mohammad hossein shafiei mayam

In the present work, the effects of the blade installation angle of a two-stage axial turbine on its performance are investigated  numerically. The geometrical specifications of the General Electric MS5001 gas turbine are selected for the study. First, the turbine geometry is created and gridded, and the final model is generated by the combination of the gridded blades. In order to calculate the effect of the wall on the turbulent flow, the Shear Stress Transport (SST) turbulence model is used. First, the acquired results from the studied turbine are compared with the available data from the power plant which showed a good agreement. Then, to investigate the effects of the blade angle on the performance of the turbine, the angle of each row from the four rows of turbine blades is changed in each step, and the obtained results are compared with the results of the turbine original model. Increasing the installation angle of stator blades in the second row and decreasing the installation angle of rotor blades in the second row lead to increasing the produces power and efficiency of the turbine. The acquired results show that the produced power is increased by 4% and the turbine efficiency is increased by 0.87% in the best-optimized arrangement of blades.

Many researchers have experimentally and theoretically studied fresh water productivity in solar stills. In this regard, water preheating can play a noticeable role in enhancing the productivity of solar stills. In the present study, in order to study the effect of water preheating at the inlet of desalination system, a cascade solar still is built and integrated with two different solar collector in separated modes; an evacuated solar collector and a conventional flat plate solar collector. The mentioned solar still includes an external condenser, fin, and internal and external reflectors. It is worth noting that the embedded fins in the water passage are applied to induce hot spots and increase the evaporation rate and fresh water. The experiments were performed in August 2015 and summer 2017. The results showed that the combined desalination system with conventional flat plate collector and evacuated tube collector enhace productivity %60 and %13, respectively. In addition, efficiency of solar still in combination with conventional flat plate collector and evacuated tube collector was %81.8 and %59.1, respectively. The price of produced fresh water of solar still with conventional collector obtained 0.035 $/lit and for solar still with evacuated tube collector was 0.045 $/lit.

In this study Large Eddy Simulation method has been employed in order to investigate the effects of blade rotation direction of downstream turbine in two co-rotating and counter-rotating configurations. The acquired results are in good agreement with presented experimental data in literatures. Counter-rotating configuration is used in order to investigate the effect of blade rotation on the efficiency of downstream wind turbine. The results show that the efficiency of downstream wind turbine is increased about 4 percent without any change in wind farm layout and type of wind turbines. The upstream wind turbine absorbed a portion of wind energy. Hence stream wise velocity is decreased and lateral velocities are increased in downstream direction. The flow behind the upstream turbine is rotated in same direction with downstream turbine in a counter-rotating configuration. This is why the efficiency of downstream turbine is increased in a counter-rotating configuration. The results of the present study show that streamwise velocity profile is almost identical in both configurations¡ while¡ lateral velocities are changed considerably. In other words¡ a better efficiency of wind farm could be due to the lateral velocities. Hence¡ the efficiency of wind farm could be increased by decreasing the distance between two consecutive wind turbines in a counter-rotating configuration.