Parametric Effect Investigation on Aerodynamic Interaction Characteristics for Tandem Rotors in Forward Flight

摘要

An iterative free-wake computational method has been developed for the prediction of aerodynamic interactionrncharacteristics between the twin rotors of a tandem helicopter. In this method, the mutual interactionrneffects between twin rotors as well as the rotor and wake have been included, and a rotor wake model,rnblade aerodynamic model and rotor trim model have been coupled during the process of solution. A newrndual-rotor trim method has been presented to be suitable for the aerodynamic interaction calculations betweenrntandem twin rotors. By the present method, the blade aerodynamic loads and rotor performance on arntandem twin-rotor in the conditions of interactions have been calculated, and the comparisons with thernavailable experimental data have been also made to show the capability of the present method. Then, therneffects of such parameters as the longitudinal separation and axial separation between twin rotors on thernaerodynamic interaction characteristics have been systematically analyzed. As a result, the conclusionsrnwhich can be meaningful for guiding on structure layout of the tandem rotors have been obtained. Furthermore,rnthe rotor performance between the tandem rotors and a single rotor has been compared, and the calculatedrnresults indicate that the strongest interaction state does not appear in the hovering state, but in lowspeedrnforward flight state.