2026-09-22T12:43:01Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/104908 2023-07-11 col_2142_5131 col_2142_14800 com_2142_5130 com_2142_14799 com_2142_234

Ansell, Phillip J. Twiss, Daniel C. 2019-08-23T20:01:14Z 2019-08-23T20:01:14Z 2019-04-24 2019-05 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. Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2019-08-22 without embargo terms The student, Daniel Twiss, accepted the attached license on 2019-04-23 at 12:53. The student, Daniel Twiss, submitted this Thesis for approval on 2019-04-23 at 13:19. This Thesis was approved for publication on 2019-04-24 at 14:57. DSpace SAF Submission Ingestion Package generated from Vireo submission #13842 on 2019-08-22 at 14:46:05 Made available in DSpace on 2019-08-23T20:01:14Z (GMT). No. of bitstreams: 2 TWISS-THESIS-2019.pdf: 9142967 bytes, checksum: 30880396e6a1403038f98bce632d7fb3 (MD5) LICENSE.txt: 4209 bytes, checksum: 65e4063b4b93eead5d87488ad6ea755b (MD5) Previous issue date: 2019-04-24 application/pdf http://hdl.handle.net/2142/104908 en Copyright 2019 by Daniel Twiss High Lift Aerodynamics MSES Laminar Flow Multi-Element Airfoil High lift configuration of a slotted natural laminar flow airfoil text text Aerospace Engineering Aerospace Engineering University of Illinois at Urbana-Champaign Thesis M.S.