Preliminary Mechanical Redesign of an Existing Gas-Turbine Engine to Incorporate a High-Efficiency, Low-Pressure-Ratio, Highly Regenerative Cycle for Marine Applications

摘要

The low-pressure-ratio, highly-regenerative, gas-turbine engine has been proposed as an efficient alternative to other current small-scale marine propulsion systems. This thesis provides a preliminary mechanical redesign of an existing gas-turbine engine to lower the compressor pressure ratio and incorporate a regenerator. One basic design is presented with several alternative turbine modifications. The redesign includes elimination of the second stage of the original two-stage centrifugal compressor, increasing the liner flow area of the existing annular combustor, elimination of the first stage of the three-stage axial turbine, reblading the last two turbine stages, sizing an appropriate regenerator, and designing annular inlet and outlet scrolls to direct gas flow to the regenerator. Due to the simplicity of the original engine and its operating environment (high-altitude turboprop), modification to a regenerative system for marine use appears feasible and attractive. The redesigned engine has a maximum design-point thermal efficiency of 49% with a reduction in power output from the original engine of only 12.5%. The extend of the modifications to the original engine could be reduced somewhat to enhance economic attractiveness at the expense of reduced efficiency or power output.