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Simulation of air cooling systems for onboard aviation radio electronic equipment

Keywords:

Yu. I. Luzhavin – Post-graduate Student, Head of Sector, JSC “POLYOT Research & Production Company”, Nizhny Novgorod. E-mail: luzhavin@rambler.ru
V. P. Khranilov – Dr.Sc. (Eng.), Professor of "Computer technologies in design and manufacturing" Department, Deputy Director, IRIT Nizhny Novgorod State Technical University n.a. R.E. Alekseev. E-mail: hranilov@nntu.nnov.ru


With the use of numerical analysis packages there emerged a possibility of detailed account of aerodynamic processes occurring in the radio electronic equipment. The most popular program of aerohydrodynamic analysis is SolidWorksFlowSimulation which is integrated in SolidWorks CAD software. Despite the fact that the forced air cooling in aircraft radio electronic equipment is most popular, the design and modeling methodology of air cooling systems using advanced aerodynamic analysis programs require careful analysis. The heat transfer from the heat load equipment to the environment is usually effected by means of central air cooling system. Supply of the cooling air from the cooling system to the tray of the frame is accomplished through a coupling union, then the cooling air enters the zone of the unit. The basis of the air cooling unit is a tray frame, which determines the distribution of airflow via an additional guide. At a flight altitude of up to 8 thousand meters the air conditioning system supports the nominal temperature of the supply air from the central air cooling system in the order of 5 ± 5° C. If the altitude is more than 8 thousand meters the air conditioning system solves the problem of moisture separation by reducing the supply air temperature to minus 40 ± 5° C; the supply air volume is reduced by 40% compared to nominal, at that. Also, in the mode of planning an airplane, other modes of onboard electronics cooling are possible. In some designs of radio electronic equipment with forced air cooling the entrainment of ambient air to the unit takes place due to reduced pressure zone in the tray of the frame. The calculations show that in some designs the heat transfer coefficient significantly changes with the change of the flight mode. Therefore, when the radio electronics thermal analysis is carried out, it is important to consider the change of the volume of the supply air depending on its temperature. Simulation of the cooling system in SolidWorksFlowSimulation program is possible when using both the internal and external tasks. In the development of computational models and the grid, one should consider the following indicators: possible duration of the calculation, assigned computing resources and an admissible error of calculation. At the initial stage of aerodynamic and thermal analysis, it is necessary to simplify the geometric model or create an equivalent one to reduce the time spent on the creation of the finite element grid and the calculation itself. To solve the math problem accurately enough, and to assess the accuracy attained, it is necessary to carry out several calculations using different rarer and more frequent computational grids for the purpose of determining the frequency of a computational grid, from which the solution of the problem ceases to depend significantly on the frequency of the grid. Using programs of aerohydrodynamic and thermal analysis allows efficient design of the air cooling system. This makes it possible to solve the problem of temperature stabilization in the radio electronic equipment, which in turn improves the reliability, weight and size and quality characteristics.
References:

  1. Alyamovskij A. A., Sobachkin A. A., Odinczov E. V. Solid Works 2007/2008. Komp'yuternoe modelirovanie v inzhenernoj praktike. Sankt-Peterburg: 2008.
  2. Belousov E. L., Ushkar M. N. Konstruirovanie blokov bortovoj aviaczionnoj apparatury' svyazi. N. Novgorod: NGTU. 2005.
  3. Shi D. Chislenny'e metody' v zadachax teploobmena: Per. s angl. M.: Mir. 1988.
  4. Luzhavin, Ju. I. Avtomatizirovanny'j metod modelirovaniya teplovogo rezhima pri proektirovanii aviaczionnoj bortovoj RE'A s prinuditel'noj sistemoj oxlazhdeniya v paketax SolidWorksSimulation i SolidWorksFloSimulation // Materialy' XVIII mezhdunar. nauch.-texn. konferenczii «Radiolokacziya, navigacziya, svyaz'». Voronezh: SEKVOEE. 2012. S. 78–83.

June 24, 2020
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