抄録
Supersonic turbine for a rocket is sometimes designed as a partial admission turbine. However, few studies dealing with the partial admission turbine have been conducted in the past. So, there are a lot of unknown flow patterns and phenomena. This study focuses on nozzle admission layout and its influences on turbine flow pattern, loss production and efficiency. Two nozzle closing ways, (a): nozzle upstream closing, (b): block closing, are simulated by two dimensional unsteady CFD analysis. Different flow pattern and entropy production appear between (a) and (b) at 1^<st> stage behind of the nozzle closed sector. In the case (a), strong mixings are caused at closed nozzle passage outlet and closed sector end side. These mixings are due to velocity difference between high velocity circumferential flow and low velocity gas existing closed nozzle passages and high velocity jet from nozzle opened sector and low velocity gas at the end of nozzle closed sector. In contrast, in the case (b), these velocity differences do not appear and entropy production is low compare with case (a). As a result, turbine efficiency is about 1.7% higher in the case (b) than in the case (a).
