Design and Numerical Simulation of Radial Inflow Turbine Volute

Abstract

The volute of a radial inflow turbine has to be designed to ensure that the desired rotor inlet conditions like absolute Mach number, flow angle etc. are attained. For the reasonable performance of vaneless volute turbine care has to be taken for reduction in losses at an appropriate flow angle at the rotor inlet, in the direction of volute, whose function is to convert gas energy into kinetic energy and direct the flow towards the rotor inlet at an appropriate flow angle with reduced losses. In literature it was found that the incompressible approaches failed to provide free vortex and uniform flow at rotor inlet for compressible flow regimes. So, this paper describes a non-dimensional design procedure for a vaneless turbine volute for compressible flow regime and investigates design parameters, such as the distribution of area ratio and radius ratio as a function of azimuth angle. The nondimensional design is converted in dimensional form for three different volute cross sections. A commercial computational fluid dynamics code is used to develop numerical models of three different volute cross sections. From the numerical models, losses generation in the different volutes are identified and compared. The maximum pressure loss coefficient for Trapezoidal cross section is 0.1075, for Bezier-trapezoidal cross section is 0.0677 and for circular cross section is 0.0438 near tongue region, which suggested that the circular cross section will give a better efficiency than other types of volute cross sections.

CFD Study of Exhaust Gas Energy Recovery Potential of a Radial Flow Turbine for Electricity Generation

“…The volute section is a critical part of a radial turbine and oftentimes, the geometry of the volute and other elements within it, determines how efficient, the fluid flow and the energy conversion process in the turbine will be. In a radial inflow turbine, the volute has to be carefully designed to ensure that the desired rotor inlet conditions for optimal performance, like the absolute Mach number, flow angle, mass flow parameter (MFP), efficiency and so on, are achieved [24]. The volute determines how fluid is fed into the turbine impeller or rotor.…”

“…Several other authors have also reported on the impact of the volute geometry on the efficiency and other fluid flow characteristics within a turbine. Shah et al, [24], designed and conducted a numerical simulation of radial inflow turbine volute with three different cross-sectionally shaped volutes, using a commercial computational fluid dynamics code, and concluded that based on the maximum pressure-loss coefficient, that the circular cross-section gave the best efficiency compared to the other types of volute crosssections.…”