Study Of Integrated Installation Aerodynamic Characteristics Of Helicopter/Turboshaft Engine

In the process of modern helicopter design and development, the integration performance studyof helicopter/turboshaft engine ranks in an important position. In order to study the engine mountedimpact and some typical state integrated aerodynamic performance, the ROBIN body is selected asthe base model and the CFD method is introduced.Firstly, the ROBIN fuselage and NACA0012airfoil are chosen to create the geometric model. Toverify the feasibility of the moving reference frame, an isolated NACA0012rotor example iscalculated whose solutions are comparatible with the experimental datas. Then the flow field ofbody/rotor model is calculated and analyzed preliminary. A turboshaft engine design point calculationprogram is written to establish performance parameters at design point. Based on these parameters,the flow path design of engine intake and exhaust pipe are completed.Secondly, this research analyses the influence of the engine mounted and the installation positionon the condition of hovering and cruising. The results show: the installation of the engine causespressure drop near the inlet region, resulting increased lift and drag of the fuselage. Because ofingesting the rotor downwash flow, inlet total pressure distortion DC60under hovering state is muchhigher than that under cruising. Subject to the flow mixing effect, the nozzle total pressure losscoefficient in the condition of cruising goes up higher than that in hovering. The affect of engineinstallation position on the helicopter integration flow exhibits even more complex characteristics:each variation of the fuselage aerodynamic performance parameters in hovering and cruising presentsinconsistent with the mounting position change. When in a fixed flight condition, the aerodynamicperformance parameter changes are not monotonic with the installation position alters.Thirdly, the integrated flowfield under the sideslip states are investigated. The results show:sideslip condition will cause the fuselage to produce low-pressure zone on the lower surface offuselage and the nose of the fuselage on leeward side, while high-pressure on nose of fuselage onwindward side. High pressure area on the nose will spread to the downstream with the side slip angleincreases. So as the slip angle increases for0degree to60degree: the fuselage lift falls, the lateralforce increases, the fuselage drag goes up first and then turns to decline; around the inlet on theleeward, vortex will be generated where the flow sucked into. As a result, the inlet total pressure losscoefficient and total pressure distortion DC60are increased evidently; windward side of the engine nozzle is highly affected by the incoming flow, resulting nozzle total pressure loss coefficient andstatic pressure rise.Finally, this paper studies the impact of one side engine failure. The results show: the flow fieldpresent unsymmetries on the two sides of the fuselage when one side of engines doesn’t work,resulting in the magnitude of the fuselage side force, roll torque and yaw torque increase.