Development of an Unsteady Aerodynamic Analysis Module for Rotor Comprehensive Analysis Code

Abstract

The inherent aeromechanical complexity of a rotor system necessitated the comprehensive analysis code for helicopter rotor system. In the present study, an aerodynamic analysis module has been developed as a part of rotorcraft comprehensive program. Aerodynamic analysis module is largely classified into airload calculation routine and inflow analysis routine. For airload calculation, quasi-steady analysis model is employed based on the blade element method with the correction of unsteady aerodynamic effects. In order to take unsteady effects -body motion effects and dynamic stall -into account, aerodynamic coefficients are corrected by considering Leishman-Beddoes's unsteady model. Various inflow models and vortex wake models are implemented in the aerodynamic module to consider wake induced inflow. Specifically, linear inflow, dynamic inflow, prescribed wake and free wake model are integrated into the present module. The aerodynamic characteristics of each method are compared and validated against available experimental data such as Elliot's induced inflow distribution and sectional normal force coefficients of AH-1G. In order to validate unsteady aerodynamic model, 2-D unsteady model for NACA0012 airfoil is validated against aerodynamic coefficients of McAlister's experimental data.

Aeroelastic Analysis of a Hingeless Rotor Using a Dynamic Wake Model

“…Validity of the Drees model in an aeroelastic analysis has been shown by Jeon and Lee [13]. The Peters-He dynamic wake model has been verified, through comparison with the Elliot model, by Lee et al [11]. The aerodynamic coefficients (c l , c d , and c m ) necessary for calculation of the inflow are obtained from a table of NACA0012 airfoil data.…”

“…Because the pressure distribution over the rotor disk is determined as a function of the airload acting on each blade, it will be possible to take the number of blades into account. Detailed descriptions of the dynamic wake model are found in [7,11].…”

“…It is one of the simple approaches available for aeroelastic analysis, because the computation is accomplished quickly [10]. The aerodynamic coefficients are interpolated from the 2-D airfoil data table [11].…”

Helicopter Aeroelastic Analysis in Forward Flight Using Dynamic Wake Model

“…Time integration of the linearized perturbation equations of motion is conducted by using the fourth-order Runge-Kutta method. analysis has been shown by Jeon 13 Peters and He dynamic wake model has been verified, through comparison with Elliot's test results, by Lee et al 11 . The aerodynamic coefficients (c l , c d , and c m ) necessary for calculation of the inflow are obtained from a table of NACA0012 airfoil data.…”

“…It is one of the simple approaches available for aeroelastic analysis because the computation is accoplished quickly 10 . The aerodynamic coefficients are interpolated from the 2-D airfoil data table 11 .…”