Dr. Zinn’s research focuses on understanding the dynamics of flow, combustion and propulsion systems, and their active control. This is a multidisciplinary research activity that requires an understanding of fluid mechanics, thermodynamics, combustion, acoustics, and propulsion. Dr. Zinn’s current research program is supported by the Air Force, Navy, Army, the Department of Energy and industry, and includes investigations whose objectives are to improve the performance of helicopters’ gas turbines, rocket motors, low-emission gas turbines, and onboard ship incinerators. Each of these programs investigates the use of a specific control system to improve the performance of the process or system. For example, the Air Force and Department of Energy programs investigate the application of an active control system to eliminate detrimental combustion instabilities, which manifest themselves as large amplitude combustor pressure oscillations that often result in system and/or mission failure.
Dr. Zinn’s studies investigate the causes of these pressure oscillations and control systems that could prevent their occurrence. These studies have recently demonstrated that combustion instabilities can be damped in practically real time (that is, within 40 milliseconds!) by modulating the flow rate of a fraction of the fuel input into the combustor. Interestingly, the fuel injector that was developed to modulate the fuel flow rate into the combustor is now being considered for automotive applications; for example, the reduction of soot emissions from diesel engines by multiple injections of the fuel into the combustor. In the Navy program, Dr. Zinn’s group is using sound waves, generated by a pulse combustion process, to improve the mixing and heat transfer within the incinerator and, thus, accelerate the incineration process and reduce the required incinerator volume.