Aerodynamics of lifting surfaces in propeller slipstreams

Chadha, Sparsh Adhir

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https://hdl.handle.net/2142/95413 Copy

Description

Title

Aerodynamics of lifting surfaces in propeller slipstreams

Author(s)

Chadha, Sparsh Adhir

Issue Date

2016-12-09

Director of Research (if dissertation) or Advisor (if thesis)

Selig, Michael S.

Department of Study

Aerospace Engineering

Discipline

Aerospace Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Aerodynamics
• Computational fluid dynamics (CFD)
• Airfoils
• Wings
• Propeller Slipstreams
• Distributed Propulsion
• Propeller wing interaction
• Slipstream effects

Abstract

The high-speed flow in the wake of the propeller also known as propeller wash, or simply propwash, can severely affect the aerodynamic forces on a lifting surface. Steady-state computational results for a symmetric SD8020 airfoil with chord length of 1 ft in a propeller slipstream at a freestream Reynolds number of 100,000 are presented in this study. ANSYS FLUENT was used to solve the flow equations inside the control volume. For the two-dimensional analysis, the propeller was modeled as an actuator line across which the nondimensionalized pressure jump was varied from 3.4 to 13.6. The aerodynamic performance was obtained for the airfoil in configurations with varying horizontal and vertical distance between the actuator line center and airfoil leading edge as well as different diameter-to-chord ratios. As compared with the clean configuration, the lift coefficient and drag coefficient increased by a factor of 5 and 25, respectively, for the slipstream with the highest pressure jump case. The two-dimensional lift curve remained linear throughout the angle of attack range from 0 to 12 deg, and aerodynamic stall was not observed for the computed cases. In general, reducing the diameter-to-chord ratio and shifting the airfoil downstream improved aerodynamic performance. Vertical offset in the airfoil location affected the local flow due to the slipstream and resulted in a low wing configuration producing high lift, and low drag relative to the baseline configuration. Three-dimensional simulations were performed with a circular actuator disk and a rectangular span lifting surface with a semi-span of 1 ft. Due to the wall mirroring effect, the setup simulated a system with infinite propellers upstream of a lifting surface with infinite span. A high spanwise variation of lift in the slipstream shear layer resulted in induced trailing vortices. The trailing vortices caused downwash on the sections within the slipstream flow and upwash on the sections located outside the slipstream which led to an early onset of stall on the outboard sections.

Graduation Semester

2016-12

Type of Resource

text

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http://hdl.handle.net/2142/95413

Copyright and License Information

Copyright 2016 by Sparsh Adhir Chadha

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