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For the situation that the pitching moment of a civil fuselage-mounted aircraft shows to pitch up, the paper studied a new type of improvement measures-to truncate the inner slat. The numerical simulation method was used to study the aerodynamic characteristics of the basic landing configuration and the improvement configuration. The flow characteristics of the two configurations under the high angle of attack are given, and the flow mechanism of the improvement measures is analyzed. The influence of the improvement measures on the intake of the engine is also evaluated. The results show that: the low-speed pitching moment shape depends on the separation position of the wing; separation from the inside wing makes the aircraft "rise"; separation from the outer wing makes the aircraft "head",and separation from the inside wing makes the aircraft "bow"; the pitching moment provided by the horizontal tail determines the total pitching moment; the main reason for the aircraft "bow" is that the separation from the inside wing reduces the downwash of the horizontal tail from the wing; the improvement measures do not affect the engine intake of the fuselage-mounted aircraft when the angle of attack is not greater than the stall angle of attack.the improvement measures do not affect the engine intake of the fuselage-mounted aircraft when the angle of attack is not greater than the stall angle of attack.the improvement measures do not affect the engine intake of the fuselage-mounted aircraft when the angle of attack is not greater than the stall angle of attack. [ABSTRACT FROM AUTHOR]

Eddy viscosity models have been widely used in many engineering applications of turbulence. Usually there are additional source terms on the right side of the turbulent governing equations, which may play an important role in the computation of Navier-Stokes equations. Stiffness that results from source terms is analyzed in details and the significant balance between production term and destruction term is discussed, together with point implicit approach, an universal way to solve equations with source terms. Afterwards both S-A turbulence model with weak stiffness and k-w SST turbulence model with strong one are taken as examples to show the specific treatments concerning about the different source terms between these two. The paper ends with numerical tests of RAE 2822 airfoil transonic flow, which demonstrates that the methods above can overcome the stiffness from the source terms and improve the stability of the computation effectively. [ABSTRACT FROM AUTHOR]

The hot air anti-icing system is one of the important ways to prevent aircraft icing. Numerical simulation method was carried out to study the influence of the structural parameters on the thermal performance of the hot air anti-icing system. The hot air flow and heat transfer in the anti-icing cavities with different nozzle-to-surface height, number of the nozzle rows and hot air jet angle were simulated using the computational fluid dynamics (CFD) method. The thermal efficiency of the anti-icing system and the convective heat transfer coefficient distribution of the skin inner surface were obtained. The results show that; 1) with the increase of the nozzle-to-surface height in the range of 4mm to 36mm, the thermal efficiency of the anti-icing system reduces and the heat transfer performance of the hot air impinging on the surface weakens, 2) with consistent flow flux, the thermal efficiency of the anti-icing system increases from three to two nozzle rows, 3) the thermal efficiency improves with the 15° rotation of the hot air jet angle along the upper surface direction, indicating that the surface curvature effects the jet surface heat transfer performance. The results presented in this paper can help to the design of the anti-icing cavity. [ABSTRACT FROM AUTHOR]