A Unified Approach to the One-Dimensional Analysis and Design of Radial and Mixed Flow Turbines

Abstract

A unified one-dimensional analysis and design procedure for radial and mixed flow turbines is presented. This procedure considers the flow in all of the turbine components, including the inlet volute, nozzled or nozzleless inlet duct, rotor and exit duct. Losses are included for each component; in the stationary ducts, friction is the main loss mechanism, and in the rotor skin friction, clearance and disk friction are considered separately. Incidence losses at entry to both nozzle and rotor are calculated using one of two loss models. For each component, the procedure is to combine the equations of continuity, momentum, energy, and entropy into a single dimensionless expression for the Mach number at exit. This approach has proved possible under a wide variety of circumstances, and with its flexibility and ease of programming for solution by computer would seem to have many applications in one-dimensional ducted flow. The predicted performance of a radial inflow nozzleless turbine is compared with experimental results. The comparison is considered to be sufficiently good to confirm the validity of this approach. The results obtained with each of the two incidence loss models are compared. Each model is found to have its own advantages and fields of application.