Performance investigations of cross flow hydro turbine with the variation of blade and nozzle entry arc angle

Mistreatment of small hydropower sources requires the use of small turbines that combine efficiency and economy which can suitably provide the power requirements of rural and small societies. In this context, the cross flow hydro turbines are extensively used due to their simpler in design, ease of maintenance, low initial cost. Although the cross flow hydro turbine has moderated efficiency, but it has operated at low head and discharge. Hence, the objective of the present investigation is to increase the efficiency of a cross flow hydro turbine with the geometric modification. In the present study, the numerical investigation of cross flow hydro turbine has been carried out using multi-physics finite volume solver in ANSYS FLUENT. The three dimensional unsteady simulations have been conducted using shear stress transport k-omega turbulence model. The performance of cross flow hydro turbine has been investigated by changing the inlet blade angle from 5 degrees to 40 degrees and nozzle entry arc angle from 65 degrees to 85 degrees with the number of blades being 20. The rotational speed of the turbine has been varied from 200 rpm to 800 rpm. The total pressure and velocity field have been examined to evaluate the performance coefficients. From the unsteady results, the maximum efficiency has been found at the inlet blade angle, 5 degrees and nozzle entry arc angle, 65 degrees with the runner rotational speed of 600 rpm. However, with the consideration of the manufacturing feasibility inlet blade angle and nozzle entry arc angle have been considered as 10 degrees and 65 degrees respectively to be the most promising design configuration. The effect of temperature of the flowing water on performance of the turbine also has been studied. The maximum efficiency at inlet blade angle, 10 degrees has been found to be 93.8% at 600 rpm. By incorporating the nozzle entry arc angle, maximum efficiency has been found to be 97.8% at nozzle entry arc angle, 65 degrees with rotational speed 600 rpm and inlet blade angle, 10 degrees. The efficiency of the current design configuration has been found 20% higher compare to the existing model.