High efficiency centrifugal compressor module for smallgas turbine engine

摘要

The context of our invention is the development of a high efficiency centrifugal compressor module with moderate pressure ratio incorporating air intake duct, impeller, vaneless, radial and axial diffusers. The present compressor module is for a small starter unit and the main requirement from such units is to have minimum start timings. These small gas turbine engines should be rotated to their design rpm in the minimum possible time, to assist main engine (engine to be started) with the cranking torque in the least possible time. It is of critical significance to select the impeller material which is governed by the level of stress and deflection at the operating condition. Thus, to design impeller so that higher grade material like titanium can be avoided, limits the impeller exit radius and thus the tip speed. A high efficiency compressor module for the same is developed with an impeller having plurality of the blades. The thickness of each blade increases from tip of the blade towards the hub surface. The blade angle distribution from Leading edge to Trailing edge from HUB to SHROUD of the impeller blade is so optimized that it reduces localized blade loading and also the tendency of flow separation. The blade angle distribution, in context, simultaneously allows efficient transfer of work to the working fluid and also reduces the structural loading (in bending) under hot/ working condition.