Title: Generalizing the Continuous Adjoint Method to Multifidelity Flowpaths and Multifunctionals, Applied to Hypersonic Inlets
Speaker: Heather Kline, PhD candidate, Stanford
Date: Friday, January 27, 2017
Time: 10:00 – 11:00 am
Location: NIA Room 141
Abstract: Hypersonic air-breathing propulsion systems offer greater efficiency through use of atmospheric oxygen rather than on-board compressed oxidizer tanks, for applications including access to space and hypersonic cruise, but require significant further development. The high cost of wind tunnel and flight testing motivates the increased use of computer simulations, and motivates advancements to simulation techniques. A number of the challenges remaining in aerospace craft design and simulation-based design techniques can be addressed by improving on methods of gradient computation, including gradient-based design and uncertainty quantification. This work focuses on developments towards generalizing a particular method of evaluating sensitivities and gradients (the continuous adjoin method) to a wider range of functions and multi-fidelity models.
The primary contributions of this work are:
- A new generalized adjoin functional that facilitates exible outflow-based functionals and functionals that depend on external models, which facilitates multi-fidelity flowpath design.
- A multi-objective adjoint implementation that utilizes the principle of superposition to combine already-implemented functionals.
- Optimization studies utilizing these methods on a hypersonic inlet modeled using a multi-fidelity flowpath, including a three-dimensional viscous inlet, showing relatively large performance changes for small changes to geometry.
Bio: Heather is an aerospace engineer and an open-source code developer, who has been very lucky to have spent the last several years criss-crossing the country in pursuit of knowledge, both at various NASA centers and in a University setting first at Rensselaer Polytechnic Institute and now at Stanford. Her first experience with NASA, and with LaRC, was as an undergraduate working at the Transonic Cryogenic Tunnel. More recently she returned to LaRC under a NASA Space Technology Research Fellowship working with the Hypersonic Airbreathing Propulsion Branch. She is now finishing her PhD in the Aerospace Design Laboratory at Stanford with Professor Juan Alonso, and is a developer on the open-source Computational Fluid Dynamics code SU2.