A jet cooling control method for a jet precooling engine

Abstract

The present application belongs to the field of aero-engine design, and is a jet cooling control method for a jet pre-cooling engine. The method utilizes the aircraft altitude and flight speed to determine the total temperature and total pressure of the jet pre-cooling device's incoming flow, determines the fan's inlet air flow through the corresponding relationship between the fan's converted speed and the converted flow, and then obtains the initial cooling medium flow. Finally, the initial cooling medium flow is corrected by the total temperature after the fan, the fan pressure ratio, and the fan efficiency to obtain a more accurate actual total temperature before the fan. The method utilizes the inherent working characteristics of the engine and the onboard test parameters of conventional engines, and calculates the total temperature, total pressure, inlet air flow, and cooling medium flow as much as possible through existing parameters or parameters that can be conveniently and accurately measured. There is no need to consider temperature sensors, delays, and measurement errors, and the initial water volume is calculated more accurately. The test parameters after the fan, which contain a smaller amount of liquid water, are used to correct the water spray volume, thereby achieving high-precision water control.

Description

Technical Field

[0001] The present application relates to the field of aero-engine design, and in particular to a jet cooling control method for a jet pre-cooling engine. Background Art

[0002] When high-Mach-number aircraft fly at high Mach numbers, the incoming airflow temperature is high, exceeding the turbine engine's tolerable operating range. A jet-cooled engine is a device that injects a cooling medium (usually water or a water mixture) before the fan / compressor of a conventional turbine engine. This spray, atomization, and evaporation of the medium cools the higher-temperature airflow in the inlet duct, reducing or maintaining the total temperature of the airflow before entering the fan / compressor. This allows the engine to operate at a tolerable inlet airflow temperature, thereby extending the engine's operating range.

[0003] The jet precooler control system regulates the coolant flow rate based on the total incoming air temperature, flow rate, and target engine inlet temperature, keeping the total air temperature before the turbine engine fan below the maximum inlet temperature the turbine engine can withstand. High-Mach-number aircraft typically activate jet precooling during accelerated climbs. This means that the incoming airflow conditions of the jet precooler engine are constantly changing. To maintain a constant fan / compressor inlet temperature, the jet precooler must continuously adjust the jet flow rate.

[0004] like Figure 1-2 As shown, the existing jet precooling control scheme is generally a control scheme for jet precooling research experiments. A total temperature sensor 2 is arranged before the inlet of the fan 3 after the jet precooling device 1 to monitor the total temperature T of the fan inlet section (2-2 section). t2 When entering the jet pre-cooling mode, the total temperature before the fan inlet is set to T t2_Dem Closed loop water regulation, when the measured total temperature T t2 When the total temperature rake senses the change in the total temperature at the fan inlet when it deviates from the given value, the cooling medium flow rate is adjusted until the total temperature T after jet precooling is t2 Reach target value T t2_Dem Since the temperature measurement itself has a certain delay, and the total temperature measurement under the jet pre-cooling condition is affected by the water mist and has a large measurement error, this control method will cause the real-time cooling medium flow Wc and the fan inlet total temperature to deviate from the expected value, resulting in the fan conversion speed n 1r The test deviates from reality, resulting in a mismatch between the aircraft and the engine flow, which may cause engine surge in severe cases.

[0005] In order to solve the above engineering application problems, a jet cooling control method for a jet pre-cooling engine is proposed. Summary of the Invention

[0006] The purpose of this application is to provide a jet cooling control method for a jet pre-cooling engine to solve the problem in the prior art that the cooling medium flow, fan inlet temperature, and fan conversion speed deviate from expectations due to the delay in temperature measurement.

[0007] The technical solution of the present application is: a jet cooling control method for a jet precooling engine, comprising: obtaining the flight altitude H and flight speed Ma0 of the aircraft, calculating the total temperature T of the incoming flow of the jet precooling device, t1 and total pressure P t1 ; Get the target temperature T before the fan inlet t2_Dem Calculate the fan conversion speed n of the target fan 1r , according to the fan conversion speed n 1r And the converted flow rate W 2r The corresponding relationship is used to calculate the converted flow rate W of the fan. 2r , and further calculate the engine inlet air flow W2; according to the fan inlet air flow W2, the total temperature T of the jet precooling device t1 and the target temperature before the fan inlet T t2_Dem Calculate the initial cooling medium flow rate W c ;Measure and obtain the total temperature T after the fan t13 , and obtain the total pressure ratio π according to the engine operating characteristics f and fan efficiency η f , reconstruct the actual total temperature T before the fan t2c , using the actual total temperature T before the fan t2c Initial cooling medium flow rate W c Make corrections to obtain the actual cooling medium flow rate.

[0008] Preferably, the total temperature T of the flow from the jet device is t1 and total pressure P t1 The calculation formula is:

[0009]

[0010]

[0011] Where, P0 is the ambient static pressure; T0 is the ambient static temperature; P t1 is the total pressure of the incoming flow from the jet precooling device; T t1 is the total temperature of the incoming air before the jet precooling device; Ma0 is the flight Mach number of the aircraft; k is the specific heat ratio of the incoming air; σ i1 is the total pressure recovery coefficient of the front part of the inlet jet precooling device.

[0012] Preferably, the fan conversion speed n 1r Target temperature before the fan inlet T t2_DemThe engine inlet air flow rate W2 is calculated by the total pressure before the fan P t2 and target temperature T t2_Dem Calculated.

[0013] Preferably, the fan conversion speed n 1r The calculation formula is:

[0014]

[0015] The calculation formula of the inlet air flow rate W2 is:

[0016]

[0017] Among them, σ i2 is the total pressure recovery coefficient of the rear part of the inlet jet precooling device.

[0018] Preferably, the actual total temperature before the fan T t2c The calculation formula is:

[0019]

[0020] The present application provides a jet cooling control method for a jet pre-cooling engine, which utilizes the aircraft altitude and flight speed to determine the total temperature and total pressure of the jet pre-cooling device's incoming flow, determines the fan's inlet air flow through the corresponding relationship between the fan's converted speed and the converted flow, and then obtains the initial cooling medium flow, and finally corrects the initial cooling medium flow through the total temperature after the fan, the fan pressure ratio, and the fan efficiency to obtain a more accurate actual total temperature before the fan; utilizes the inherent working characteristics of the engine and the onboard test parameters of conventional engines, and calculates the total temperature, total pressure, inlet air flow, and cooling medium flow through existing parameters or parameters that can be conveniently and accurately measured as much as possible, without considering temperature sensors, delays, and measurement errors, and performs more accurate calculations on the given initial water volume, and uses the test parameters after the fan containing a smaller amount of liquid water to correct the water spray volume, thereby achieving high-precision water control. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions provided by this application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of this application.

[0022] Figure 1 Schematic diagram of the structure of the jet pre-cooling device in the background technology;

[0023] Figure 2 Schematic diagram of the jet pre-cooling control principle in the background technology;

[0024] Figure 3This is a schematic diagram of the overall process of this application;

[0025] Figure 4 This is a schematic diagram of the control principle of the jet control scheme of this application.

[0026] 1. Jet pre-cooling device; 2. Total temperature sensor; 3. Fan. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0028] A jet cooling control method for a jet precooling engine is proposed. An analysis of the jet precooling system shows that the control of the jet precooling system for engineering applications must solve two problems. First, the delay of the temperature sensor and the large temperature measurement error under jet precooling conditions will cause the engine working state to deviate. Second, the engineering application of jet precooling requires high-precision and fast-response jet precooling system control with fewer measurement parameters.

[0029] like Figure 3-4 As shown, the following steps are included:

[0030] Step S100, the total temperature T of the incoming flow from the jet precooling device t1 and total pressure P t1 calculate;

[0031] Preferably, the total temperature T of the incoming flow from the jet precooling device can be calculated by measuring the flight altitude H and flight speed Ma0 obtained by the aircraft. t1 and total pressure P t1 , the calculation formula is:

[0032]

[0033]

[0034] Where, P0 is the ambient static pressure; T0 is the ambient static temperature; P t1 is the total pressure of the incoming flow from the jet precooling device; T t1 is the total temperature of the incoming air before the jet precooling device; Ma0 is the flight Mach number of the aircraft; k is the specific heat ratio of the incoming air; σ i1 is the total pressure recovery coefficient of the front part of the inlet jet precooling device.

[0035] Since the flight height H and flight speed Ma0 data are used to calculate the total temperature T of the incoming flow of the jet precooling device t1 and total pressure P t1, rather than directly measuring, on the one hand avoids the delay problem of temperature measurement, and at the same time is not affected by water mist, so it can ensure greater measurement accuracy.

[0036] Step S200, calculating the engine inlet air flow rate W2;

[0037] Under the same control law, the common working line of the engine is determined, and there is a corresponding relationship between the converted flow and the converted speed of the engine. By using this feature, the engine's inlet air flow can be calculated through parameters such as the engine's physical speed.

[0038] Preferably, the specific calculation method of the engine inlet air flow is:

[0039] 1) Target temperature T before passing through the fan inlet t2_Dem The fan conversion speed n is calculated by measuring the physical speed n1 1r , the specific calculation formula is:

[0040]

[0041] 2) According to the working characteristics of the engine, the fan flow rate W is converted 2r and converted speed n 1r The corresponding relationship is used to calculate the fan conversion flow W 2r , the specific formula is:

[0042] W 2r =f(n 1r )

[0043] 3) By converting the flow rate W 2r , total pressure before fan P t1 and the target temperature before the fan inlet T t2 Dem calculates the fan's inlet air flow rate W2, the specific formula is:

[0044]

[0045] Among them, σ i2 is the total pressure recovery coefficient of the rear part of the inlet jet precooling device.

[0046] By adopting this method, the inlet air flow rate can be directly calculated without further measurement, and the calculation is accurate. At the same time, the number of measuring rakes is reduced as much as possible to avoid errors in measurement.

[0047] Step S300, initial cooling medium flow rate W c calculate;

[0048] According to the fan inlet air flow W2, the total temperature of the jet precooling device T t1and the target temperature before the fan inlet T t2 Dem calculates the initial cooling medium flow rate W c The specific formula is:

[0049] W c =f(W2,T t1 ,T t2 Dem)

[0050] Based on the parameters that have been measured or calculated in the previous steps, no additional measurement parameters are added, so that the accurate initial cooling medium flow rate W can be obtained. c .

[0051] Step S400: Calculate the actual cooling medium flow rate.

[0052] Some assumptions are introduced in the calculation of the initial cooling medium flow rate (target temperature before the fan inlet T t2_Dem ) and empirical relations (n 2r and W 2r The relationship between the fan and the fan may cause the temperature of the airflow in front of the fan to deviate from the target value T t2_Dem , which needs to be corrected.

[0053] Preferably, the actual cooling medium flow rate is calculated as follows:

[0054] 1) After the airflow passes through the fan, the water droplets in the air will further evaporate or attach to the wall, and the liquid water content in the air will be greatly reduced, that is, the total temperature after the fan T t13 The influence of water mist is small and the measurement accuracy is relatively high;

[0055] 2) According to the engine operating characteristics, the total pressure ratio of the fan can be calculated from the fan speed conversion: f and fan efficiency η f ;

[0056] 3) According to the total temperature T after the fan t13 , total pressure ratio π f and fan efficiency η f The actual total temperature T before the fan can be reconstructed t2c ;

[0057] 4) Using T t2c Correct the cooling medium flow rate to obtain the actual cooling medium flow rate, so that T t2c Closer to the target value T t2_Dem .

[0058] By using the total temperature after the fan, the fan pressure ratio and the fan efficiency to reconstruct the actual total temperature before the fan, the initial cooling medium flow rate can be corrected to obtain a more accurate cooling medium flow rate.

[0059] The present application utilizes the inherent working characteristics of the engine and the onboard test parameters of conventional engines, and calculates the total temperature, total pressure, inlet air flow and cooling medium flow through existing parameters or parameters that can be conveniently and accurately measured as much as possible. There is no need to consider temperature sensors, delays and measurement errors, and a more accurate calculation is made for the given initial water volume. The test parameters after the fan containing a smaller amount of liquid water are used to correct the water spray volume, thereby achieving the purpose of high-precision water control. At the same time, the number of rakes in the inlet duct can be minimized, and there is no need to consider the impact of the rake on the flow field, the structure of the rake itself, the test reliability and the installation space. The measurement parameters are few, the measurement is convenient, and the calculation results are accurate.

[0060] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A jet cooling control method for a jet pre-cooling engine, characterized in that: include: Obtain the aircraft's flight altitude H and flight speed Ma0, and calculate the total temperature T of the incoming flow from the jet precooling device. t1 and total pressure P t1 ; Get the target temperature T before the fan inlet t2_Dem Calculate the fan conversion speed n of the target fan 1r , according to the fan conversion speed n 1r And the converted flow rate W 2r The corresponding relationship is used to calculate the converted flow rate W of the fan. 2r , and further calculate the engine's inlet air flow rate W2; According to the fan inlet air flow W2, the total temperature T of the jet precooling device t1 and the target temperature before the fan inlet T t2_Dem Calculate the initial cooling medium flow rate W c ; Measure and obtain the total temperature T after the fan t13 , and obtain the total pressure ratio πf and fan efficiency η according to the engine operating characteristics f , reconstruct the actual total temperature T before the fan t2c , using the actual total temperature T before the fan t2c Initial cooling medium flow rate W c Make corrections to obtain the actual cooling medium flow rate.

2. The jet cooling control method for a jet pre-cooling engine according to claim 1, characterized in that: The total temperature T of the incoming flow of the jet precooling device t1 and total pressure P t1 The calculation formula is: Where, P0 is the ambient static pressure; T0 is the ambient static temperature; P t1 is the total pressure of the incoming flow from the jet precooling device; T t1 is the total temperature of the incoming air before the jet precooling device; Ma0 is the flight Mach number of the aircraft; k is the specific heat ratio of the incoming air; σ i1 is the total pressure recovery coefficient of the front part of the inlet jet precooling device.

3. The jet cooling control method for a jet pre-cooling engine according to claim 1, wherein: The fan conversion speed n 1r Target temperature before fan inlet T t2_Dem The engine inlet air flow rate W2 is calculated by the total pressure before the fan P t2 and target temperature T t2_Dem Calculated.

4. The jet cooling control method for a jet pre-cooling engine according to claim 3, characterized in that: The fan conversion speed n 1r The calculation formula is: The calculation formula of the inlet air flow rate W2 is: Among them, σ i2 is the total pressure recovery coefficient of the rear part of the inlet jet precooling device.

5. The jet cooling control method for a jet pre-cooling engine according to claim 1, characterized in that: The actual total temperature before the fan T t2c The calculation formula is:

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