A helicopter ground joint test engine cabin temperature field measuring device

Abstract

The present application belongs to the technical field of helicopter test, and discloses a kind of engine cabin temperature field measuring device for helicopter ground combined test, first, the heat flow field of helicopter engine is calculated, then according to the heat flow field theoretical calculation result, three profiles representing the heat flow field distribution of engine are selected from front to back, and a plurality of temperature sensor mounting points are arranged respectively, temperature sensors are installed on each temperature sensor mounting point, and are connected to temperature collection device, after temperature sensor sends temperature signal to temperature collection device, temperature collection device sends temperature signal to server. The present application uses contact temperature measurement technology to measure the heat flow field temperature, realizes the engine cabin temperature field measurement of helicopter ground combined test bench, the measurement principle is simple and practical, not easy to be disturbed, the maintenance cost is lower, can display temperature data in real time, provides data basis for the function optimization of engine cabin heat flow field distribution and engine cabin inlet and exhaust system under various working conditions.

Description

Technical Field

[0001] This invention belongs to the field of helicopter testing technology and relates to a temperature measurement device for helicopter ground testing, specifically a temperature field measurement device for engine compartment of a helicopter ground joint test. Background Technology

[0002] As the power source of a helicopter, the temperature field distribution and variation process of the engine compartment are important performance indicators for helicopter flight and ground testing. The temperature field measurement results are related to the detailed design and functional optimization of the engine compartment's intake and exhaust systems, and are of great significance for verifying simulation results and analyzing data on the engine compartment's thermal flow field distribution under various operating conditions.

[0003] In the complex temperature field environment of helicopter ground joint tests, real-time safety monitoring of temperature changes in the thermal flow field within the engine nacelle is required. Currently, the main method for measuring thermal flow field temperature is non-contact temperature measurement technology, represented by thermal imaging. However, this technology is easily affected by the temperature of components other than the engine during helicopter ground joint tests. Contact temperature measurement technology mainly uses temperature sensors, crystals, and temperature-indicating paint. While its operating principle is simple and the temperature data is highly reliable, its application in engine nacelle temperature field measurement suffers from problems such as flow field vibration, incomplete temperature measurement, and difficulty in remote dynamic monitoring. Summary of the Invention

[0004] The purpose of this invention is to solve the above problems. This invention provides a temperature field measurement device for the engine compartment of a helicopter ground joint test. Based on the engine flow field calculation results, three profiles are selected, and a distributed temperature sensor arrangement is used. The output voltage signal is sent to the ground temperature acquisition device in real time and then transmitted to the data acquisition software in the server computer for real-time temperature display.

[0005] The technical solution of this invention:

[0006] A temperature field measurement device for the engine nacelle of a helicopter in a ground-based joint test includes the following steps:

[0007] Step 1: Perform theoretical calculations of the thermal flow field of the helicopter engine. Based on the actual components and dimensions of the upgraded engine, the theoretical calculation results of the thermal flow field of the helicopter engine nacelle are obtained using the CFD method.

[0008] Step 2: Based on the calculation results of the thermal flow field theory, three profiles representing the distribution of the engine's thermal flow field from the front end to the rear end, from low temperature to high temperature, are selected, namely the first profile, the second profile, and the third profile.

[0009] Step 3: In the first section, there is one temperature sensor installation point; in the second section, at least two temperature sensor installation points are arranged at equal intervals; and in the third section, at least three temperature sensor installation points are arranged at equal intervals.

[0010] Step 4: Install the temperature sensor at each temperature sensor mounting point and connect each to the temperature acquisition device;

[0011] Step 5: After the temperature sensor sends the temperature signal to the temperature acquisition device, the temperature acquisition device sends the temperature signal to the server.

[0012] Furthermore, in step one, the theoretical calculation of the thermal flow field of the helicopter engine specifically involves:

[0013] The first step is to create a three-dimensional model of the helicopter according to its actual dimensions, including components such as rotor, engine, ejector tube, and fairing;

[0014] The second step is to apply the CFD method to divide the computational region of the power cabin into grids based on the aerodynamic characteristics of the helicopter under working conditions. These grids are: a rotor sub-region for defining rotor motion, a power cabin sub-region for calculating the internal flow field of the power cabin, and a far-field sub-region for connecting the two regions and setting flight parameters.

[0015] The third step is to select a compressible gas as the fluid medium, and then select a Realizable gas based on the turbulent flow within the power compartment. -ε The turbulence model selects the Discete Ordinates thermal radiation model based on the radiative heat dissipation of the engine's outer surface, and sets the far-field incoming flow velocity and atmospheric pressure according to flight parameters, and sets the radiative heat dissipation coefficient and exhaust flow density according to engine parameters.

[0016] The fourth step is to select a density-based unsteady solution model for calculation to obtain the theoretical calculation results of the engine compartment thermal flow field.

[0017] Furthermore, in step two, the first profile is the front profile through which the airflow passes, specifically the compressor profile, which is a low-temperature profile. Based on the theoretical calculation results of the engine compartment thermal flow field, the profile in the flow field whose temperature is not affected by the rear end is selected, specifically close to the engine compartment fairing air inlet.

[0018] Furthermore, in step two, the second profile is the middle section through which the airflow passes, specifically the combustion chamber profile, which is a medium-high temperature profile, corresponding to the location of the combustion chamber.

[0019] Furthermore, in step two, the third profile is the rear profile through which the airflow passes, specifically the tail nozzle profile, which is the profile with the highest thermal flow field temperature in the theoretical calculation results of the engine compartment thermal flow field.

[0020] Furthermore, in step three, a temperature sensor mounting point is arranged 30mm below the air inlet of the fairing on the first section, three temperature sensor mounting points are arranged at 400mm intervals on the second section, and six temperature sensor mounting points are arranged at 200mm intervals on the third section.

[0021] Furthermore, the temperature sensor is a button-type armored thermistor temperature sensor. The thermistor is entirely encapsulated inside the button. A constant current source is applied to the two ends of the thermistor to excite it. The voltage across the resistor is measured, and the temperature data is obtained based on the voltage-temperature correspondence.

[0022] Furthermore, in step four, the method for installing the temperature sensor in the smooth composite surface is as follows:

[0023] The first step is to clean the surface of the temperature sensor and the surface of the shroud at the mounting location with alcohol to ensure that the contact surfaces are free of dust and oil stains.

[0024] The second step is to apply masking tape to the cleaned area to outline the 20mm*20mm sensor installation area;

[0025] The third step involves using quick-drying adhesive to attach the sensor to the surface of the fairing for initial fixation on the smooth composite curved surface. Then, apply 704 high-temperature resistant silicone rubber evenly around the sensor and let it stand for 24 hours to cure.

[0026] Furthermore, a method for mounting a temperature sensor on a large-particle rough surface that increases friction is as follows:

[0027] The first step is to clean the surface of the temperature sensor and the surface of the shroud at the mounting location with alcohol to ensure that the contact surfaces are free of dust and oil stains.

[0028] The second step is to apply masking tape to the cleaned area to outline the 20mm*20mm sensor installation area;

[0029] The third step is to first apply a layer of 704 high-temperature resistant silicone rubber to the rough surface with large particles, fill the rough surface, and let the surface cure for 1 hour until the surface is initially hardened. Then, apply a layer of 704 high-temperature resistant silicone rubber to the contact surface between the sensor and the rectifier, and stick it to the surface of the rectifier. Apply 704 high-temperature resistant silicone rubber evenly around the sensor, and use masking tape to fix it in a cross pattern. After two hours, when the 704 high-temperature resistant silicone rubber has initially cured, peel off the masking tape and let it stand for 24 hours to cure.

[0030] Furthermore, the above steps also include a fourth step: the temperature sensor test cable is fixedly attached to the engine compartment fairing using aluminum foil tape, and then gathered at the front of the engine compartment. It is fixed to the connecting rod of the locking mechanism on the lower side of the fairing, and after passing through the test hole of the engine compartment's front firewall, it is connected to the ground temperature acquisition equipment through the onboard wiring channel. During the wiring of the temperature test cable, high-temperature areas are avoided. When the cable harness is gathered and fixed to the connecting rod of the locking mechanism on the lower side of the fairing, sufficient extension length is left for the fairing to open and close. In the first 100mm length of the cable harness before gathering and fixing, silicone rubber is spread flat to fix the temperature test cable.

[0031] The beneficial effects of this invention are:

[0032] 1. This invention uses contact temperature measurement technology to measure the temperature of the thermal flow field, thereby realizing the measurement of the temperature field of the engine compartment of a helicopter ground joint test bench.

[0033] 2. The measurement principle of this invention is simple and practical, not easily interfered with, and has low maintenance costs. It can display temperature data in real time and review and compare temperature data throughout the entire process, providing a data basis for the distribution of thermal flow field in the engine compartment under various operating conditions and the functional optimization of the engine compartment intake and exhaust systems.

[0034] 3. The measuring device of the present invention is stable and reliable and can be used repeatedly for a long time. Attached Figure Description

[0035] Figure 1 This is a schematic cross-sectional view of the temperature field in the helicopter engine nacelle according to the present invention;

[0036] Figure 2 This is a diagram showing the arrangement of temperature sensors in a cross-section of the compressor.

[0037] Figure 3 Temperature sensor arrangement diagram of combustion chamber cross section

[0038] Figure 4 Diagram showing the arrangement of temperature sensors in the tailpipe cross-section

[0039] Figure 5 A schematic diagram of a sensor armor design model;

[0040] Figure 6 This is a block diagram of the temperature acquisition device.

[0041] Among them, 1 to 10 are the 10 temperature sensor installation points, i.e., measurement points, of the embodiment; 11 is the compressor cross-section; 12 is the combustion chamber cross-section; 13 is the tail nozzle cross-section; and 14 is the connecting rod of the lower locking mechanism of the fairing. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0043] This invention provides a temperature field measurement device for the engine nacelle of a helicopter ground-based joint test bench, comprising multiple PT100 temperature sensors, ground temperature acquisition equipment, and server computer data acquisition software. The technical solution mainly includes the following steps:

[0044] Theoretical calculation of the thermal flow field. When analyzing the thermal flow field distribution in a helicopter engine nacelle, it is necessary to consider not only the influence of the intake and exhaust airflows during helicopter operation, but also the influence of the rotor downwash airflow. First, a three-dimensional model is established according to the actual dimensions of the helicopter, including components such as the rotor, engine, ejector, and fairing. Computational fluid dynamics (CFD) is applied to divide the computational region of the engine nacelle into meshes based on the aerodynamic characteristics of the helicopter during operation. These meshes are: a rotor sub-region defining rotor motion, a engine nacelle sub-region calculating the internal flow field, and a far-field sub-region connecting the two regions and setting flight parameters. Compressible gas is selected as the fluid medium, and RealizableK is chosen based on the turbulent flow within the engine nacelle. -ε A turbulence model was used, selecting the Discete Ordinates thermal radiation model based on the radiative heat dissipation of the engine's outer surface. The far-field incoming flow velocity and atmospheric pressure were set according to flight parameters, and the radiative heat dissipation coefficient and exhaust flow density were set according to engine parameters. A density-based unsteady solution model was selected for calculation, yielding theoretical calculation results of the engine nacelle thermal flow field. The results show that air from the external environment enters the engine nacelle through the engine nacelle cowling inlet, flows through the high-temperature zone of the combustion chamber, and exits through the engine nacelle ejector tubes. This airflow carries away heat from the engine nacelle, ensuring that the maximum surface temperature of components near the engine reaches a reasonable level.

[0045] Decomposition of the measuring point profile. For example... Figure 1 As shown, during engine operation, high-temperature, high-pressure gas generated by combustion in the engine combustion chamber is ejected from the tailpipe and enters the ejector. Under the influence of the negative pressure airflow in the tailpipe, ambient temperature gas is drawn in from the engine compartment intake. This gas flows through sections 11, 12, and 13 and exits from the ejector, simultaneously carrying away the high-temperature gas radiated from inside the engine compartment. Based on theoretical calculations of the engine compartment thermal flow field, this patent uses the combustion chamber as a dividing section, dividing the engine compartment into compressor section 11, combustion chamber section 12, and tailpipe section 13 as engine compartment temperature field measurement sections. Section 11 is a low-temperature section, selected based on the aforementioned results, where the temperature in the flow field is not affected by the rear end. Specifically, it is located near the engine compartment fairing intake, allowing for analysis of the intake temperature distribution. Section 12 is the combustion chamber section, corresponding to the location of the combustion chamber, enabling analysis of the radiated temperature in the high-temperature zone. Section 13 is taken from the point with the highest flow field temperature in the aforementioned results; this is a crucial section, enabling analysis of the radiated temperature in the high-temperature exhaust zone.

[0046] Sensor Placement Method. The compressor section 11 of the power compartment is a low-temperature region. Based on the simulation analysis of the power compartment temperature field, the temperature in this section is low and the temperature field distribution is basically uniform. Therefore, a temperature sensor (measuring point 1) is selected to be installed 30mm below the fairing inlet as the temperature characteristic measuring point for this section. Figure 2As shown. Three temperature sensors (measuring points 2, 3, and 4) are installed at equal intervals of 400 mm along the combustion chamber profile 12 as characteristic measuring points for this profile. Figure 3 As shown. Section 13 of the tailpipe is a critical section. Due to the complex flow field here, the temperature field distribution is extremely uneven. Therefore, six temperature sensors (measuring points 5, 6, 7, 8, 9, and 10) are installed at equal intervals of 200 mm inside the fairing corresponding to this section as characteristic measuring points for this section. Figure 4 As shown.

[0047] like Figure 5 As shown, this is the sensor and its armor design. The power compartment environment is extremely harsh, with high-temperature radiation and electromagnetic interference from the strong current of the motor. High-temperature radiation is unavoidable, so it's necessary to reduce the strong electromagnetic interference from the motor. A PT100 platinum resistance temperature sensor was selected as the sensing element. Its measurement principle involves applying a constant current source to the thermistor, measuring the voltage across the resistor, and obtaining the temperature data based on the voltage-temperature relationship. Within the 0-450℃ range, its testing accuracy can reach 0.2℃, and it also has the advantage of strong resistance to electromagnetic interference. A button-type armor structure is used, encapsulating the platinum resistance entirely inside the button, improving the sensor's vibration resistance and allowing for a tighter attachment to the inner surface of the fairing, facilitating installation.

[0048] Temperature sensor installation process design. The internal surface of the fairing has two structures: a smooth composite curved surface and a rough surface with large particles to increase friction. The installation process is as follows:

[0049] 1. Clean the surface of the temperature sensor and the surface of the shroud at the mounting location with 95% alcohol to ensure that the contact surfaces are free of dust and oil stains;

[0050] 2. After cleaning, apply masking tape to the area to outline the 20mm*20mm sensor installation area;

[0051] 3. For smooth composite curved surfaces, use CN glue (such as 509 glue or other fast-drying glue) to attach the sensor to the surface of the rectifier for initial fixation. Apply 704 high-temperature resistant silicone rubber evenly around the sensor and let it stand for 24 hours to cure.

[0052] 4. For large, rough surfaces, first apply a layer of 704 high-temperature resistant silicone rubber to fill the rough surface and allow it to cure for 1 hour until it is initially hardened. Then, apply a layer of 704 high-temperature resistant silicone rubber to the contact surface between the sensor and the rectifier and attach it to the rectifier surface. Apply 704 high-temperature resistant silicone rubber evenly around the sensor and use masking tape to fix it in a cross pattern. After two hours, when the 704 high-temperature resistant silicone rubber has initially cured, remove the masking tape and let it stand for 24 hours to cure.

[0053] The temperature sensor test cable is fixed to the engine compartment fairing using aluminum foil tape and gathered at the front of the engine compartment. It is then secured to the lower locking mechanism linkage 14 of the fairing and passes through the test port of the engine compartment's forward firewall before connecting to the ground temperature acquisition equipment via the onboard wiring channel. High-temperature areas are avoided during the cable routing process. When the cable harness is gathered and secured to the lower locking mechanism linkage 14 of the fairing, sufficient extension length is allowed for the fairing's opening and closing. Silicone rubber is applied to the first 100mm of the cable harness before it is gathered and secured to maintain its position.

[0054] Design a temperature acquisition device. The ground-based temperature acquisition equipment is connected to the server computer via a network cable, communicating over Ethernet. The voltage signal from the PT100 temperature sensor is filtered, converted to digital value by an A / D converter, and then output as a digital temperature signal. This data is then displayed in real-time on the data acquisition software, which also provides full-process temperature data review and comparative analysis capabilities. The principle block diagram of the temperature acquisition device is shown below. Figure 6 As shown.

[0055] The above description is merely a specific embodiment of the present invention, providing a detailed description of the invention. Parts not covered herein are conventional techniques. However, the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A temperature field measurement device for the engine nacelle during a helicopter ground joint test, characterized in that, Includes the following steps: Step 1: Perform theoretical calculations of the thermal flow field of the helicopter engine. Based on the actual components and dimensions of the upgraded engine, the theoretical calculation results of the thermal flow field of the helicopter engine nacelle are obtained using the CFD method. Step 2: Based on the calculation results of the thermal flow field theory, three profiles representing the distribution of the engine's thermal flow field from the front end to the rear end, from low temperature to high temperature, are selected, namely the first profile, the second profile, and the third profile. Step 3: In the first section, there is one temperature sensor installation point; in the second section, at least two temperature sensor installation points are arranged at equal intervals; and in the third section, at least three temperature sensor installation points are arranged at equal intervals. Step 4: Install the temperature sensor at each temperature sensor mounting point and connect each to the temperature acquisition device; Step 5: After the temperature sensor sends the temperature signal to the temperature acquisition device, the temperature acquisition device sends the temperature signal to the server. In step two, the first profile is the front profile through which the airflow passes, specifically the compressor profile, which is a low-temperature profile. Based on the theoretical calculation results of the engine compartment thermal flow field, the profile in the flow field whose temperature is not affected by the rear end is selected, specifically close to the engine compartment fairing air inlet. In step two, the second profile is the middle section through which the airflow passes, specifically the combustion chamber profile, which is a medium-high temperature profile, corresponding to the location of the combustion chamber; In step two, the third profile is the rear profile through which the airflow passes, specifically the tail nozzle profile, which is the profile with the highest thermal flow field temperature in the theoretical calculation results of the engine compartment thermal flow field. In step three, a temperature sensor mounting point is arranged 30mm below the air inlet of the fairing on the first section, three temperature sensor mounting points are arranged at 400mm intervals on the second section, and six temperature sensor mounting points are arranged at 200mm intervals on the third section.

2. The helicopter ground joint test engine nacelle temperature field measurement device according to claim 1, characterized in that, In step one, the theoretical calculation of the thermal flow field of the helicopter engine is specifically as follows: The first step is to create a three-dimensional model of the helicopter according to its actual dimensions, including components such as rotor, engine, ejector tube, and fairing; The second step is to apply the CFD method to divide the computational region of the power cabin into grids based on the aerodynamic characteristics of the helicopter under working conditions. These grids are: a rotor sub-region for defining rotor motion, a power cabin sub-region for calculating the internal flow field of the power cabin, and a far-field sub-region for connecting the two regions and setting flight parameters. The third step is to select compressible gas as the fluid medium, select the Realizable k−ɛ turbulence model based on the turbulent flow in the engine compartment, select the Discete Ordinates thermal radiation model based on the radiative heat dissipation of the engine's outer surface, and set the far-field incoming flow velocity and atmospheric pressure according to the flight parameters, and set the radiative heat dissipation coefficient and exhaust flow density according to the engine parameters. The fourth step is to select a density-based unsteady solution model for calculation to obtain the theoretical calculation results of the engine compartment thermal flow field.

3. The method for measuring the temperature field of the engine nacelle in a helicopter ground joint test according to claim 1, characterized in that, The temperature sensor is a button-type armored thermistor temperature sensor. The thermistor is completely encapsulated inside the button. A constant current source is applied to the two ends of the thermistor to excite it. The voltage across the resistor is measured, and the temperature data is obtained based on the voltage-temperature relationship.

4. The method for measuring the temperature field of the engine nacelle in a helicopter ground joint test according to claim 1, characterized in that, In step four, the method for installing the temperature sensor in the smooth composite surface is as follows: The first step is to clean the surface of the temperature sensor and the surface of the shroud at the mounting location with alcohol to ensure that the contact surfaces are free of dust and oil stains. The second step is to apply masking tape to the cleaned area to outline the 20mm*20mm sensor installation area; The third step involves using quick-drying adhesive to attach the sensor to the surface of the fairing for initial fixation on the smooth composite curved surface. Then, apply 704 high-temperature resistant silicone rubber evenly around the sensor and let it stand for 24 hours to cure.

5. The method for measuring the temperature field of the engine nacelle in a helicopter ground joint test according to claim 1, characterized in that, The method for mounting a temperature sensor on a rough surface with large particles that increase friction is as follows: The first step is to clean the surface of the temperature sensor and the surface of the shroud at the mounting location with alcohol to ensure that the contact surfaces are free of dust and oil stains. The second step is to apply masking tape to the cleaned area to outline the 20mm*20mm sensor installation area; The third step is to first apply a layer of 704 high-temperature resistant silicone rubber to the rough surface with large particles, fill the rough surface, and let the surface cure for 1 hour until the surface is initially hardened. Then, apply a layer of 704 high-temperature resistant silicone rubber to the contact surface between the sensor and the rectifier, and stick it to the surface of the rectifier. Apply 704 high-temperature resistant silicone rubber evenly around the sensor, and use masking tape to fix it in a cross pattern. After two hours, when the 704 high-temperature resistant silicone rubber has initially cured, peel off the masking tape and let it stand for 24 hours to cure.

6. A method for measuring the temperature field of an engine nacelle during a helicopter ground joint test, as described in claim 4 or 5, characterized in that, The method of installing the temperature sensor also includes a fourth step: the temperature sensor test cable is fixedly attached to the engine compartment fairing with aluminum foil tape, and then gathered at the front of the engine compartment. It is fixed to the locking mechanism linkage on the lower side of the fairing, and then connected to the ground temperature acquisition equipment through the test hole of the engine compartment front firewall via the on-board wiring channel. During the wiring of the temperature test cable, avoid high-temperature areas. When the cable harness is gathered and fixed to the locking mechanism linkage on the lower side of the rectifier, leave enough extension length for the opening and closing of the rectifier. Apply silicone rubber to a 100mm length before gathering and fixing the cable harness to secure it.

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