Vortices are the sinews and muscles of fluid motions.

–Dietrich Küchemann, Aerodynamicist (1965)

Dr. Jonathan C. French received his B.S. in Mechanical Engineering (with High Honors) from Worcester Polytechnic Institute in May 1991.  He then joined the University of Tennessee Space Institute where he earned a Master of Science degree in Mechanical Engineering in December, 1993. He also received a Ph.D. in Engineering Science and Mechanics in December, 1996.  His graduate work focused on computational aero-acoustics, which has helped him extend geometrically simplified analytic stability equations into numerical tools applicable to complex geometries. Through his research, he established the viability of a new dispersionless numerical method for the Helmholtz equation under a NASA Lewis (Glenn) grant. After presenting this numerical method to an international forum in Munich, Germany, he extended the approach to acoustics problems involving inhomogeneous media. He also modeled the exit flow from a jet turbofan for use in acoustic analyses under a NASA Lewis (Glenn) research contract. Along similar lines, he designed a graphical interface and coordinated the implementation of three computational codes for a jet inlet acoustics design program under a GM Allison contract.

After a brief stint as an Acoustics Consultant to AeroAstro (computing 3D acoustic modes of a liquid rocket engine), he joined Lockheed Martin Tactical Aircraft Systems where he performed warfare Monte-Carlo simulations of ground control responses to incoming aircraft attack.  He then joined Software and Engineering Associates (SEA*), Carson City, Nevada, in March 1998.

At SEA, he improved and developed new modules for solid rocket propulsion analysis software. He extended the capabilities of the Solid Performance Program (SPP) to include improved perimeter computation, generation of 3D FEM surface meshes of the propellant grain during burnback, automated grid generation, and an axially burning embedded wire model.  Under a Navy SBIR for solid rocket motor combustion stability, he developed a 3D acoustic eigensolver code linked to the SPP code for combustion stability analysis. Through a second Navy SBIR for non-linear SRM combustion stability modeling, he improved the linkage between SPP and the Standard Stability Prediction program (SSP), and implemented non-linear analysis procedures for prediction of limiting pressure amplitudes. He managed four research subcontractors, convened two workshops on non-linear combustion stability modeling, and presented linear and non-linear combustion stability results at several AIAA Joint Propulsion and JANNAF conferences, and at a Defense Exchange Agreement meeting at ONERA in France (most papers available online at http://www.seainc.com/papers).

He has recently  modeled the grain design, ballistics and stability of tactical SRMs under industrial and military contracts. Under contract from Thiokol, he improved the SPP / SSP linkage to correct the RSRM stability analysis. As part of the Shuttle Columbia investigation for MSFC, he evaluated the burnback of a portion of the Shuttle’s booster separation motor.

In addition to his research and development intensive efforts, he has been active in teaching and organizing workshops on combustion instability.  He has guest-lectured on rocket combustion stability codes and nonlinear combustion stability at the University of Tennessee Space Institute. He has also taught a course on the implementation of a nacelle acoustic radiation code at Rolls Royce Allison, at the same time correcting the code to incorporate the effect of impedance from acoustic liners.

Dr. French is presently the Principle Engineer heading SEA’s combustion stability efforts. His research and job interests remain centered around the development of the Standard Stability Prediction program (SSP) used by the U.S. Navy, the U.S. Air force and many other entities involved in aerospace research. He has published more than twenty journals and conference papers in the areas of advanced combustion technology for solid rocket motors and jet engines. He has been working with combustion instability and development of the code for improving prediction of instability.  Under an NSF STTR grant written by Drs. Majdalani and French, work is underway in incorporating the effects of hydrodynamic instability.

*SEA’s mission is to develop and maintain design codes for the aerospace industry. Their codes are intended for use in the design cycle, and as such must return reasonable results quickly. SEA maintains the JANNAF standard design codes for solid and liquid propulsion systems. Through research contracts and industry support, SEA adds new features to permit their codes to address new problems. SEA maintains a sustainable business by adding new features to existing design codes and then providing upgrades to the entire U.S. rocket community.