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RU-2861590-C1 - METHOD FOR THERMAL TESTING OF AIRCRAFT ELEMENTS

RU2861590C1RU 2861590 C1RU2861590 C1RU 2861590C1RU-2861590-C1

Abstract

FIELD: thermal testing. SUBSTANCE: invention relates to methods for reproducing aerodynamic thermal effects on aircraft elements (AE) under ground conditions. The method includes radiative heating of the AE on a thermal test bench using several heating panels with infrared heating, each with individual heating control by electric power, as well as continuous temperature measurement during the heating process outside and inside the AE. For temperature measurement, non-contact inertialess radiant heat flux sensors (RHFS) are used, which are installed in the space between the heating panel and the surface of the AE, providing direct measurement of the density of the radiant heat flux supplied to the AE and the surface temperature of the AE. EFFECT: increasing the accuracy of measuring the surface temperature of the AE and the value of the density of the radiant heat flux supplied to the AE during thermal testing, as well as simplifying the preparation process and reducing the test time. 3 cl, 3 dwg, 2 tbl

Inventors

  • Chasovskoi Evgenii Nikolaevich
  • Rusin Mikhail Iurevich
  • ANTONOV VLADIMIR VIKTOROVICH
  • Vorobev Sergei Borisovich
  • Lipatov Sergei Iurevich

Dates

Publication Date
20260506
Application Date
20250910

Claims (12)

  1. 1. A method for thermal testing of aircraft elements (AE), with a known degree of surface blackness outside and inside the AE, including radiant heating of the AE on a thermal stand using several infrared heating panels, each with individual heating control by electric power, as well as continuous temperature measurement during the heating process outside and inside the AE, characterized in that contactless inertialess radiant heat flux sensors (RHFS) are used for temperature measurement, which are installed in the space between the heating panel and the AE surface, providing direct measurement of the density of the radiant heat flux supplied to the AE and the surface temperature of the AE, wherein a paired version of the sensor is used, having two independent sensitive elements in a single protective casing, directed in opposite directions, which makes it possible to simultaneously measure the value of the density of the heat flux supplied to the AE and the value of the surface temperature of the AE, wherein the RHFS, installed in the center of each heating panel, is a heating control sensor, and for additional control in other two DLTPs are installed at points of the heating panel near the surface of the EL, at the edges of the heating panel, the heating is controlled by the value of the EL surface temperature corresponding to the temperature in a real flight for each heating zone, determined by calculation by solving the end-to-end and coupled problem of calculating the parameters of heat exchange of the EL with the boundary layer of the air flow and simultaneous calculation of temperature fields along the thickness and length of the EL, the heating temperature inside the EL is also controlled by paired DLTPs installed inside the EL along its axis opposite the heating control sensors of each heating panel, with the direction of their sensitive elements to the opposite sides of the inner wall of the EL, which makes it possible to control the heating inside the EL from its windward and leeward side, the actual heating temperature of the EL surface is measured by DLTPs, the sensitive elements of which are directed to the surface of the EL, and the actual value of the supplied heat flux (E sub ) to the surface of the EL at the points of installation of DLTPs, the sensitive elements of which are directed to the heating panel, is determined on the basis of Kirchhoff's law and in in accordance with the Stefan-Boltzmann law
  2. E under = σ * (T tp ) 4 ,
  3. where σ is the Stefan-Boltzmann constant, W/(m 2 *K 4 ),
  4. T tp - measured by the DLTP temperature of the heat flow, K,
  5. Moreover, when determining the actual values of the surface temperature and the value of the supplied heat flow (E sub ), it is necessary to take into account the correction for the value [1/(ε) ela ], where (ε) ela is the emissivity of the ELA surface.
  6. 2. The method of thermal testing of the ELAV according to paragraph 1, characterized in that the heating mode of the ELAV is carried out according to the value of the temperature of the boundary layer of air (T e ) at the surface of the ELAV, determined by calculation using the method of calculating the parameters of aerodynamic heat exchange on the surface of the ELAV in the supersonic flight mode for given: speed, flight altitude, angle of attack and shape of the surface of the ELAV, in the form of calculated values of the heat transfer coefficient and the temperature of the boundary layer of air (T e ) at the wall of the ELAV at each point, then the heating is controlled by the DLTP, the sensitive element of which is directed at the heating panel, and the value of the heating temperature is selected equal to the temperature (T e ) with a correction for the value of [1/(ε) ela ], where (ε) ela is the emissivity of the surface of the ELAV, and the actual heating temperature of the surface of the ELAV is controlled by all DLTPs directed at the surface of the ELAV.
  7. 3. The method of thermal testing of the ELAF according to paragraph 1, characterized in that the heating mode of the ELAF is carried out according to the value of the heat flux density supplied to the surface of the ELAF in a real supersonic flight, determined by calculation in the form of values of the heat flux density (E) in each zone of the ELAF for each moment of flight time, and the temperature for the heating control mode according to the DLTP, the sensitive element of which is directed at the heating panel, is determined from the Stefan-Boltzmann equation for the calculated value of the heat flux density (E) with a correction for the emissivity of the ELAF surface
  8. T tp = (1/ε ela ) * [E / σ] 1/4 ,
  9. where σ is the Stefan-Boltzmann constant, W/(m 2 *K 4 ),
  10. E is the specified calculated value of heat flux density, W/( m2 ),
  11. T tp is the operating temperature, K, of the heating system,
  12. (ε) ela - the emissivity of the ELA surface.

Description

The invention relates to the field of thermal testing, namely to methods for reproducing aerodynamic thermal effects on aircraft elements (hereinafter referred to as ELA) under ground conditions. Thermal rig tests are part of static testing of aircraft and are conducted to obtain data on the actual strength of aircraft under aerodynamic thermal loads, as close as possible to actual flight conditions. In practice, the most common method of heating the tested aircraft is radiation heating using quartz incandescent lamps. This allows for the easy reproduction of the desired temperature field at a high heating rate by varying the electrical voltage in the heaters using control devices. However, almost all existing thermal heating systems use the temperature measured by a thermocouple attached to the surface of the ELA to control the heating of the ELA. However, the errors in such thermocouple measurements are significant, especially during transient heating conditions, and are highly dependent on the conditions of the thermocouple's attachment to the ELA. Experiments have shown that the errors in ELA surface temperature measurement range from -150°C to +200°C. A method for setting thermal conditions is known (RU Patent No. 2451971, IPC G05D23/19, B64G7/00, G01N17/00, published 05/27/2012),during infrared heating, when a coating consisting of two components is applied to the outer surface of the ELA, the emissivity of one of which is more than twice the emissivity of the other, and the temperature for each heating zone at a constant heat flux density is set according to a calculation formula taking into account the emissivity of the surface in these zones. The disadvantages of this method include the fact that the method for setting thermal conditions, heating control is carried out according to the temperature on the surface of the EL, measured by thermocouples glued to the EL, and the use of coatings that change the emissivity of the surface of the EL unevenly, i.e., the design being tested does not correspond to the actual one and the errors in the magnitude of the supplied heat flux are quite significant, while there is no control over the magnitude of the supplied radiant heat flux during the testing process. A method of thermal testing is known (RU Patent No. 2775689, IPC G05D23/19, B64G7/00, G01N17/00, published 06.07.2022), whichincludes zone heating of the ELA surface with heaters made of quartz lamps with a reflective screen and temperature measurement in the ELA cross-sections with temperature sensors installed on a reflective screen made of a porous material and fixed to a rigid base; tubes are placed in the screen material and connected to a collector filled with water. The disadvantages of this method include its very low accuracy, as heating is controlled not by the temperature on the EL surface, but by thermocouples mounted on a reflective screen. This means that the heat flow directly to the EL is not measured or controlled. Another drawback is that the emissivity of the EL surface is not taken into account, although it is heated by radiation. The closest in technical essence is the method for controlling heating during thermal tests (RU Patent No. 2676385, IPC G01N 25/72 (2006.01); G01M 9/04 (2006.01), published 12/28/2018 Bulletin No. 1), in which the control and monitoring of radiative heating is carried out based on the value of the heat flux density or the radiative power of the heater created in each heating zone and equal to the heat flux density or the amount of heat supplied to the ELA in flight. The main disadvantage of the known method is the use of contact thermocouples to measure the surface temperature of the EL, as well as the use of contact thermocouples in the DTP, which greatly affects the accuracy of the tests. The technical result of the proposed invention consists in increasing the accuracy of measuring the surface temperature of the ELA and the value of the density of the radiant heat flux supplied to the ELA during thermal testing at any heating and cooling rates, due to direct and immediate measurement of the density of the radiant heat flux in a contactless manner. The specified technical result is achieved by the fact that it is proposed: 1. A method for thermal testing of aircraft elements (AE), with a known degree of surface blackness outside and inside the AE, including radiant heating of the AE on a thermal stand using several infrared heating panels, each with individual heating control by electric power, as well as continuous temperature measurement during the heating process outside and inside the AE, characterized in that contactless inertialess radiant heat flux sensors (RHFS) are used to measure the temperature, which are installed in the space between the heating panel and the AE surface, providing direct measurement of the density of the radiant heat flux supplied to the AE and the temperature of its surface, and a paired version of the sensor is used, havin