SBIR-STTR Award

A novel damping model to damp acosutic pressures in gas turbine afterburners is proposed for development and validation in this SBIR project. The proposed model will account for as many of the physical phenomena present in the afterburenr as possible which will include grazing, bias, and mean flows, and heat release fluctuations that excite certain pressure modes and potentially cause screech.

Keywords:
Damping, Perforated Liner, Afterburner, Screech Attenuation, Fluctuating Heat Release, Grazing And Bias Flows

A Three-Dimensional Damping (TDD) Model and an Alpha V1.1 computer code successfully developed and demonstrated in Phase-I will be further developed to include additional important processes such as unsteady heat release and sheared flows. In addition, aero-acoustics and screech tests will be conducted to obtain a set data for model validation and evaluation.  

Benefit:
The proposed Three-Dimensional Damping (TDD) Model and the computer code will greatly benefit turbine engines OEM to better design screech liners and predict the acoustic modes that will be excited by the unsteady heat release. Such a model currently does not exist and will potentially replace the current lumped parameter-based screech liners design practices. The developed code will be transitioned to a turbine engine OEM that will utilize to improve their screech liners design to damp out both high and low order excited modes.  

Keywords:
Damping, Perforated Liner, Afterburner, Screech Attenuation, Fluctuating Heat Release, Grazing And Bias Flows ---------- A novel Integrated Predictive and Analysis Computational Technology (IPACT) for the critically needed solution of the sever high and low frequency screech instability problems in military Air Force (AF) flight propulsion systems such as afterburners will be further developed, validated , demonstrated, and incorporated into AF design and testing tools. Since current military and industry "cut and try" empirical approaches involving changes to afterburners flame-holders, chamber shape, fuel injection, velocity profiles, and flame piloting have proven inadequate.In such afterburner applications, the pressure, mechanical vibration, and, heat loads resulting from combustion screech instability, superimposed on the normal loading, are usually destructive and must be avoided at any cost.