# Potentials for Pressure Gain Combustion in Advanced Gas Turbine Cycles
## 1 Introduction
All have already been used in steady-state zero-dimensional gas turbine performance simulations. Therein, it was already assumed that only a part of the total kinetic energy during the exhaust phase is available for work transfer in the turbine [14]. Nevertheless, the models' performances deviate from each other [19]. This can be explained by applied simplification and different underlying technical realization of PGC (wave rotor, shockless explosion combustion, pulsed detonation combustion, radial detonation combustion). Individual combustor models were investigated in a gas turbine engine from a thermodynamic perspective such as in [20]. Studies on the integration into a gas turbine using realistic side conditions were performed by [1; 21; 22; 23]. Complete gas turbine optimizations regarding thermal efficiency for various combustor models and their comparison under realistic constraints were published by this author in [19]. This work was further extended regarding advanced gas turbine cycles. The use of PGC also affects the secondary air system (SAS) of the gas turbine. Among others, the SAS supplies the turbine blades with cooling air. In conventional gas turbines, the highest pressure is at the compressor outlet, where cold air enters the SAS. The pressure difference between the turbine inlet and compressor outlet caused by the pressure loss across the combustor drives cold air to the turbine blades through the SAS. This is no longer possible with PGC. A SAS compressor is required to overcome the pressure gain in the combustor. This compressor power requirement can amount to 5% of the gas turbine outlet power, thereby reducing thermal efficiency [19]. Therefore, the potential analysis for PGC must take the SAS into account, in order to capture the main effects on the design and thermal efficiency of the engine. The modeling of heat exchangers used for intercooling and recuperation is well researched. While applications in stationary gas turbines are available, they are still being developed for aero engines [24; 25; 26]. For this paper, four different gas turbine models were set up in the gas turbine performance code GTlab-Performance [27]. The four setups are a conventional simple, an intercooled, a recuperated, and a combined intercooled-recuperated gas turbine. Each setup is simulated with PGC models from the literature (15; 19; 28). The latter was created in order to match the published CFD data of (9). For this model, an optimistic and pessimistic version are included. For each setup, a cycle optimization study is performed. The optimization identifies optima with respect to thermal efficiency at a constant blade material temperature and power output. To better understand the limitation of blade temperature constraints, three different temperatures are analyzed. The optimizer varies compressor pressure ratios and engine mass flow. Constraints are used in the optimization, in order to account for real design limitations. The optimized cycle designs are compared to each other, and sensitivity studies will be presented at the point of optimal configuration.