High-Fidelity Computational Fluid Dynamics Methods for the Simulation of Propeller Stall Flutter

Abstract

Brown, N. (2019) Highfidelity computational fluid dynamics methods for the simulation of propeller stall flutter. A time-marching aeroelastic method developed for the study of propeller flutter is presented and validated. Propeller flutter can take many forms with stall, whirl and classical flutter being the primary responses. These types of flutter require accurate capture of the non-linear aerodynamics associated with propeller blades. Stall flutter in particular needs detailed unsteady flow modelling. With the development of modern propeller designs potentially adjusting the flutter boundary and the development of faster computing power, CFD is required to ensure accurate capture of aerodynamics. Given the lack of reliable experimental stall flutter data for propellers, the method was focused on observing the correct qualitative behaviour with a comparison made between URANS and Scale-Adaptive Simulation (SAS). Greek α s m = Model amplitude of mode m of solid s (m/kg) ζ m = Damping coefficient (-) ρ = Fluid density (kg/m 3 ) ψ s m = Normalised m th mode displacement of solid s (m/kg) ψ s = Normalised displacement of solid s (m/kg) ω m = Natural frequency of mode m Ω CV = Control volume size Subscripts i, j, k = Mesh cell indices

A computational fluid dynamic acoustic investigation of a tiltwing eVTOL concept aircraft

“…Good agreement in terms of aerodynamics, acoustics and aeroelasticity were seen by all [27,28,29,30].…”

An Aeroacoustic Investigation of a Tiltwing eVTOL Concept Aircraft

“…Previous investigations using HMB3 have provided propeller flow validation in both installed and isolated conditions, by comparison with the experimental results of the Joint Open Rotor Propeller (JORP) blade [9], the Improving the Propulsion Aerodynamic and aCoustics of Turboprop Aircraft (IMPACTA) wind tunnel tests [10,11] and the model aircraft propeller inflow investigation at the University of Glasgow. Good agreement in terms of aerodynamics, acoustics and aeroelasticity were seen by all [12][13][14][15]. In addition to propeller flows, HMB3 has also been validated for tiltrotors, including the AW609 and XV-15 [16], for hover and forward flight.…”

Estimation of three-dimensional aerodynamic damping using CFD

“…The core functionality of HMB3 is CFD, however its use has been extended in recent years to include whole engineering applications, including helicopter rotor aeroelasticity (12) and propeller validation (13,14) . In addition to this, the time-marching aeroelastic method of HMB3 has been validated with respect to propeller stall flutter for the Commander propeller blade (15,16) .…”

“…The aeroelastic framework of HMB3 is based on the modal method (16,24) . This method uses externally computed structural modes and a mesh deformation module based on the inverse distance weighting interpolation.…”

“…Figure 10. Time history of the modal amplitude results and torsional stress trends across the blade for the aeroelastic validation (16) .…”