Thermal And Flow Field Analysis Inside And Outside Of The Pneumtiac Duct System

Pneumatic duct system which is throughout important locations is a significant component ofaircraft environmental control system. The high temperature and pressure air which is transferredfrom the engine is conducted through the pneumatic duct, providing air source to anti-ice system ofthe engine and the airfoil、environmental control system of the passenger cabin、fuel tank and watertank pressurization system and so on. When the outside temperature of the ducts exceeds a certainvalue, it will not only influence the operating condition of duct system, but also increase thermal loadof neighboring equipments. Therefore thermal and flow calculation is the basis of design and optimizeof duct system. Boundary conditions such as flow rate, pressure drop, velocity and heat loss insideand outside of the duct are the premises and requirements of duct thermal and flow analysis. Howeverin our country the research of pneumatic duct is just started, a complete theoretical system andexperimental methods are not yet formed. This situation may have little assistance for independentlydevelopment of aircraft envirmental control system in our country, and is one of the key issues to besolved in the field of environmental control system design of large aircraft and fighter aircraft.For reasons above, heat and flow transfer analysis of the pneumatic duct is of great significance.Based on the research of working characteristics and operating conditions of the high temperaturepneumatic duct system, a computation model is developed by means of one dimension lumpedparameter technology based on the principle of bleed air system and fluid network algorithm, and thensystem steady state and transient analysis is proceeded to obtain thermal and flow behaviors such astemperature and pressure of nodal point. Afterwards numerical method is applied to solve the thermalconduction and convection problems inside the cabin, as well as investigate key parameters and theirinfluence factors by means of finite volume method, while the influencing factors such asaccerleration, position, diameter of the duct and insulation.on the temperature and flow distributionwere investigated.Finally fault state of the duct is preliminarilly simulated. This paper providesreference value for the combination property evaluation and reliability design of aircraft pneumaticduct system.