Date of Award

12-2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Aerospace, Physics, and Space Sciences

First Advisor

Hamidreza Najafi

Second Advisor

Hamid Hefazi

Third Advisor

Troy Nguyen

Abstract

Direct measurement of flight environment on a heat shield of a Reusable Launch Vehicle (RLV) is critical due to the extremely aerothermal heating experiences during the reentry phase. An alternative approach is to install thermocouple several millimeters below the heat shield surface to measure the heat shield temperature response and solve the associated inverse heat conduction problem (IHCP) in order to reconstruct the surface heat flux using the measured temperature response. The material properties and thicknesses of the Thermal protection system (TPS) make the reconstruction process more challenging when the thermocouples are placed far away from the surface. The focus of this thesis is to develop a solution for IHCP’s using digital filter approach. A step by step solution strategy is developed using Tikhonov regularization method to reconstruct the surface heat flux on the surface of a Four-layer TPS model. The solution to the inverse problem is written in a digital filter form which allows real-time surface heat flux estimation. To evaluate the solution, several numerical test cases were developed in ANSYS. The results show that the developed filter based solution can successfully estimate transient surface heat fluxes using temperature measurement data from the inner layer in a near real-time fashion. A parametric analysis is also conducted in order to investigate the effect of a variety of parameters (sensor location, the thickness of the layers and time step) on the performance of the solution.

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