Three-dimensional Dynamic Simulation Of Large Unmanned Aircraft Overall Thermal Environment

With the rapid development of modern science and technology and people change the concept of a future war, the world more and more attention to the development and research of unmanned aircraft. In terms of large-scale, long-endurance unmanned aerial vehicle, due to the slow flight speed, the outer surface by the high altitude cold air currents, for airborne electronic equipment to provide cooling channels at the same time, low temperature possible also to electronic equipment, fuel tank and fuel system to produce hazards. Conventional thermal analysis are primarily directed at aircraft environmental control equipment manned aircraft, airborne equipment thermal environment analysis and provide the desired skin temperature field goal infrared features, and long-endurance unmanned aerial vehicle in a large concern these problems at the same time, resolve the problem skin cold, fuel and fuel system faces.In this paper, a large unmanned aircraft thermal environment research background, by analyzing the inner drone, mechanism of heat transfer characteristics of the thermal environment under the common external role in establishing the flow field and structure coupled heat transfer model, under different conditions and structures to carry out multi-cabin body coupling system 3D transient thermal analysis of the engine compartment and cabin equipment under different boundary complex fluid-structure coupling effect of thermal heat transfer problems, the fuel consumption during the flight dynamics lead to heat sink heat transfer studies, the main contents include(1) Analysis method based on network equipment cabin multibody 3D transient thermal coupling system. Thermal network model for the different characteristics of the containment system and typical equipment cabin equipment, the establishment of multi-body coupling system and cabin equipment monomers. By the outer surface of the skin under different conditions, high-speed convection heat transfer coefficient distribution and the corresponding local adiabatic temperature as a floating third boundary condition, imported into Sinda/Fluint software functional relationship is established, within the implementation of the external thermal environment coupled conduct system three-dimensional unsteady conjugate heat transfer calculations. Analysis of the flight, computing aircraft cabin equipment, changes of equipment and the air temperature field to understand equipment heating, convection, conduction, radiation impact on the cabin thermal environment, and influence of the heat transfer effect. Obtaining high power density temperature characteristics and control factors of equipment, and heat transfer characteristics and thermal state of the skin and cabin systems impact on the cabin thermal environment.(2) Based on volume method of engine compartment complex three-dimensional shape of unsteady heat. The establishment of a complex structure within an aircraft engine compartment pneumatic convective heat flow calculation model, by the external thermal environment as the third category of floating thermal boundary conditions, to achieve internal and external thermal environment coupled, using ANSYS-CFX software for three-dimensional non-engine compartment Steady radiation- Convection heat transfer calculation, analysis of the main factors affecting the skin and the cabin structure temperatures.(3) Based on Thermal Network Dynamic Change fuel heat sink three-dimensional unsteady heat transfer. The establishment of a heat transfer calculation model during flight fuel consumption leads to dynamic heat sink, using a layered dynamic grid processing volume changes due to fuel consumption, using Sinda/Fluint software in the tank to calculate the three-dimensional unsteady conjugate heat transfer analysis The main factors of the fuel temperature.Through the establishment of large-scale three-dimensional dynamic model of unmanned aircraft overall thermal environment, the use of numerical simulation of the engine compartment and cabin equipment under different boundary complex fluid-structure coupling effect of thermal heat transfer problems, resulting in fuel consumption during the flight dynamics of heat transfer heat sink research problems for UAV development designed to provide a reference.