Detailed Design and Aerodynamic Performance Analysis of a Radial-Inflow Turbine

Abstract

Radial-inflow turbines (RI turbines) are critical components of air cycle machines (ACM), utilized in environment conditioning systems (ECS). In this work, a process is presented for the full design of a radial-inflow turbine, including volute, nozzle blade row and rotor blade row. The preliminary and detailed aerodynamic design approaches are explained in detail. A mean-line (1D) analysis method coupled with the preliminary design is employed to evaluate the aerodynamic performance of the RI turbine. Then, ANSYS CFX is used to perform unsteady 3D simulations of the designed RI turbine at design and off-design conditions to predict the aerodynamic performance of the turbine for future optimization. radius ratio and distribution of rotor-exit tangential velocity. The program was able to compute the basic dimensions of the turbine stage, temperature and pressure at inlet and outlet sections of each component. Rodgers [10] developed an advanced program to design a small, cooled radial turbine, which operated at high inlet turbine temperature. This program was able to determine the rotor blade camber line in addition to the capabilities of the program developed by Glassman. Whitfield [11] presented a non-dimensional approach based on non-dimensional power to minimize Mach number at the rotor inlet and outlet so that the passage losses are reduced. The non-dimensional turbine design can then be transformed to the dimensional design by applying inlet stagnation conditions (total temperature and pressure) and mass flow rate. Ventura et al. [12] also provided an automated mean-line (1D) approach to the preliminary design of RI turbines. Authors used a brute-force search algorithm to select dimensions based on non-dimensional performance and geometry characteristics. Ebaid et al. [13] employed an optimization algorithm during preliminary design to remove selective open parameters such as rotor axial length. They also presented a detailed approach for nozzleless volute design. However, all aforementioned works did not describe an approach to achieve the second step in radial-inflow design. Although commercial software such as ANSYS-Vista RTD and RITAL do not provide any information about the rotor detailed design, stator geometry, stator profile and volute dimensional specifications, designers usually use them for the preliminary design [7,14,15]. In other similar works with preliminary design of the RI turbine, we cannot find a detailed design approach for all components of a typical RI turbine (Volute, stator and rotor) [16][17][18][19][20].In this study, we redesign the radial-inflow turbine applied in the air cycle machines at Amikabir University of Technology to achieve higher efficiency such that the coefficient of performance of ACM is improved. To achieve this goal, first, a preliminary design approach has been developed based on the various available methods. Second, a method is applied to the detailed aerodynamic design of the turbine rotor blades based on Aungier [7] and then the detailed design of volute is est...

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