Harry L. Runyan

Bio: Harry L. Runyan is an academic researcher. The author has contributed to research in topics: Aerodynamic force & Aerodynamics. The author has an hindex of 1, co-authored 1 publications receiving 13 citations.

Unsteady lifting surface theory applied to a propeller and helicopter rotor

Abstract: This thesis is concerned with the development of a theory for determining the aerodynamic forces for unsteady, compressible subsonic flow on a propeller and helicopter rotor. The acceleration potential method was used in developing the basic equations and the method has been programmed for the propeller on a computer and some results are given. The integral equations was solved by the doublet-lattice method, which consists of placing "load" lines at certain locations on the chord and satisfying the down-vash condition at other selected positions. The examples presented include the spanvise and chordwise loading on a rotating propeller for incompressible flow, an example of compressible flow calculations and finally, a calculation illustrating the loss of aerodynamic damping of a propeller blade due to the passage of the blade over its own wake.

Aerodynamics of V/STOL flight

Abstract: Aerodynamics of V/STOL flight , Aerodynamics of V/STOL flight , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Compressible Helicoidal Surface Theory for Propeller Aerodynamics and Noise

Abstract: Acceleration potential techniques from three-dimensional thin wing theory have been generalized for propeller and prop-fan analysis. Helicoidal reference surfaces take the place of the planar surface in wing theories; otherwise the theories are equivalent. The acoustic branch of the theory, including nonlinear source terms, extends and unifies frequency domain noise theories dating back to Gutin. For aerodynamic applications, it is shown that prop-fans satisfy well-known criteria for use of linearized theory at transonic speeds by virtue of small aspect ratio and small thickness ratio. The results are in the form of integral equations for downwash as functions of thickness and steady or unsteady loading distributions. For the case of no rotation, the kernel functions reduce to well-known kernels of wing theory. The analysis, within the restrictions of linearization , treats rigorously any planform and any flight condition including the combination of subsonic roots and supersonic tips typical of prop-fans. The effects of thickness, camber, angle of attack, sweep, offset, blade interference, and tip relief are all treated without approximation.

Integration of Airfoil Stall and Compressibility Models into a Propeller Blade Element Model

Abstract: The blade element method is an indispensible engineering design tool. It executes rapidly on a personal computer and is capable of accurate propeller performance predictions. An extensive literature survey reveals that for conventional high-aspect ratio propeller blades lifting surface and computational fluid dynamics approaches add a large degree of complexity without providing significantly improved performance prediction capabilities as compared to the blade element/vortex theory. The accuracy of the blade element method is, however, highly dependent on the fidelity of the airfoil aerodynamic model. The primary focus of this paper is on presenting a nonlinear aerodynamic model of airfoils that can be used in combination with the blade element method for enhanced propeller performance prediction over a wide range of advance ratios. The proposed nonlinear airfoil model includes effects of angles of attack up to 90 degrees and compressibility corrections. Results of this method are validated against experimental measurements. Excellent agreement between experiment and prediction is shown for subsonic helical tip Mach numbers.

Non-Linear Aerodynamic Modeling of Airfoils for Accurate Blade Element Propeller Performance Predictions

Abstract: The blade element method is an indispensible engineering design tool. It executes rapidly on a personal computer and is capable of accurate propeller performance predictions. An extensive literature survey serves to show that for conventional high-aspect ratio propeller blades lifting surface and computational fluid dynamics approaches add a large degree of complexity without providing significantly improved performance prediction capabilities as compared to the blade element/vortex theory. The accuracy of the blade element method is, however, highly dependent on the accuracy of the airfoil aerodynamic model. The primary focus of this paper is thus to present a non-linear aerodynamic model of airfoils to be used in combination with a blade element code for the purpose of propeller performance prediction. This non-linear airfoil model includes the behavior of the lift and drag coefficients up to 90 degrees angle of attack as well as corrections for compressible flow phenomena. Propeller performance predictions using the proposed airfoil model are compared against experimental data. Very good agreement between experiment and prediction validates the model, though it is limited to subsonic helical tip Mach numbers. The non-linear aerodynamic model presented in this paper adds to the versatility, efficiency, and accuracy of the blade element method.

Induced Drag Based on Leading Edge Suction for a Helicopter in Forward Flight

Abstract: Estimating induced drag for a helicopter in forward flight is a three-dimensional, unsteady aerodynamic problem complicated by fluid compressibility and wake geometry. Based on an acceleration potential approach, the chordwise velocity and the derivative d$/dt of the velocity potential at the leading edge of a thin rotor blade in subsonic flow were re-examined in this paper to assess unsteady and compressibility effects on the induced drag using a leading-edge suction model. The chordwise velocity was shown to have a singular and a continuous component. The d$/dt was shown to be continuous and hence does not contribute to induced drag. The induced drag calculated from the leading-edge suction model and the more traditional model to be referred to as the induced angle model were compared to quantify the differences in the two approaches. The results show that variations can be significant. While these variations cannot substantiate the validity of either approach, it is clear that the leading edge suction model is simpler to apply with fewer assumptions. b A A d