numerical flow simulation

In this paper, a numerical study of the overall performance and flow structure in an axial turbine and the effect of a film cooling on it are discussed. For this purpose, two-stage axial turbine is simulated and numerically analyzed using the ANSYS-CFX commercial software. Various analyzes have shown that the rate of blowing ratio (B.R) equaled 0.82 and the velocity ratio (V.R) equal to 0.4 with a 30 degree jet angle is suitable for cooling holes. Of course, because of the high importance of leading edge and coolant inject to the stagnation region, as well as increasing the temperature at the pressure side relative to the suction side, there is a higher flow rate for cooling in these areas. The study of the turbine performance curve shows a slight reduction in the pressure ratio and efficiency due to the application of cooling, which can be compensated by the possibility of increasing the inlet temperature. The streamlines around the blade provide a layer of flow with low temperatures, which is an obstacle between the hot flow and the blade surface. The application of cooling reduces the temperature of the pressure and suction surfaces of the blade at about 300 ° C and the temperature of the front surface of the blade is about 200 °. Investigating the radial and axial variations of the thermodynamic parameters indicates that, by applying the cooling, the mach number and total temperature of the flow at inlet and outlet are reduced and the pressure drop increases.

In this article, a numerical study of the effect of splitter plates located on the wake zone of a square cylinder on vortex formation control and aerodynamic noise reduction is presented. The flow is assumed to be unsteady and is simulated using the URANS equations and applying the turbulence model $K-omega-SST$. Aerodynamic noise calculations are carried out by the use of lighthill analogy. For this purpose, a cylinder with a square cross-section (D = 10 mm) has been used and splitters are assumed to have a constant thickness of 2 mm with different lengths. In order to verify the numerical results, the sound pressure level obtained in different situations is compared with the experimental results, and good agreement is observed. The significant reduction of the level of sound pressure of 15% and the reduction of fluctuations with the increase of the Wake area, as well as the reduction of aerodynamic forces by applying splitter, are the results of this study. By applying a splitter with a length equal to the cylinder side, the difference in forward and backward pressure of the intermediate pressure decreases by about 40%, which results in a decrease of about 16% in the averaged drag. In this case, the Reynolds stress is reduced by about 60% as well as the pressure fluctuations by about 50%. The observation of the structure of the flow indicates that the splitter application is prevented from moving the fluid into the inner surface of the shear layers detached by the downstream splitter. The observation of the structure of the flow indicates that the splitter application is prevented from moving the fluid into the inner surface of the shear layers detached by the downstream spinner. Investigating the details of the unsteady flow structure shows that fluctuations in flow and aerodynamic forces have been reduced due to a longitudinal increase in the wake zone.