This paper describes a method for predicting the performance under both turbine inlet steady state and non-steady state flow conditions of a mixed flow turbine used for turbocharged internal combustion engines. The mixed flow turbine steady state performances computed with the steady state performance prediction method are in good agreement with the experimental results obtained in the Imperial College turbocompressor cold air test rig. The unsteady state performance is computed using a one-dimensional model based on the solution of the unsteady one-dimensional flow equations. These equations are solved in the volute by a finite difference method using a four-step explicit Runge—Kutta scheme. The instantaneous volute exit condition is provided by the steady state rotor performance prediction model with the assumption of a quasi-steady state flow in the rotor. The computed instantaneous performances are in reasonable agreement with published experimental data for the same mixed flow turbine. The unsteady flow model is also used to study the effects of the frequency and the amplitude of the pulse on the performances of the mixed flow turbine.

The development of the aerofoil-shaped turbomachine blades is of prime importance for achieving the appropriate deflection of a three dimensional flow through desired angles, to work at the same degree of incidence and thereby providing the required performances for the specific machine. The sensitivity of the rotor to incidence effects and tendency of the flow to separate from one or the other blade surface have given rise to considerations of the optimum incidence angle and cone angle for a mixed inflow turbine by a numerical investigation using the ANSYS-CFX code. In order to keep the rotor in the same casing some geometrical parameters have been hold constant and the Bezier polynomial is used to generate the new shape of the rotor blade when changing the cone angle magnitude.

Summary Because of higher concerns about increasing global warming, energy consumption and reduction of conventional energy resources and growing attention are given to renewable energy and to cross flow turbines such as the Darrieus turbine to harness water energy (water currents, reservoirs, rivers, and oceans). The aim of the experimental investigation presented in this paper is to evaluate the effect of hydro Darrieus turbine blades fixation pitch angle “ig” on its performance. Four main sets of experimental tests were conducted for the same vertical‐axis hydro turbine model (VAHT) with four blade fixation pitch angles (ig = −1.75°, −4.5°, 1.75°, and 4.5°), at various water flow velocities (V = 0.3‐0.64 m/s corresponding to a water free flow Reynolds number of 2.5 × 104 to 4.36 × 104). A comparison between the results of the present work and with those of a previous experimental study for ig = 0° shows that the best performance of the tested turbine is obtained when the blades are set at a pitch angle of 1.75°. In fact, the corresponding optimum mechanical power and power coefficient relative increases are respectively as much as 82% and 67% with respect to ig = 0° at V = 0.37 m/s and as much as 65% and 77% at V = 0.46 m/s. The worst performance is obtained for the negative blades fixation pitch angle of −4.5°; at the water flow velocity of 0.37 m/s, this leads to power, and power coefficient relative decreases respectively about 75% and 81% with respect to the results obtained for ig = 1.75° and respectively about 54% and 68% of those obtained in the previous work for ig = 0°.

The aim of this study is to predict the improvement in film cooling performance over a flat plate through a single row of cylindrical holes with different streamwise angles by using the Ansys CFX software package. In order to improve the film cooling effectiveness, a short crescent-shaped block is placed downstream of a cylindrical cooling hole. The numerical results of the cylindrical hole without the downstream short crescent-shaped block are compared with experimental data.