The Cross-flow hydro turbine is a suitable choice for low and medium head due to its simplicity in design, low-cost construction and efficiency close to maximum efficiency in off-design conditions. In this study, a method was proposed to design a cross-flow hydro turbine with a specific head and flow rate, based on that a turbine was designed with head, flow rate and efficiency are 10 m, 0.041 m3/s and 67% respectively. The model has been implemented in the Ansys Fluent software in two dimensions and steady for two phases, water and air. One of the aims of this study was to parametric study of a turbine to achieve the possible maximum efficiency; For this purpose, 6 different geometric parameters and rotational speed were studied. Screening was used to eva‎luate the effectiveness of each parameter, which was found to affect all six parameters in the turbine efficiency, and using the Box-Behnken response surface method,49 different geometries were defined to determine the effect of each parameter and the possibility of optimizing it. After simulating 49 different modes, the best geometry was found to have the highest efficiency, according to which the efficiency value increased by 16% and reached to 78%. The use of the response surface method to the optimize geometry of turbine was used for the first time in this research and had a proper result. When the inlet flow-rate of the turbine decreases from its design value, the efficiency value also decreases. In previous studies, it was stated that using a slider can have an efficiency close to the maximum efficiency at off-design conditions. The slider is a section of circle that rotates to change the size of the rotor input arc and the nozzle height. A slider is a solid piece that is placed in front of a stream of water and its thickness must be such that it can withstand the stresses applied to it. In recent studies, only the presence of sliders was studied and the effect of its thickness on turbine performance was not investigated. In this research, the slider thickness was equal to 3, 5 and 8 mm and in cases where the ratio of the input arc to the optimized input arc was equal to 0.25, 0.5 and 0.75, it was found that using the slider with 2 mm thickness at about 25% of the design flow, the turbine still operates at its maximum efficiency. As the slider thickness increases, the efficiency of the turbine decreases slightly, but by using a thickness of 8 mm in a situation where the ratio of the optimized inlet arc to the inlet arc is 0.25, the amount of efficiency is almost zero, because the water inlet flow due to the high thickness of the slider was zero. Therefore, it was found that the most suitable slider thickness is the minimum thickness that can withstand the stresses applied to it. In recent studies, only the effect of using a slider in the simulation has been studied and the movement mechanism and its construction have not been investigated. In the present study, two slider movement mechanisms were designed and modeled with SolidWorks software. In the first design, two knobs connected to the slider on both sides of the turbine were used to rotate the slider. By changing the inlet flow, the operator rotates the slider with two knobs and puts it in a new position. The second design is a more comprehensive and complex design in which the rotation is transmitted to the slider by using a gear and the operator is not in direct contact with the turbine body, which has much better conditions in terms of technology and safety. Finally, a sample of the designed turbine with a slider and movement mechanism of the first design was built and the equipment needed to test was examined. The pump was connected to the turbine inlet and the fluid flow hited the turbine blades after passing through the nozzle, causing the shaft connected to the rotor to rotate. The rotation of the rotor shaft was transferred to the generator shaft by using the coupling, generating electrical energy.

ابراهيم شيراني، محمدرضا توكلي

مهدي دادخواه

مهدي نيلي احمدآبادي، احمدرضا پيشه ور