| The focus of the research work reported in this dissertation was to determine new methods that may be applied to turbine or jet combustion processes to monitor performance acoustically; to show how passive acoustic methods can be used to measure engine performance; and finally, how acoustic methods may be used to generate isotherms in these types of engines.;Acoustic pyrometry is introduced and the difference between an active acoustic pyrometer and a passive system is explained. The passive system is of main focus because in most engines the combustion noise destroys the active transmitted signal.;A brief background of turbine engines and the way in which fuel is supplied to turbines is reported. The inadequacies that are inherent with post-combustion readings are discussed. Other concerns such as engine wear, emissions, and part failure are explored and reasons are given as to why a passive acoustic method may be the key to improving these areas of concern.;Applicable theories include: speed of sound, molecular weight and constituents of gases, cross correlation, frequency spectrum, and resonation.;The dissertation then reports on experimental procedures and results where the data collection and data analysis is thoroughly explained for both NASA and Rolls-Royce experiments respectively. Tables, graphs and equations highlight the applied theory and experimental results from the NASA Glen Research Center and the Rolls-Royce facilities in Indiana. An error analysis of the developed passive acoustic method is provided.;The new passive acoustic method developed in this work determines or estimates the dominant or other frequencies of sound (vibration or pressure fluctuation) emanating from the combustor or its associated structure and, from that determination, assesses the fuel/air ratio and temperature within the combustor (e.g. a turbine combustor).;The conclusion explains advantages of the new passive acoustic pyrometry such as real-time readings, more robust systems, fewer components, less expenses, more efficient maintenance and increased ability to monitor, regulate and control turbine engines.;A section on future direction and work provides a brief overview of new efforts in the field of monitoring engines and turbines as well as recommending continuing research and application of this new method. |
