Papers by Keyword: Aerodynamic Losses

Abstract: Incidence can significantly affect turbine cascade aerodynamic losses, including profile, secondary and tip-clearance losses. In previous works, correlations for these losses were developed on a convention that the whole cascade has a universal incidence angle. But in reality, there exist exceptional situations when a turbine disk is inclined to its design position. In such cases, the incidence varies with the location of blade on the circumference, leading to loss deviation from its design value. The present paper is motivated to work out new correlations for the profile losses with turbine disk inclinations and examine the effects of turbine disk inclination. Based on the state-of-the-art works, new correlations are developed to take into account the incidence variation by redefining the inlet flow angle in terms of turbine disk inclination angle and location angle of blade on turbine disk circumference. The effects of turbine disk inclination on profile losses were examined through numerical simulations. It is concluded that the turbine disk inclination has considerable influences on the profile losses of turbine cascade.

Abstract: Turbine cascade aerodynamic losses are heavily related to incidence. Conventional researches have been focused on a single blade row upon the convention that the whole turbine cascade has a universal incidence for all blades on the cascade and accordingly the overall aerodynamic loss of the cascade is the same as a single blade row. However, there are exceptional situations in engineering practice that each blade of a turbine cascade has a different incidence. When a turbine disk is inclined to its design position due to manufacturing errors and/or operating malfunctions, the incidence for a blade on the cascade varies along the circumference of the turbine disk. For such case, the conventional research conclusions are no longer adequate. The present paper is motivated to extend the conventional researches to account for such case. Based on the-state-of-the-art works in this field, new sophisticated correlations for turbine cascade aerodynamic losses were developed to cope with the problems with turbine disk inclination. Numerical simulations were performed to examine the effects of turbine disk inclination on the aerodynamic losses. Beneficial conclusions and remarks are given in the end.

Abstract: A numerical simulation of a flow passing throw two NACA 0012 airfoils is presented in this paper. Aerodynamics, drag forces, and pressure drop is quantified when both profiles are axially aligned and then when one of them is vertically displaced. NUMECA code and Spalart-Allmaras turbulence model were used for this purpose. The results showed that aerodynamic losses are present in both profiles, meaning that the presence of the back profile plays an important role in the aerodynamic behavior of the frontal profile.