at the 1000-altitude environment.

[0037] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for calibrating high-altitude operational data of aircraft based on ground testing, comprising the following steps: S1. Simulate environments at various altitudes and select different operating conditions; S2. Calibrate operating data under different altitude environments and different working conditions; The feature is that: in S2, the operating data includes the fuel injection quantity. When calibrating the fuel injection quantity, the operating condition is selected, and the optimal fuel injection quantity is first set as the initial value in the 0 altitude environment. Then, the adjustment is made based on the initial value, and the fuel injection quantity under the same operating condition at each altitude is determined according to the change of the aircraft power. In S2, the operating data also includes the ignition angle. When calibrating the ignition angle, the operating condition is selected, and the combustion is first adjusted to the optimal value in the 0-altitude environment to determine the optimal value of the ignition angle. Then, the initial value under the same operating condition in various altitude environments is set as the optimal value of the ignition angle in the 0-altitude environment. Adjustments are made based on the initial value, and the fuel injection quantity under the same operating condition in various altitudes is determined according to the change of the aircraft power.

2. The method for calibrating high-altitude flight data of aircraft based on ground testing according to claim 1, characterized in that: In S2, the initial value of the fuel injection quantity is selected to be the median value.

3. The method for calibrating high-altitude flight data of aircraft based on ground testing according to claim 2, characterized in that: In S2, the initial value is adjusted by increasing or decreasing the concentration based on the initial value according to a preset step size.

4. The method for calibrating high-altitude flight data of an aircraft based on ground testing according to any one of claims 1-3, characterized in that: In S2, the initial value is set to the same value as the gas density under the current altitude environment.

5. The method for calibrating high-altitude flight data of an aircraft based on ground testing according to claim 4, characterized in that: During the calibration of the ignition angle, the initial value is adjusted forward or backward according to a preset step size.

6. The method for calibrating high-altitude flight data of an aircraft based on ground testing according to claim 5, characterized in that: In S2, the operating data also includes the fuel injection angle. When calibrating the fuel injection angle, a working condition is selected. In a 0-altitude environment, the combustion stability is adjusted to the optimal value, the power of the takeoff working condition is adjusted to the optimal value, and the fuel consumption rate of the cruise working condition is adjusted to the minimum value. The fuel injection angle at this time is set as the optimal value. Then, the initial value under the same working condition in various altitude environments is set as the optimal value of the fuel injection angle in a 0-altitude environment. Adjustments are made based on the initial value, and the fuel injection angle under the same working condition in various altitudes is determined according to the change of the aircraft power.

7. The method for calibrating high-altitude flight data of an aircraft based on ground testing according to claim 6, characterized in that: During the calibration of the injection angle, the initial value is adjusted forward or backward according to a preset step size.

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