A wind-tunnel based study of helicopter tail rotor blade vortex interaction

Abstract

The interaction of a helicopter tail rotor blade with the tip vortex system from the main rotor is a significant source of noise and, in some flight states, can produce marked reductions in control effectiveness. This paper describes a series of wind-tunnel tests to simulate tail rotor blade vortex interaction with a view to providing data for the development and validation of numerical simulations of the phenomenon. In the experiments, which were carried out in the Argyll wind-tunnel of Glasgow University, a single-bladed rotor located in the tunnel’s contraction was used to generate the tip vortex which travelled downstream into the working section where it interacted with a model tail rotor. The tail rotor was instrumented with miniature pressure transducers that measured the aerodynamic response during the interaction. The results suggest that the rotor blade vortex interaction is similar in form to that measured at much higher spatial resolution on a fixed, non-rotating blade. The combination of the two datasets, therefore, provides a valuable resource for the development and validation of predictive schemes.

Helicopter tail rotor orthogonal blade vortex interaction

“…Shed Vorticity Trailed Vorticity Experiment Figure 22 Comparison of computed wake geometry with hot-wire measurements of the wake produced by the single-bladed vortex generator in the Glasgow University 1.15m x 0.85m low speed wind tunnel [60]. r/R=0.69 Figure 38 Pressure coefficient variations measured near the upper surface leading edge of a model tail rotor (x/c=0.06, r/R=0.69) in the Glasgow University 2.65m x 2.04m low speed wind tunnel [64]. The box highlights an OBVI event.…”

“…r/R=0.69 Figure 39 Pressure coefficient variations measured near the lower surface leading edge of a model tail rotor (x/c=0.1, r/R=0.69) in the Glasgow University 2.65m x 2.04m low speed wind tunnel [64]. The box highlights an OBVI event.…”

“…x/c=0.75 Figure 40 Pressure coefficient variations at two upper surface locations on a tail rotor blade undergoing blade vortex interaction measured in the Glasgow University 2.65m x 2.04m low speed wind tunnel [64]. Figure 50.…”

“…In the second series of tests, a model tail rotor was placed in the path of the convecting vortex in order to study the vortex interaction with a rotating blade [64]. The tail rotor system, which had been designed at the University of Southampton, was supplied by Westland Helicopters Limited, but the blades were re-designed and constructed by the University of Glasgow in order to accommodate appropriate pressure transducers.…”

Influence of the wake model on the thrust of oscillating foil

“…the timing of vortices' shedding predicted by the model). It is important to point out that such pressure measurements are technically feasible as there are well-established measurement techniques in experimental fluid dynamics research that could be potentially utilized [25,26]. Moreover, in a previous study [10] the number of time steps for each cycle was chosen on the basis of existing experimental data regarding the thrust coefficient as a function of the Strouhal number [22], i.e.…”