[(Mo,Sn)(Ti,Zr)14]Nb1 serial alloy compositions were designed using a cluster-plus-glue-atom model to receive BCC β-Ti alloys with low Youngs modulus (E) in Ti-based multi-component systems, where the square brackets enclose the coordination polyhedron cluster CN14 of the BCC structure and Nb is the glue atom. These serial alloys were prepared into rods with a diameter of 6 mm by copper-mould suction casting method. XRD and tensile test results indicated that all these alloy series possessed a monolithic BCC structure except [SnTi14]Nb1 and [(Mo0.5Sn0.5)Ti14]Nb1 due to Sn deteriorating BCC structural stability. A combination of Mo0.5Sn0.5 at the cluster center, as well as low-E Nb and Zr in the glue and cluster shell respectively, can reach simultaneously low E and high BCC stability, incarnated in the [(Mo0.5Sn0.5)(Ti13Zr)]Nb1 alloy which has the lowest E of 48 GPa in the suction-cast state.

The flow inside the impeller and diffuser of a turbocharger compressor was analyzed numerically in this paper. The results indicate that the internal flow is disturbed and efficiency is low. There exists a big vortex in the diffuser which dissipates a large amount of energy. Based on the commercial design software, different design parameters were optimized by trial-and-error. Numerical flow analysis results of the final design show that the efficiency is increased by 6.26% and internal flow is improved greatly. It can be concluded that the meridian radius of the impeller flow path has great effect on the compressor performance.

the effect of the interference between the diffuser vanes with the volute tongue was studied in this paper, based on the 3-d model of the residual heat removal pump and the numerical flow analysis platform developed with the commercial CFD software NUMECA. Results indicate that poor matching of the diffuser vanes and the volute may cause serious flow losses. The relative position between the diffuser vanes and the volute was optimized by numerical experiments. Final modifications indicate that the efficiency is increased by 6.4%.

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