Unsteady Aerodynamics - Unsteady Compressibility Effects for Modern Rotorcraft
Abstract
With the growing interest in faster helicopters, commercial unmanned vertical liftvehicles, and vertical-axis-wind-turbines, it becomes critical to understand the unsteady loading on the rotor blade so that more efficient designs can be produced. Theclassic unsteady airfoil theories are tools useful to predict loads on two-dimensionalrotor blade sections for moderate surging, pitching, and plunging motions. Specifically, Isaacs surging airfoil theory assumes a two-dimensional thin flat plate at smallangles of attack under a sinusoidally-oscillating freestream in an incompressible inviscid flow. The unsteady lift coefficient is then solved by the potential flow theory withthe Kutta condition at the trailing-edge. However, Isaacs surging airfoil theory hasnot been fully validated experimentally. As a result, this work is intended to investigate this surging airfoil theory experimentally and evaluate the key parameters insuch unsteady motion, the flow physics, and the validity of the various assumptions.Firstly, the wind tunnel at the Aerospace Research Center, the Ohio State University, is modified to generate a sinusoidally-oscillating freestream in the test sectionwith the design of rotating elliptical choke-vanes downstream. The modified unsteadywind tunnel is characterized to understand its unsteady response for a surging airfoil experiment, with the help of various intrusive measurements and analytical andnumerical tools.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 11, 2022
- Accession Number
- AD1196039
Entities
People
- James W Gregory
- Jeffrey P. Bons
- Wenbo P. Zhu
Organizations
- Ohio State University