A Time-Marching Aeroelastic Method Applied to Propeller Flutter

Abstract

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, due to the highly detached nature of the flow, 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. This paper focuses on the validation of the aeroelastic method using the Commander propeller blade.

Estimation of three-dimensional aerodynamic damping using CFD

“…This is due to the fact that greater amounts of flow features, such as shedding open stall bubbles, are produced, and therefore cause greater variation in loads and blade deflections. This correlates to the dynamic stall investigations in which the aerodynamic damping is reduced for the quasi-3D SAS solutions, and to the model validation (15) in which the full 3D aeroelastic simulation using SAS was found to flutter, with the URANS producing a stable result.…”

“…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) .…”

“…Sea-level conditions were assumed, with the reference velocity and length, for the Reynolds number, selected as the tip Mach number at 1400(rpm) and tip chord length, respectively. Following the convergence of the rigid flow-field at 1400(rpm), the aeroelastic method was then used (15) .…”

“…As observed from Table 7, the URANS result produces a negative work estimation with the SAS solution producing positive work. From experimental (5) and simulation data (15) , it is known that this propeller blade is found to suffer from stall flutter. Analysis of the modal amplitudes from the simulation data found the SAS results to significantly increase in torsional content with the trend in terms of torsional stress observed across the blade.…”

Numerical Investigation of a Two-Bladed Propeller Inflow at Yaw

“…For the SAS formulation, an additional source term is added to the k − ω Shear Stress Transport (SST) equations which allows for the local adjustment of the von-Karman length scale and balances the contributions from resolved and statistical components. The SAS formulation in HMB3 has been used in the past for transonic cavity flows [31], missile projection [32] and stall flutter predictions [33]. This investigation was conducted to ensure that the standard URANS formulation closed with the k − ω turbulence model is accurate enough to capture the correct physics.…”