Numerical simulation method for occurrence of rainfall in aircraft flight

Abstract

The present invention relates to a numerical simulation method for the occurrence of rainfall in the aircraft flight. The method comprises: generating an aircraft flow field space calculation grid; determining flight conditions and rainfall conditions; solving air phase fluid aerodynamic performance data and air phase fluid wall shear stress; solving the local raindrop collection rate and the local raindrop impact mass flow on the surface of the aircraft; solving the increment of the raindrop impact coefficient; taking body-fitted grids on the airfoil surface in the aircraft flow field space calculation grid as surface water film control bodies, setting the air flow attach point, the air flow transition point and the air flow reattach point that are presented on the airfoil surface, and solving the water film thickness of all the surface water film control bodies successively; solving four parameters of the raindrop sputtering model; solving the equivalent water film surface roughness; updating the geometrical shape of the aircraft according to the water film thickness, and reconstructing the aircraft flow field space calculation grid; obtaining updated air phase fluid aerodynamic performance data; and obtaining the aerodynamic performance loss data of the aircraft caused by the rainfall.

Description

technical field [0001] The invention belongs to the application of computational fluid dynamics in the field of aeronautical engineering, in particular to a numerical simulation method when an aircraft encounters rainfall during flight. Background technique [0002] During the flight mission in the air, the aircraft often passes through the clouds and encounters possible rain. When flying in a rainy environment, the rain will collide with the surface of the aircraft to generate additional force and additional moment, and the rain will adhere to the surface of the aircraft to form a flowing water film, which not only increases the mass of the aircraft, but also changes the aerodynamic shape of the aircraft , affecting the air flow field characteristics of the aircraft, causing the loss of the aerodynamic performance of the aircraft, endangering the balance, stability, maneuverability and flight quality of the aircraft, and affecting flight safety. In addition, it cannot be i...

AI Technical Summary

Problems solved by technology

The rain film thickness calculation algorithm used in the numerical simulation method for studying the adverse effects of rainfall on the aerodynamic performance of the aircraft is based on the growth equation of the water film thickness in the time domain. Stable, the water film thickness tends to be stable; but this algorithm is greatly affected by numerical fluctuations, the calculation time is long, and the calculation stability is poor, especially affected by the time step, the calculation accuracy is low

In addition, the above-mentioned numerical simulation method for studying the adverse effects of rainfall on the aerodynamic performance of aircraft does not effectively consider the energy dissipation problem during raindrop splashing in the theoretical calculation used to solve the raindrop splashing module, resulting in a large difference between the theoretical value and the experimental value. However, the raindrop sputtering test data is very limited, and there is no reasonable expansion, which makes the calculation conditions of the raindrop sputtering module quite harsh, which will inevitably produce certain errors in the numerical simulation, resulting in inaccurate results

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