Pressure Gain Combustion for Gas Turbines: Analysis of a Fully Coupled Engine Model

The “Shockless Explosion Combustion" (SEC) concept for gas turbinecombustors, introduced in 2014, approximates constant volume combustion (CVC)by harnessing acoustic confinement of autoigniting gas packets. The resultingpressure waves simultaneously transmit combustion energy to a turbine plenumand facilitate the combustor's recharging against an average pressure gain.Challenges in actualizing an SEC-driven gas turbine include i) the creation ofcharge stratifications for nearly homogeneous autoignition, ii) protecting theturbo components from combustion-induced pressure fluctuations, iii) providingevidence that efficiency gains comparable to those of CVC over deflagrativecombustion can be realized, and iv) designing an effective one-way intakevalve. This work addresses challenges i)-iii) utilizing computational enginemodels incorporating a quasi-one-dimensional combustor, zero- andtwo-dimensional compressor and turbine plena, and quasi-stationary turbocomponents. Two SEC operational modes are identified which fire at roughly oneand two times the combustors' acoustic frequencies. Results for SEC-driven gasturbines with compressor pressure ratios of 6:1 and 20:1 reveal 1.5-fold meanpressure gains across the combustors. Assuming ideally efficient compressorsand turbines, efficiency gains over engines with deflagration-based combustorsof 30the obtained efficiencies are close to the theoretical Humphrey cycleefficiencies of 54thermodynamic cycle analyses for individual gas parcels suggest that there isroom for further efficiency gains through optimized plenum and combustordesigns.