Ground Turbine Engines: Which Cycle is Best?

Current component configuration conventions for U.S. Army ground vehicle gas turbine engines place the heat exchanger downstream of the power turbine, especially in heavy duty applications. However, a gas turbine with the heat exchanger upstream of the power turbine has been proposed by Shapiro et al of Bet-Shemesh Engines, Ltd. Indeed, a U.S. patent (No. 4,506,502) was issued in 1985 for this configuration, and a paper describing this cycle was published in 1990. Claimed benefits are reduced specific fuel consumption (SFC) and high power density. In general, Shapiro used relatively low pressure ratios and slightly low component efficiencies in his analyses to support these claims. This paper describes the results of an in-depth cycle analysis study of this proposed configuration with more current component performances and higher pressure ratios.