3D Laser-Doppler-Velocimeter, Measurements within the HART-Test Program

Abstract

3D Laser-Doppler-velocimeter measurements within the HART test campaign on a helicopter model rotor of a BO 105 were performed in the open test section of the DNW from 15.6.94 - 20.6.94. The aim of these measurements was the datermination of the instantaneous velocity field of the blade tip vortex on the advancing side of the model rotor immediately before interaction with the blade took place at an azimuth angle of &#61 48. From these data the information on the vortex core size, blade-vortex missdistance, vorticity distribution and circulation distribution was obtained. This particular vortex position was chosen with respect to the intensive blade-vortex interaction (BVI) which occurs at &#61 48 in the case of the 6 decent flight condition. Three baseline cases without Higher Harmonic Control (HHC) and two cases special HHC settings for low noise and low vibration. Especially for this purpose in the DLR Institute for Fluid Mechanics in Goettingen a new three component laser-Doppler-Velocimeter (3D LDV) with a working distance of 5m was developed and could successfully be applied.