The pressure, velocity and temperature distribution in the rotorblade surface are illustrated in Fig. 16. It can be seen from Fig. 16(a)that the static pressure in the blade pressure surface gradually decreasesfrom the leading edge to the trailing edge of the blade. At the 90% ofblade height of the leading edge, part of the isobar is bent to form asmall recirculation zone. With the streamwise being about 30% to 45%and the blade height being 70%, there is a range of low pressure regions.The isobars are generally evenly distributed, but they arestrongly bent near the tip of the blade, causing flow losses. It can beseen from Fig. 16(b) that the static pressure in the suction surfacegradually decreases along the streamwise. At 80% of the blade height ofthe blade trailing edge, there is a local low pressure region and thedistribution of isobars is complicated. In view of the pressure surfaceand suction surface of the blade, the effect of the wall surface on theflow characteristics is greater, and the overall static pressure decreaseswith the decrease of the blade height. The velocity distribution in thepressure surface, and the flow velocity gradually decreases from theleading edge to the trailing edge of the blade, as shown in Fig. 16(c). Atthe blade inlet, the isovelocity line is distributed more evenly, while atthe 20% of blade height of the trailing edge, there is a local low-speedzone. The velocity gradually decreases along the streamwise, as shownin Fig. 16(d). The isovelocity line is curved to form a small low velocityregion at the trailing edge of the blade. At the same time, the velocitynear the hub is obviously lower than the number near the shroud. Thevelocity distribution on the blade is relatively uniform, and the workingfluid flow state is better. It can be seen from Fig. 16(e) that the temperaturein the blade pressure surface gradually decreases from theleading edge to the trailing edge of the blade. The temperature drop ofthe former changes markedly, while the temperature gradient of thelatter is smaller, and the isotherm distribution of the blade inlet is moreuniform. Overall, the blade is featured with excellent flow properties,but there is a certain flow loss at the trailing edge. In the future designof the rotor, some attention should be paid to the improvement of thetrailing edge shape of the blade.4.6. Profile optimization of the rotor bladeIn the design of the rotor, the value of t is given empirically ingeneral, so there is some uncertainty. Therefore, it is necessary to findthe optimal parabolic index t to make the flow state inside the rotor isoptimal. By adjusting the value of the parabolic index t, different valuesof zm are obtained, and the numerical calculation of the flow field in therotor is performed. The results are shown in Table 6.As can be seen from Table 5, the axial length of the rotor increasesas the parabolic index t becomes larger. The rotor efficiency increaseswith the parabolic index t, and the impeller efficiency reaches themaximum when the optimal value is t=1.95. The efficiency of therotor increases firstly and then decreases with the increase of theparabolic index t. When the optimal value is 1.95, the rotor efficiencyreaches the maximum.The velocity vector of 50% of the blade height flow surface is shownin Fig. 17. The comparison shows that there is an enormous differencebetween the flows of working fluid before and after optimization. In theflow passage before optimization, the working fluid moves substantiallyalong the flow guiding direction after passing through 50% of the flowpassage. The range of vortex near the optimized rotor inlet is significantlysmaller than that of the original rotor, and the working fluidflows along the guiding direction at 35% of the flow passage. At 70% ofthe flow passage, the optimized velocity vector distribution is moreuniform, indicating that the flow state of the main flow in the flowpassage is good, and the expansion process can be successfully realizedfor most of the working fluid.The velocity vector of 50% of the blade height rotor inlet is shownin Fig. 18. There is a distinct bending phenomenon in the inlet velocityvector before optimization, but the optimized inlet velocity vectordistribution is more uniform. It is concluded that the optimized rotorinlet flow performance is improved and the working fluid is substantiallyunaffected by the rotor inlet vortex.