Jonathan F.

Combustion Stability Modeling Analysis Led a team of combustion stability experts in predicting the combustion stability of solid rocket motors, liquid rocket engines, scramjets and augmentors for NASA, the Air Force, MDA and ATK. Constructed computational models of combustion chambers by taking specifications provided by the customer, reduced the design to the pertinent details depending on length scale, used authored Fortran codes for grid generation, implemented NASA CFD codes to obtain steady flow field, and performed subsequent acoustic analyses of the chamber using the CFD results to impart the influence of the steady flow to the acoustics. Utilized existing CFD results when available, but most analyses were of legacy systems, requiring extraction of geometry from printed figures or blueprints. Post processed CFD and acoustics results to predict engine stability. Correlated observations from experimental tuning of resonator cavities on the Aero-Astro PA-E liquid rocket engine to corresponding changes in the chamber’s mode shapes. Computational Tool Development Encoded a suite of Plot3D grid generation codes to facilitate modeling a wide variety of combustion devices. Developed a quadratic eigenvalue acoustics program that calculates complex valued acoustic modes of cavities (axisymmetric and 3D) with the influence of a steady flow field, including a sonic nozzle. It uses multiple blocks of structured grids in order to model complicated geometries. Modified the industry standard ARPACK / P-ARPACK Fortran code to filter by ranges of real and complex parts of eigenvalues, and allow for restart. Wrote manual for the acoustics code and packaged it for sale. Invented a new approach to calculating the nozzle damping for a sonic nozzle, which was subsequently published in the Journal of Propulsion and Power.