The auto-adjustable damping method for solving nonlinear heat transfer problems in flame tube of gas turbine aeroengine

摘要

The wall temperature distribution of the flame tube of the gas turbine aeroengine is considerably affected by the combustion, radiation and flow. Heat transfers to the wall by the flow convection and the radiation of the gas. When the cooling film is used, the heat flux by radiation heat transfer to the wall is against that by convection. The heat capacity of the flame tube structure is limited because the wall thickness is very thin. The interaction of these factors forms a conjugate system withstrong nonlinearity. For this strongly nonlinear problem, divergence or very slow convergence of the solution in the iterative process of the numerical calculation occur easily by using Newton's method and its variants (with relaxation and/or dampingfactor) due to the numerical instability. The auto-adjustable damping method has been developed to solve this problem. This is a farther improved variant of Newton‘s methods. The values of damping factors can be automatically adjusted continually duringthe iterative process in accordance with the judgement and adjustment to ensure the numerical stability. An effective convergence coefficient and a quickening coefficient are employed for releasing the requirement to the initial values and shortening theiterative process. By using a 3dimensional numerical calculation computer program, the wall temperature distribution of the flame tube of a gas turbine aeroengine has been obtained.