Modeling of settlement external thermal loadings to a spacecraft surface by means of infrared heaters
Strength and thermal conditions of flying vehicles
1. Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
2. Khrunichev State Research and Production Space Center, 18, Novozavodskaya St., Moscow, 121087, Russia
The article is devoted to the methodical approach for a choice of an optimum operating mode of the infrared simulator concerning the accuracy of modeling of an isotropic field of the radiant streams, which are let out in the direction of the examined object during the complex electrical tests in the heat vacuum camera. For this purpose it is necessary to provide the set temperature condition for an object at vacuum camera preparation stages and during the tests and, also, it is necessary to overcome the interval of environmental pressure, at which there is a possibility of electric breakdown of a gas interval. Achievement and maintenance of the demanded vacuum level (P≤10-3Ра) in the camera is connected to the need for maintenance enough low temperatures (less than 90K) on camera screens. In this regard there is a need to supply examined object by power offsetting its energy due to radiation of an external surface of elements and providing the demanded thermal mode. For realization of this approach to the solution to the considered task it is necessary to have the geometrical models of a thermostatically controlled surface of a product and the simulator, as well as the information about spectral and integrated radiation characteristics of elements of the object external surface and radiators of the simulator. Thus, the side modules of the simulator are located along forming surfaces of the circular cylinder coaxial with the vacuum camera, and face modules placed in the plane perpendicular to the camera axis and intended for thermostat control of bottom part of the examined object.
Methodical approach to optimization of the power operating mode of the simulator of external heat loads on the surface of spacecraft was implemented with the help of FORTRAN-oriented simulation program based on gradient methods for criterion functions minimization. The computational experiment was carried out for various levels of temperatures of thermostat control. Optimum values of the electric power brought to each module of the simulator are revealed and errors of reproduction of the demanded temperatures are defined.
Calculations showed that the infrared simulator without reflectors can provide a satisfactory thermostating of the most important external surfaces of the examined object during electrical tests in the conditions of modeling both of space vacuum and external thermal conditions in the range of temperatures [-10; 30] ° C for devices and the equipment without the use of bench heaters for internal heating.
Keywords:Simulator, optimization, heat load, spacecraft
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