High lift configuration of a slotted natural laminar flow airfoil

Twiss, Daniel C.

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https://hdl.handle.net/2142/104908 Copy

Description

Title

High lift configuration of a slotted natural laminar flow airfoil

Author(s)

Twiss, Daniel C.

Issue Date

2019-04-24

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

Ansell, Phillip J.

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)

• High Lift
• Aerodynamics
• MSES
• Laminar Flow
• Multi-Element Airfoil

Abstract

Experiments were performed on a slotted natural laminar flow airfoil, the S414. The slotted natural laminar flow airfoil concept was developed to satisfy design constraints of high maximum lift and low profile drag. A two-element natural laminar flow configuration allows the typical rapid trailing-edge pressure recovery associated with NLF airfoils to be greatly reduced on the fore element, allowing for laminar flow across the entire airfoil upper surface. The slot provides a favorable injection of momentum to the flow over the aft-element upper surface, improving lift generation. However, an unfortunate side effect of the S414 is an abrupt, leading-edge stall type. This investigation focused on the development of a high-lift configuration of the S414 by altering the position of the aft element in order to characterize the feasibility of utilizing the aft element as a high-lift device. Computational analysis was performed on the S414 to determine suitable aft-element positions for high lift. Two basic repositioning approaches were used; one that deflected the aft element to increase the airfoil camber while maintaining the slot width of the original airfoil, and one that targeted the utilization of the fore-element dumping velocity. In addition, a plain flap was incorporated into the aft element. Performance predictions for the new aft-element configurations were generated using the computational flow solver MSES, and four alternative aft-element riggings were selected for experimental testing. Tests were performed in the University of Illinois 2.8 ft × 4 ft wind tunnel at Re = 1.8 × 10^6, M = 0.18. Using knowledge gained from the experimental tests, a fifth, empirically-derived configuration was developed. Both computational and experimental results indicated that effective utilization of the fore-element dumping velocity results in the largest increase in Cl. Orienting the aft element such that the flow off the fore element was discharged into a region of low pressure over the aft-element upper surface reduced the pressure recovery requirements at the fore-element trailing edge, allowing for enhanced lift production. In addition, a momentum injection was provided to the flow over the aft-element upper surface, promoting increased lift generation by the aft element as well. These techniques coupled with the deflection of the aft-element plain flap resulted in a 34% increase in Cl,max.

Graduation Semester

2019-05

Type of Resource

text

Permalink

http://hdl.handle.net/2142/104908

Copyright and License Information

Copyright 2019 by Daniel Twiss

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