Actuator Disk Model with Improved Tip Loss Correction for Hover and Forward Flight Rotor Analysis

Abstract

A novel actuator disk model (ADM) coupled with lifting-line theory is proposed in this paper. Several virtual planform blades are placed on a disk plane with a constant azimuthal interval, and the lifting-line theory is applied to each blade to predict the effective angle of attack. The proposed model considers the local lift and drag forces acting on disk surface cells by interpolating the predicted effective angle of attack with various azimuth angles to the actuator disk plane; therefore, the proposed model considers individual blade tip vortices without tip loss functions. Experimental data for hover and forward flight rotors are used to validate the proposed model. For hovering flight, sectional thrust based on collective pitch angles predicted by the modified ADM was similar to that obtained in the experiments. For forward flight, the inflow above the rotor estimated by the proposed ADM was similar to that obtained in the experiments and by using other numerical methods. Thus, the developed ADM can be used for rotor performance analysis under the main flight conditions of V/STOL.

Combination of Advanced Actuator Line/Disk Model and a High-Order Unstructured Finite Volume Solver for Helicopter Rotors

“…Although vortex-based correction has recently been devised [13], its demanding assumptions and intricate computing techniques make it unsuitable for extension to rotor computations. Son [14] developed a tip correction method for ADM. Additionally, A filtered ALM [15] was first used in fixed-wing applications and has been expanded to wind turbine simulations, using a finite difference methodology. It gives a effective way to use ALM on coarser grids, but this method employs a finite difference approach that leads to lift overestimations at the blade tip section.…”