TY - GEN A1 - Klein, Rupert A1 - Nadolski, Maikel A1 - Zenker, Christian A1 - Oevermann, Michael A1 - Paschereit, Christian Oliver T1 - Pressure gain combustion for gas turbines : analysis of a fully coupled engine model T2 - Journal of Engineering for Gas Turbines and Power N2 - The “Shockless Explosion Combustion” (SEC) concept for gas turbine combustors, introduced in 2014, approximates constant volume combustion (CVC) by harnessing acoustic confinement of auto-igniting gas packets. The resulting pressure waves simultaneously transmit combustion energy to a turbine plenum and facilitate the combustor's recharging against an average pressure gain. Challenges in actualizing an SEC-driven gas turbine include (i) the creation of charge stratifications for nearly homogeneous auto-ignition, (ii) protecting the turbocomponents from combustion-induced pressure fluctuations, (iii) providing evidence that efficiency gains comparable to those of CVC over deflagrative combustion can be realized, and (iv) designing an effective one-way intake valve. This work addresses challenges (i)–(iii) utilizing computational engine models incorporating a quasi-one-dimensional combustor, zero- and two-dimensional (2D) compressor and turbine plena, and quasi-stationary turbocomponents. Two SEC operational modes are identified which fire at roughly one and two times the combustors' acoustic frequencies. Results for SEC-driven gas turbines with compressor pressure ratios of 6:1 and 20:1 reveal 1.5-fold mean pressure gains across the combustors. Assuming ideally efficient compressors and turbines, efficiency gains over engines with deflagration-based combustors of 30% and 18% are realized, respectively. With absolute values of 52% and 66%, the obtained efficiencies are close to the theoretical Humphrey cycle efficiencies of 54% and 65% for the mentioned precompression ratios. Detailed thermodynamic cycle analyses for individual gas parcels suggest that there is room for further efficiency gains through optimized plenum and combustor designs. Y1 - 2024 U6 - https://doi.org/10.1115/1.4066348 SN - 0742-4795 VL - 147 IS - 2 PB - ASME International ER - TY - GEN A1 - Klein, Marten A1 - Zenker, Christian A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Stochastic modeling of multi-stream mixing based on one-dimensional turbulence T2 - 77th Annual Meeting of the Division of Fluid Dynamics N2 - Measurements of multiple scalar mixing in a turbulent jet show a strong location dependence of the scalar fluctuations and mixing processes. Mixing is quantitatively described by the state space of scalar fluctuations in terms of a joint probability density function (JPDF). The JPDF evolves in the downstream and radial directions and has non-Gaussian shape which is a burden for mixing modeling since factoring into marginal distribution functions is not permissible. Stochastic simulations based on one-dimensional turbulence (ODT) are able to reasonably reproduce the JPDF and its spatial evolution by a parabolic marching problem that circumvents constraints of the underlying elliptic problem. The model reproduces the inertial-advective range (exponent -5/3) and predicts the emergence of the viscous-advective range (exponent -1) at higher wavenumbers as the Schmidt number increases. The model offers full-scale resolution at affordable cost providing means to reasonably capture state-space statistics of turbulent mixing. KW - turbulent mixing KW - one-dimensional turbulence KW - coaxial jet KW - multi-stream mixing Y1 - 2024 UR - https://meetings.aps.org/Meeting/DFD24/Session/ZC40.4 PB - American Physical Society ER -