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Investigation of thermal interactions between elements of propulsion system and selected parts of the airplane skin in small aircrafts

Łapka P., Seredyński M., Furmański P.

Archives of Thermodynamics

2018

Vol. 39, no 3

45--61

Development of new or upgrading of existing airplanes requires many different analyses, e.g., thermal, aerodynamical, structural, and safety. Similar studies were performed during re-design of two small aircrafts, which were equipped with new turboprop engines. In this paper thermo-fluid analyses of interactions of new propulsion systems with selected elements of airplane skin were carried out. Commercial software based numerical models were developed. Analyses of heat and fluid flow in the engine bay and nacelle of a single-engine airplane with a power unit in the front part of the fuselage were performed in the first stage. Subsequently, numerical simulations of thermal interactions between the hot exhaust gases, which leave the exhaust system close to the front landing gear, and the bottom part of the fuselage were investigated. Similar studies were carried out for the twin-engine airplane with power units mounted on the wings. In this case thermal interactions between the hot exhaust gases, which were flowing out below the wings, and the wing covers and flaps were studied. Simulations were carried out for different airplane configurations and operating conditions. The aim of these studies was to check if for the assumed airplane skin materials and the initially proposed airplane geometries, the cover destruction due to high temperature is likely. The results of the simulations were used to recommend some modifications of constructions of the considered airplanes.

Analytical and numerical model of transient heat transfer in a single tube row heat exchanger

Taler D.

Archives of Thermodynamics

2007

Vol. 28, no. 1

51-64

Cross-flow tubular heat exchangers are widely applied as condensers and evaporators in air conditioners and heat pumps or as air heaters in heating systems. There are analytical and numerical mathematical models of heat exchangers of that type to determine the steady state temperature distribution of fluids. In this paper the transient response of a single-row tubular cross-flow tube - and - fin heat exchanger is analyzed. Partial differential equations for both hot and cold fluid are solved by the Laplace transform method with numerical inversion and by the finite-difference (finite-volume) method. The transient response of one-row tube - and - fin heat exchanger due to step change of air temperature is calculated using both developed approaches. Good agreement between the analytical predictions (the Laplace transform method and analytical exact steady state solution) and the finite difference solution has been found. After eliminating the time, using the Laplace transform, a simpler system of partial equations is formed, which can be solved analytically. In view of the complex form of the achieved solutions, the inverse Laplace transform is obtained numerically by the method due to Crump improved by de Hoog. The solutions presented in the paper can be used to analyze the operation of heat exchangers in transient conditions and can find application in systems of automatic control or in the operation of heat exchangers.