M-DOT proposes to study application of a proprietary rotary expander as a quasi-Constant-Volume Combustor (CVC) in a gas turbine. Whereas CVC has been explored as a topping element (to increase max cycle pressure) within the Brayton cycle, it has generally involved reciprocating piston or wave rotor embodiments. The rotary expander should provide constant-volume pressure rise combustion with smooth mechanical operation. In addition, the expander can be self propelling through proper timing of the burning process. Challenges include selection of structural materials to take the high operating temperatures, minimizing thermal distortion and leakage, developing optimum timed injection of fuel to maximize efficiency and provide positive drive torque, and integration of the CVC burner into the gas turbine such that performance of the compressor and turbine are not compromised. In Phase I, a cycle study will be conducted to estimate benefits in a 1600 HP class turboshaft. Initial boundary conditions will be basis for a combustion analysis by Daniel Paxson at NASA GRC to generate pressure and temperature data for use in a CVC/Brayton cycle study. At Phase I conclusion, a preliminary design will exist as basis for Phase-II design, fabrication and testing of a rotary CVC
