High Frequency Laser Energy Deposition for Hypersonic Active Flow Control on a Flared Cone

Active flow control (AFC) in the hypersonic regime offers a promising method for rapid manipulation of the aerodynamic flow field without relying on traditional control surfaces, which can have actuation and flow field responses that are too slow for this high-speed regime. A practical AFC approach involves high-frequency laser energy deposition through the ablation of a metallic surface into the flow. The resulting laser-induced plume generates sustained transient changes downstream of the targeted flow field, effectively altering local high-speed flow parameters. This thesis applies the previously described energy deposition AFC technique to a modified NASA 91-6 flared cone to investigate downstream influence on the well-documented transitory behavior of the cone. Experiments were conducted in the Actively Controlled Expansion (ACE) hypersonic wind tunnel at the National Aerothermochemistry and Hypersonic Flight Laboratory (NAHL). The ACE tunnel variable nozzle enabled the collection of two test conditions per run. For each experiment, a pulse-burst laser (PBL) system, housed within the Aerospace Laboratory for Lasers, Electromagnetics, and Optics (ALLEMO), varied the laser's repetition rate and energy output. The PBL system enabled testing of three laser repetition rates, each of which varied the output energies. Testing conditions included four different Mach numbers at a targeted unit Reynolds number of 3 x 106. The campaign successfully captured flow-field and shock-wave manipulation, as well as amplification of the second mode instability and other transitory indicators within the hypersonic boundary layer. Laser-induced harmonics were observed at higher Mach numbers, consistent with the linear stability theory supporting Mack mode instabilities. Focused laser differential interferometry observed effects of the ablative plume absorbing energy when varying the laser system's output, while the pressure transducers captured ablation-induced transitory behaviors across the parameters of interest.

Name thesis:degree_name

Master of Science

Discipline thesis:degree_discipline

Aerospace Engineering

Grantor

Texas A&M University

Year dc:date.issued

2025

Author dc:creator

• Vijayakumar, Jenith 2001-

Advisor dc:contributor.advisor

• Tichenor, Nathan

Committee members dc:contributor.committeemember

• Siddiqui, Farhan
• Staack, David

• Engineering, Aerospace

Language dc:language.iso

English

Handle dc:identifier.uri

https://hdl.handle.net/1969.1/1600962

OAI record oai:identifier

https://oaktrust.library.tamu.edu/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Aoaktrust.library.tamu.edu%3A1969.1%2F1600962