ABSTRACT Within the DLR project AcTOR (Active Twist Optimized Rotor), a four-bladed, fully instrumented active twist model rotor was built. This active twist rotor was supposed to be tested in the LLF (Low Speed Facility) of DNW within... more
ABSTRACT Within the DLR project AcTOR (Active Twist Optimized Rotor), a four-bladed, fully instrumented active twist model rotor was built. This active twist rotor was supposed to be tested in the LLF (Low Speed Facility) of DNW within the framework of the international STAR (Smart-Twisting Active Rotor) consortium. The STAR consortium is composed of ONERA, NASA, US~Army AFDD, JAXA, Konkuk University, KARI, and DNW. In preparation to the planned DNW wind tunnel tests, a comprehensive preparatory test was conducted at the rotor preparation hall of DLR. The aim of this test had been the proof of functionality for the complete wind tunnel model with emphasis on active twist and blade performance. Besides basic rotor data, also advanced data concerning blade deformation and vortex properties for hover applications with and without active twist were aquired. Although, the functionality of the active twist blades and the rotor test stand could be demonstrated successfully, endurance problems occured during the test and hindered the project from a wind tunnel entry. Nevertheless, a comprehensive data base on an active twist model rotor in hover has been gained. The paper provides an overview of the preparatory test and presents representative results.
In a major cooperative program within the existing US-German and US-French Memoranda of Understanding/Agreements (MOU/MOA), researchers from German DLR, French ONERA, NASA Langley, and the US Army Aeroflightdynamics Directorate (AFDD)... more
In a major cooperative program within the existing US-German and US-French Memoranda of Understanding/Agreements (MOU/MOA), researchers from German DLR, French ONERA, NASA Langley, and the US Army Aeroflightdynamics Directorate (AFDD) conducted a comprehensive experimental program in October 2001 with a 40% -geometrically and aeroelastically scaled model of a BO-105 main rotor in the open-jet anechoic test section of the German-Dutch
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Abstract: In a major cooperative program within the existing US-German and US-French Memoranda of Understanding/Agreements (MOU/MOA), researchers from German DLR, French ONERA, NASA Langley, and the US Army Aeroflightdynamics Directorate... more
Abstract: In a major cooperative program within the existing US-German and US-French Memoranda of Understanding/Agreements (MOU/MOA), researchers from German DLR, French ONERA, NASA Langley, and the US Army Aeroflightdynamics Directorate (AFDD) ...
Research Interests:
Research Interests:
The flow field around a helicopter is characterised by its inherent complexity including effects of fluid–structure interference, shock–boundary layer interaction and dynamic stall. Since the advancement of computational fluid dynamics... more
The flow field around a helicopter is characterised by its inherent complexity including effects of fluid–structure interference, shock–boundary layer interaction and dynamic stall. Since the advancement of computational fluid dynamics and computing capabilities has led to an increasing demand for experimental validation data, a comprehensive wind tunnel test campaign of a fully equipped and motorised generic medium transport helicopter was conducted in the framework of the GOAHEAD project. Different model configurations (with or without main/tail rotor blades) and several flight conditions were investigated. In this paper, the results of the three-component velocity field measurements around the model are surveyed. The effect of the interaction between the main rotor wake and the fuselage for cruise/tail shake flight conditions was analysed based on the flow characteristics downstream from the rotor hub and the rear fuselage hatch. The results indicated a sensible increment of the intensity of the vortex shedding from the lower part of the fuselage and a strong interaction between the blade vortex filaments and the wakes shed by the rotor hub and by the engine exhaust areas. The pitch-up phenomenon was addressed, detecting the blade tip vortices impacting on the horizontal tail plane. For high-speed forward flight, the shock wave formation on the advancing blade was detected, measuring the location on the blade chord and the intensity. Furthermore, dynamic stall on the retreating main rotor blade in high-speed forward flight was observed at r/R = 0.5 and 0.6. The analysis of the substructures forming the dynamic stall vortex revealed an unexpected spatial concentration suggesting a rotational stabilisation of large-scale structures on the blade.
Research Interests:
Research Interests:
ABSTRACT The flow field around a helicopter is characterised by its inherent complexity including effects of fluid-structure interference, shock-boundary layer interaction, and dynamic stall. Since the advancement of computational fluid... more
ABSTRACT The flow field around a helicopter is characterised by its inherent complexity including effects of fluid-structure interference, shock-boundary layer interaction, and dynamic stall. Since the advancement of computational fluid dynamics and computing capabilities has led to an increasing demand for experimental validation data, a comprehensive wind tunnel test of a fully equipped and motorized generic medium transport helicopter was conducted in the framework of the GOAHEAD project. In this paper the results of the three-component velocity field measurements are summarized. The effect of the interaction between the main rotor wake and the fuselage for cruise/tail shake conditions was investigated, detecting and analysing the flow characteristics downstream the rotor hub and the rear hatch. The results indicated a sensible increment of the intensity of the vortices shedding form the lower part of the fuselage and a strong influence of the main rotor in the upper region. Furthermore, the pitch up phenomenon was considered, detecting the blade tip vortices impacting on the horizontal tail plane. For high speed forward flight the shock wave forming on the advancing blade was investigated, measuring the location on the blade chord and the intensity. Furthermore, dynamic stall on the retreating main rotor blade in hight-speed forward flight was observed at 40% and 50% blade radius. The analysis of the substructures forming the dynamic stall vortex revealed an unexpected spatial concentration suggesting a rotational stabilization of large scale structures on the blade.