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This study utilizes two modern computational fluid dynamics (CFD) software packages (ansys®cfx® and ansys®fluent®) to analyze the basic geometric factors affecting the efficiency of a typical impulse turbine injector. A design of experiments (DOEs) study is used to look at the impact of four primary nozzle and spear design parameters on the injector losses over a range of inlet pressures. Improved injector designs for both solvers are suggested based on the results and comparisons are made. The results for both CFD tools suggest that steeper injector nozzle and spear angles than current literature describes will reduce the losses by up to 0.6%.

The Turgo hydro turbine belongs to the impulse turbines class, along with Pelton and Cross Flow machines, in which the energy exchange is based on the kinetic energy of the water that enters and leaves the turbine at atmospheric pressure. The Turgo impulse turbine was invented and patented by Eric Crewdson, in 1919. The operating range is similar to the Pelton turbine but it is more suitable for medium heads and operates efficiently over a wide range of flow rates (Fig.

This paper uses two modern commercial CFD software packages to compare the performance of a standard and improved impulse turbine injector developed in a previous study. The two injector designs are compared by simulating the 2D axis-symmetric cases as well as full 3D cases including the bend in the branch pipe and the guide vanes. The resulting jet profiles generated by these simulations are used to initialise the inlet conditions for a full Pelton and Turgo runner simulation at different operating conditions in order to assess the impact of the injector design on the performance and efficiency of a real impulse turbine.The results showed that the optimised injector design, with steeper nozzle and spear angles, not only attains higher efficiencies in the 2D and 3D injector simulations, but produces a jet which performs better than the standard design in both the Pelton and the Turgo runner simulations. The result show that the greatest improvement in the hydraulic efficiency occurs within the injector with the improved design showing an increase in efficiency of 0.76% for the Turgo 3D injector and 0.44% for the Pelton 3D injector. The results also show that in the case of the 3D injector, the improved injector geometry produces a jet profile which induces better overall runner performance, giving a 0.5% increase in total hydraulic efficiency for the Pelton case and 0.7% for the Turgo case.