On The Calculation Methods Of Aerodynamic Force For The Airship Hull In Incompressible Flow

The fluid dynamic force for a moving body in the flow field has a great influence on the stability and manoeuverability of the body,such as the aerodynamic force for the airship and the hydrodynamic force for the submarine.Furthermore,the force will have impact on the establishment of mathematical model and the design of control sys-tem of the body.This paper focuses on the aerodynamic force for the airship hull in the incompressible flow field,and an expression of the force is derived.This expression not only can calculate the aerodynamic force for the airship hull in the inviscid and incompressible flow field,but also can calculate the force in the viscous and incom-pressible flow field.Furthermore,the expression can provide help for establishing the mathematical model of the airship and designing the control system of the airship.This paper mainly includes the following contents:1.A new expression of aerodynamic force for a body moving in the incompressible flow field is re-derived,this expression can not only be compatible with Lamb's aerody-namic force expression in inviscid flow field,but also be compatible with aerodynamic force expression in viscous flow field which can obtains from vortex dynamics theory,Examples are used to verify this kind of compatibility.Furthermore,the specific ex-pression of the impulse mentioned by Lamb in the potential flow theory is clearly given by the expression of aerodynamic force.2.The Panel-Method is introduced to calculate the aerodynamic force for a body moving in inviscid flow field.The program of Panel-Mehthod has been written and im-proved,so that the program can be used to obtain information of the inviscid flow field when airship hulls with different shapes are translating or rotating in the flow field,on this basis,the aerodynamic force,especially the aerodynamic coefficient,for the hull can be calculated.Furthermore,The rationality of the ellipsoid equivalent method pro-posed by Kirilin is also verified by the Panel-Method.At the same time,the influence of the position of origin of the hull coordinate system on the aerodynamic force for the hull body has been studied when the hull is rotating around the origin.The improved Panel-Method not only provides a powerful tool for calculating the aerodynamic force for hull in inviscid flow field,but also provides a reference for studying the aerodynamic force for hull in viscous flow.3.Basing on computational fluid dynamics(CFD)technology,the unsteady aero-dynaic force coefficient of airship hull in viscous and incompressible flow is analyzed with quasi-steady hypothesis,which provides a new idea for effectively estimating the unsteady aerodynamic coefficient of the airship hull.