# The Effect of Blade Angle Deviation on Mixed Inflow Turbine Performances
## 4 Conclusions  
A 3D digital model of a mixed-type turbine has been created in this work. Simulation modeling of gas-dynamic and design features of such a turbine has been carried out. By varying the blade deviation angle, some geometric parameters were fixed in order to keep the same rotor casing; several rational geometric shapes of the blade were obtained. It is shown that this approach makes it possible to completely change the three-dimensional shape of the blade and increase the efficiency of the turbine. Geometric tests were carried out at three rotational speeds to demonstrate the effect of deviation blade angle at different machine loads (50%, 75%, and 100%). It has been established that the maximum output work and the resulting power are associated with the highest efficiency for a specific optimal design case of a 100% machine load (deviation blade angle \(-35^{\circ}\)), and they are achieved by increasing the contact surface of the blade with the fluid. It was also remarked a negligible effect of blade deviation angle on power, output work and efficiency for 50% and 75% loads. It was observed that the deviation blade angle is not clear for a load of 50%; the expansion rate is proportional to the increase in the deviation angle for a 100% load; the opposite is just for a 75% load. It has been observed that the static pressure distribution will be more uniform in the case of a 100% load. The variation of the relative Mach number along the axial direction of the flow for different deviation blade angles at different rotational speeds showed that the fluid behaviors in the rotor are the same in the converging-diverging nozzle due to the formation of the boundary layer near the blades at several places. It should be noted that with such a rational turbine geometry, the weight of the rotor increases by only 4.37%, which is quite acceptable. For higher absolute output kinetic energies at deviation blade angles from \(-10^{\circ}\) to \(-20^{\circ}\), it is recommended to use an exhaust diffuser to recover part of it to a larger expansion ratio. The effect of blade deviation angle on mixed flow performance drops sharply starting at \(-20^{\circ}\) at a 100% machine load, so it is recommended to avoid using angles greater than \(-20^{\circ}\) as vane angle values. The developed digital model can also be effectively used at all subsequent stages of the design and manufacture of turbines, including for use in CAD to create 3D models and drawings, in automated control systems to create a processing technology using CNC equipment, as well as to determine the power and the frequency characteristics in other sections of Ansys. It will significantly reduce the time and the cost of creating a turbine. Conceptualization, M.A.C. and M.S. ; methodology, M.A.C. ; software, M.A.C., I.K., I.P. and Y.B. ; validation, S.D., I.P. and V.I. ; formal analysis, S.D. and M.S. ; investigation, M.A.C. and Y.B. ; resources, Y.B., V.I. and M.A.C. ; data curation, V.I. and I.K. ; writing--original draft preparation, M.A.C. and Y.B. ; writing--review and editing, S.D., V.I. and I.P. ; visualization, M.A.C. and Y.B. ; supervision, V.I. and I.K. ; project administration, M.A.C., V.I. and I.K. ; funding acquisition, I.K. and M.S. All authors have read and agreed to the published version of the manuscript. This work has been supported by grant agency VEGA project No. 1/0073/19 and grant agency KEGA project No. 001 ZU-4/2020. Not applicable. The general approach has been partially developed within the research project \"Development of a methodology for optimal design and manufacture highly efficient, highly reliable turbomachines, taking into account various operating modes\" (State reg. no. 0121U107511). The results have been partially obtained within the project \"Fulfillment of tasks of the perspective plan of development of a scientific direction \"Technical sciences\" Sumy State University\" funded by the Ministry of Education and Science of Ukraine (State reg. no. 0121U112684).