Some helicopter and other engines have been shown in studies to be amenable to conversion to a low-pressure-ratio highly regenerated cycle. Typically the high-pressure compressor and high-pressure turbine would be removed, and shaft and ducting modifications would be made to introduce high-effectiveness rotary ceramic-honeycomb regenerators. In one case examined the low-pressure turbine could be used with slight modification; in others there would have to be reblading of the turbine stages and the manufacture of new shrouds. In another case the existing combustor could be used with little modification; in others new combustors would be required. Despite the extent of the modifications, the resulting high-efficiency performance over a large part of the power range and presumably relatively low capital and development costs could make this an attractive concept.

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