2208 超小型ガスタービン用ラジアルタービンの要素試作  [in Japanese] Fabrication of Radial Turbine for a Ultra-micro-scale Gas-turbine System  [in Japanese]

Small-scale radial gas turbincs that are composed of a two-dimensional vaned nozzle and a two-dimensional impeller with tip diameter of 40 mm have been designed, fabricated and experimented. The designed pressure ratio, turbine inlet temperature, and mass flow rate are, respectively 2.91,1223K and 30g/s (in one case 19g/s). These turbines are expected to generate an output power approximately of 7 kW at a rotational speed of 2.4-(10)^5rpm and in one case 4 kW at a rotational speed of 1.89×(10)^5rpm. Aerodynamic-performance measurements revealed that a maximum adiabatic-efficiency of over 65% on the total-to-static basis is about 15% lower than that of a conventional three-dimensional radial turbine. From three-dimensional Navier-Stokes computations with Baldwin-Lomax turbulence model, major sources have been quantified from the entropy generation, and therefore they give room for performance improvement; about halves of loss-generation occur at the exducers, and around 40% of losses occur at nozzle trailing edges and suction side of blades.