Numerical simulations of helicopter aerodynamic interactions among the main rotor,fuselage,engine inlets/outlets and slung loads of specific geometries have been conducted by very few researchers.In this work,the stea...Numerical simulations of helicopter aerodynamic interactions among the main rotor,fuselage,engine inlets/outlets and slung loads of specific geometries have been conducted by very few researchers.In this work,the steady-state compressible Reynolds-averaged navier-stokes equations are solved to study the aerodynamic interactions among helicopter rotor,fuselage,engine and body of revolution in three cases,namely MI-171V5,ROBIN and UH-60A.In the first case,the downwash flow provided by the rotor of the uniform actuator disc model induces a significant deflection of the airflow velocity.The vortex-shaped distribution and evolution are discussed in detail.The engine can effectively change the overall flow field.The asymmetry of the flow field is observed by using the non-uniform actuator disc model.Qualitative analysis of ROBIN and quantitative computation of UH-60A show a consistent accuracy of the rotating reference frame model for rotor.The blade tip vortex motion of UH-60A is simulated and its radial position prediction is compared to empirical formulas.While performing flow of UH-60A in hover,both the fuselage normal force and rotor lift decrease because of the impact of the body of revolution.展开更多
For studying ice accretion on aircraft and helicopter airfoils,a modified model of the mass and heat transfer on icing surface was first proposed based on the classical Messinger model.Then an approach for predicting ...For studying ice accretion on aircraft and helicopter airfoils,a modified model of the mass and heat transfer on icing surface was first proposed based on the classical Messinger model.Then an approach for predicting ice accretion on multi-element airfoils was set up through introducing the interpolation calculation of airflow field around the multi-element airfoils.Consid-ering the equivalent thermal power from anti-ice system,a method of the prediction of ice accretion under anti-ice situation was proposed.In order to study the prediction of ice accretion on helicopter rotor,a numerical simulation method combining the computational fluid dynamics (CFD) technique with helicopter aerodynamics theory was set up.The agreement between the results of numerical simulation and the experimental data indicates that the model and methods proposed in this paper are feasible and effective,and that they can lay the foundation of the research on the dynamics in icing condition and design of anti/de-ice system.展开更多
A conventional Fowler flap is designed to improve the take-off and landing performances of an aircraft. Because the flight states of general aviation aircraft vary significantly. A Fowler flap with a double-sliding tr...A conventional Fowler flap is designed to improve the take-off and landing performances of an aircraft. Because the flight states of general aviation aircraft vary significantly. A Fowler flap with a double-sliding track has been designed, which is ca- pable of changing airfoil camber while cruising and climbing as well as meeting low-speed performance requirements. The aerodynamic characteristics of the variable camber Fowler flap were studied by computational simulation, and cambering was found to be beneficial for improving the lift-to-drag ratio when the lift coefficient was larger than the critical value, below which decambering was more effective; this critical value differed somewhat under different conditions. Taking the mecha- nism into account, the take-off and landing configurations were optimized on the basis of the GA （W）-1 airfoil with a 30% chord Fowler flap. Compared with reference configuration, the maximum lift coefficient of optimized take-off configuration was increased by 6.6% as well as the stalling angle and the lift-to-drag ratio were increased by 1.3° and 7.58%, respectively. Moreover, the maximum lift coefficient of the optimized landing configuration was increased by 6.3%, and the stalling angle was increased by 1.1°; however, the nose-down pitching moment of both configurations increased. Similar results were at- rained on a general aviation aircraft wing/body combination nism was established in a computer-aided design system, achieved by the double-sliding track. A 3D model of the variable-camber Fowler flap driving mecha- and the results showed that all design configurations could be展开更多
文摘Numerical simulations of helicopter aerodynamic interactions among the main rotor,fuselage,engine inlets/outlets and slung loads of specific geometries have been conducted by very few researchers.In this work,the steady-state compressible Reynolds-averaged navier-stokes equations are solved to study the aerodynamic interactions among helicopter rotor,fuselage,engine and body of revolution in three cases,namely MI-171V5,ROBIN and UH-60A.In the first case,the downwash flow provided by the rotor of the uniform actuator disc model induces a significant deflection of the airflow velocity.The vortex-shaped distribution and evolution are discussed in detail.The engine can effectively change the overall flow field.The asymmetry of the flow field is observed by using the non-uniform actuator disc model.Qualitative analysis of ROBIN and quantitative computation of UH-60A show a consistent accuracy of the rotating reference frame model for rotor.The blade tip vortex motion of UH-60A is simulated and its radial position prediction is compared to empirical formulas.While performing flow of UH-60A in hover,both the fuselage normal force and rotor lift decrease because of the impact of the body of revolution.
基金supported by the Aeronautical Science Foundation of China (Grant No. 2009ZA51007)
文摘For studying ice accretion on aircraft and helicopter airfoils,a modified model of the mass and heat transfer on icing surface was first proposed based on the classical Messinger model.Then an approach for predicting ice accretion on multi-element airfoils was set up through introducing the interpolation calculation of airflow field around the multi-element airfoils.Consid-ering the equivalent thermal power from anti-ice system,a method of the prediction of ice accretion under anti-ice situation was proposed.In order to study the prediction of ice accretion on helicopter rotor,a numerical simulation method combining the computational fluid dynamics (CFD) technique with helicopter aerodynamics theory was set up.The agreement between the results of numerical simulation and the experimental data indicates that the model and methods proposed in this paper are feasible and effective,and that they can lay the foundation of the research on the dynamics in icing condition and design of anti/de-ice system.
文摘A conventional Fowler flap is designed to improve the take-off and landing performances of an aircraft. Because the flight states of general aviation aircraft vary significantly. A Fowler flap with a double-sliding track has been designed, which is ca- pable of changing airfoil camber while cruising and climbing as well as meeting low-speed performance requirements. The aerodynamic characteristics of the variable camber Fowler flap were studied by computational simulation, and cambering was found to be beneficial for improving the lift-to-drag ratio when the lift coefficient was larger than the critical value, below which decambering was more effective; this critical value differed somewhat under different conditions. Taking the mecha- nism into account, the take-off and landing configurations were optimized on the basis of the GA （W）-1 airfoil with a 30% chord Fowler flap. Compared with reference configuration, the maximum lift coefficient of optimized take-off configuration was increased by 6.6% as well as the stalling angle and the lift-to-drag ratio were increased by 1.3° and 7.58%, respectively. Moreover, the maximum lift coefficient of the optimized landing configuration was increased by 6.3%, and the stalling angle was increased by 1.1°; however, the nose-down pitching moment of both configurations increased. Similar results were at- rained on a general aviation aircraft wing/body combination nism was established in a computer-aided design system, achieved by the double-sliding track. A 3D model of the variable-camber Fowler flap driving mecha- and the results showed that all design configurations could be
