To ensure uniform flow, tests were carried out to determine the ideal shape of the exhaust diffuser (Figure 8).

　

Figure 7 Core of Recuperator

Figure 8 Recuperator inlet flow test

　

5. 3) Research on High-efficiency Compressor

Compressor efficiency has a large influence on the overall efficiency of gas turbines. To improve the overall thermal efficiency the compressor should be as efficient as possible. Most gas turbines in the 2-MW class use simple radial compressors, however, to achieve maximum efficiency the SMGT uses an axial compressor for the low-pressure stages and a radial compressor for the high-pressure stage.

In developing the compressor, CFD is used to conduct cascade flow simulations and analyze performance. Performance tests are also being conducted on the individual compressors and on the combined unit (Figures 9, 10).

Although experiments are still underway, target efficiencies for some of individual compressors have been reached.

In addition, research was performed to determine the ideal shape of the inlet casing in order to minimize loss and ensure uniform flow distribution at the compressor inlet. Research using rotary cascade tests to determine the ideal cascade for the first stage of the axial compressor, in which mach numbers are highest, was also performed (Figure 11). The results of these tests are being incorporated into the compressor's design.

　

Figure 9 Tested axial compressor

Figure 10 Tested compressors

Figure 11 Flow test for inlet casing

　

5.4) Research on Cooled Blades

Advances in heat-resisting materials and blade cooling technologies have resulted in yearly increases in turbine inlet temperature (TIT).

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