9.D1 Perform the preliminary design of the turbomachinery for a turbojet engine having a thrust of 25,000 lbf at sea-level static conditions. Based on polytropic efficiencies of 0.9 for both compressor and turbine, the engineers in the engine cycle analysis group have determined the compressor and turbine inlet and exit conditions for a range of compressor pressure ratios that will give the required engine thrust. The results of their analysis are presented in Table P9.D1. Note that the mass flow rate through the compressor and turbine decreases with increasing compressor pressure ratio. To minimize on engine weight, it is desirable to have the maximum compressor pressure that can be driven by a single-stage turbine with exit guide vanes. The number of compressor stages depends on both the compressor design and the turbine design. As you can see, there are many sets of compressor/turbine designs that meet the thrust need; however, some of the designs cannot be done with one turbine stage or may be too large (high mass flow rate). Data for other compressor pressure ratios between 7 and 13 not listed in the table can be obtained by interpolation.