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# Accession Number:

## ADA151696

# Title:

## Investigation of Potential and Viscous Flow Effects Contributing to Dynamic Stall.

# Descriptive Note:

## Master's thesis,

# Corporate Author:

## AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

# Report Date:

## 1984-09-01

# Pagination or Media Count:

##
88.0

# Abstract:

## This thesis explores the problem of dynamic stall, i.e. the stall of an airfoil undergoing pitching motion. General equations of continuity and momentum are developed for a non-inertial and unsteady control volume. They are written in momentum-integral form and the boundary layer on the pitching airfoil is computed using a modified von Karman-Pohlhausen method. The boundary layer edge velocity, velocity gradient and time rate of change of velocities required for the step by step integration of the von Karman-Pohlhausen working equations are obtained from the inviscid solution. The inviscid velocity profile along the surface of the airfoil is obtained by conformal mapping from the velocity profile around a rotating circular cylinder. Complex potential flow theory is used to obtain the velocity around the cylinder. The Kutta condition is continuously maintained at the point mapping to the trailing edge of the airfoil for each time step. This way, the flow is considered steady at each time step, but varies from one time step to the next when the angle of attack is increased. Originator supplied keywords include Pitching airfoil Boundary layer Unsteady momentum-Integral method MRS Model Mass introduction and Induced camber.

# Distribution Statement:

## APPROVED FOR PUBLIC RELEASE

#