Kurt Pengel

Key Results from a Higher Harmonic Control Aeroacoustic Rotor Test (HART)

In a major cooperative research program within existing US-German and US-French Memoranda of Understandings (MoUs) a comprehensive experimental study was conducted with a 40-percent geometrically and dynamically scaled BO-105 main rotor operated in the open-jet-anechoic test section of the German-Dutch Wind Tunnel (DNW). The objectives of the program were to improve the physical understanding and the mathematical modelling of the effects of the higher harmonic blade pitch control technique on blade-vortex interaction (BVI) impulsive noise and vibration reduction. A unique set of acoustic, dynamic, dynamic response, performance, and rotor wake data were acquired with a pressure and strain gauge instrumentedblade and by application of non-intrusive measurement techniques. This paper is focused on the experimental part of this research program, termed Higher-harmonic-control Aeroacoustic Rotor Test (HART) which was jointly performed by researchers from the.

Rotor Wake Vortex Definition-Evaluation of 3-C PIV Results of the HART-II Study:

An evaluation is made of extensive three-component (3-C) particle image velocimetry (PIV) measurements within the wake across a rotor disk plane. The model is a 40 percent scale BO-105 helicopter main rotor in forward flight simulation. This study is part of the HART II test program conducted in the German-Dutch Wind Tunnel (DNW). Included are wake vortex field measurements over the advancing and retreating sides of the rotor operating at a typical descent landing condition important for impulsive blade-vortex interaction (BVI) noise. Also included are advancing side results for rotor angle variations from climb to steep descent. Using detailed PIV vector maps of the vortex fields, methods of extracting key vortex parameters are examined and a new method was developed and evaluated. An objective processing method, involving a center-of-vorticity criterion and a vorticity “disk” integration, was used to determine vortex core size, strength, core velocity distribution characteristics, and unsteadiness. These parameters are mapped over the rotor disk and offer unique physical insight for these parameters of importance for rotor noise and vibration prediction.

From Aeroacoustics Basic Research to a Modern Low Noise Rotor Blade

In 2015, Airbus Helicopters unveiled the secrecy around its Dauphin successor and presented the all new H160 helicopter. A special feature that immediately attracted attention was its unusual and revolutionary fore-aft swept main rotor blade. This design, which aims to significantly reduce the blade-vortex interaction noise signature and reduce high-speed forward flight power requirements, was first investigated in the 1990s. At this time, DLR and ONERA formed a joint team to acoustically optimize a rectangular reference rotor blade. Based on state-of-the-art comprehensive rotor codes and a 50/50 work share, the ERATO rotor blade design was developed, patented worldwide and tested on both a rotor test rig and in the wind tunnel. Airbus Helicopters (then: Eurocopter) adopted the design, optimized hover and forward flight high lift performance and prepared it for serial production, as the Blue EdgeTM rotor blade on the Airbus Helicopters H160 helicopter.