CFD Analysis of a micro rotor in ground effect

Abstract

In this work, computational fluid dynamics is used to compare experimental results for a two-bladed small rotor Out of Ground Effect and In Ground Effect conditions. The paper focuses on the evalutation and prediction of the performance of the rotor and investigates the outwash generated in ground effect. Time and phase averaged outflow velocities with two different scaling methods are compared with experiments. The results are also scaled to a full-size rotor, and compared with the PAXman model of crew operating in close rotor proximity. A particle pickup model is also used showing the dust cloud generated by the rotor. Nomenclature Acronyms CF D Computational Fluid Dynamics DV E Degraded Visual Environment IGE In Ground Effect M T OW Maximum TakeOff Weight M U SCL Monotone Upstream Centred Schemes for Conservation Laws OGE Out of Ground Effect P IV Particle Image Velocimetry Greek ν Kinematic viscosity, m 2 /s Ω Rotor angular velocity, rad/s Ψ Local azimuth angle, deg ρ Density, kg/m 3 τ w Wall shear stress, kg/ms 2 θ Collective pitch at three-quarter radius, deg Latin a Speed of sound, m/s c Blade chord, m C Q Rotor torque coefficient, C Q = Q

Numerical Study of the Main Rotor Wake Structures and Induced Velocity Fields at the Tail Rotor Location When Flying Near the Ground

“…Figure 3 represents the performance diagram с Т =f(с Q ) for hover without ground effect. The calculation results coincide well with the available experimental data [24].…”

“…The work by Şahbaz et al (2019) [23] considers an isolated rotor in hover near an inclined ground surface. In the work by Rovere et al (2019) [24], based on HMB3-solver, the performance of small-size and large-size rotors in hover in ground effect has been studied. This research has been also focused on the study of the flow around the rotors.…”

Brownout Simulations of Model-Rotors In Ground Effect

“…Previous works show the full validation of the current methods [24]. Here a brief summary of the work is presented.…”

“…This is in agreement with what is shown in figure 5 (a), where the lightest produces weaker forces in comparison to the medium and the heavy. In [24] the computed shear stress on the ground of the domain allowed to calculate the particle velocity uplift threshold. It was shown that the peak of the uplift ratio ut/u*t is in proximity of 1 R distance from the rotor.…”

Safety analysis of Rotors In Ground Effect

“…Previous works showed the full validation of the same test case in OGE [32]. The IGE the rotor was modelled using two overset grids, and the ground was modelled imposing no-slip conditions.…”