Theoretical and Practical Aspects of the Application of Resonant Combustion Chambers in Gas Turbines

Abstract

This paper discusses theoretical and experimental work carried out to determine the feasibility of a pressure-gain combustion system for gas turbines. Fundamental principles involved in the design of resonant combustors are considered and potential improvements in gas turbine performance are calculated by means of a piston-cylinder analogy. The results indicate that significant improvements in overall thermal efficiency and specific power output can be expected at relatively low pressure ratios but that these improvements become less effective at higher pressure ratios due to the influence of increased compressor delivery temperatures. The results of experimental work on a multiple combustor configuration show that the theoretical performance appears to be attainable and that, subject to further development work, resonant combustion chambers could be utilized to improve gas turbine performance.

The Rayleigh Efficiency of Pressure Gain Combustors

“…Rayleigh efficiencies achieved by other researchers[8,[11][12][13][14] and the Rayleigh efficiency predicted in this work.…”

“…The combustor's peak Rayleigh efficiency of 3.8% can be compared with the Rayleigh efficiencies of other published pulse combustors. Five measurements of pressure gain have been reported in the literature [8,[11][12][13][14]. For all five of these cases the combustor inlet and exit flows are steady, and the combustor temperature ratios are quoted.…”

The Rayleigh Efficiency of Pressure Gain Combustors

“…Fig. 10 Estimated Rayleigh efficiencies achieved by other researchers [8,[11][12][13][14] and the Rayleigh efficiency predicted in this work. Equation (21) shows that the effect on its thermal efficiency of introducing a pressure gain combustor into a gas turbine cycle can simply be determined by scaling the combustor's Rayleigh efficiency by a reheat factor, based on the two dead-state pressures, and adding it to the thermal efficiency of the baseline gas turbine.…”

“…Five measurements of pressure gain have been reported in the literature [8,[11][12][13][14]. For all five of these cases the combustor inlet and exit flows are steady, and the combustor temperature ratios are quoted.…”

Achieving Improved Cycle Efficiency via Pressure Gain Combustors

“…When applied to gas turbine cycles, it can be shown that under ideal conditions having a 10:1 pressure ratio and a 1200 K turbine inlet temperature, the efficiencies of a constant volume versus a constant pressure combustion system, are 54 percent and 48 percent, respectively, Gemmen, et al (1994). Past investigations have attempted to apply this technology to gas turbines with varying degrees of success; Thring (1961), Muller (1971), Kentfield andO'Blenes (1987a, 1987b), to name a few. While these investigations have indicated that it is possible to achieve pressure gain, no investigation has addressed the combined issues of pressure gain, pollutant reduction, and engine reliability.…”