The results of the numerical analysis of the flow capacity and other parameters at the different turbine vanes are presented in this paper. Two plane cascades with the same geometrical throat but with a different shape of suction surface have been investigated by means of the 2D Navier-Stokes code [1]. Stacked with these profiles two vane rows with tip meridional opening have been investigated by means of the 3D Euler code [2] and the 3D Navier-Stokes code [3]. The numerical investigation of two full-scale annular vane rows is confirmed by experimental mass flow performance, obtained in a range of exit isentropic Mach number on the mean diameter from Ma2 is = 0.7 to Ma2 is = 1.3.

A significant part of the overall loss in modern gas turbines is the trailing edge loss. This loss is, more strongly than other constituents, affected by operation, because the trailing edge can significantly change its shape due to degradation. Also by manufacturing of new parts and reconditioning the same tolerances as in other parts of blade lead to higher deviations of aerodynamic characteristics. Therefore the understanding of trailing edge loss generation mechanisms is of utmost importance for a sound blade design. In this work the results of combined experimental and numerical investigation of the trailing edge impact on the transonic cooled blade loss are presented. This study comprises the investigation of the unguided flow angle and the trailing edge shape on the profile losses and a base pressure. The unguided flow angle characterizes the curvature distribution on the aerofoil suction side. The numerical and experimental investigation of transonic cooled turbine cascades have shown that the increase of the unguided flow angle results in loss reduction due to increase of the base pressure downstream of the trailing edge. At the same time the deviation of the trailing edge from a round shape has detrimental effect on performance and conducted investigations allow quantification of this effect. The measurements were performed in a transonic wind tunnel and numerical simulations were done using in-house 2D Navier-Stokes code. The comparison of calculations with measurements showed that they are in reasonable agreement. The validated numerical procedure has been used for demonstration of possibility to reduce loss in aerofoil with thick trailing edge by tuning of the unguided flow angle. The use of the thick trailing edges at HP cooled turbines reduces restriction on tolerances, improves of manufacturability and reduces cost.

The aerodynamic loss due to tip leakage vortex of rotor blades represents a significant part of viscous losses in axial flow turbines. The mixing of leakage flow with the main rotor passage flow causes losses and reduces turbine stage efficiency. Many measures have been proposed to reduce the loss in the tip clearance area. In this paper the reduction of the tip clearance loss due to changes made to the blade tip section profile is presented. The blade tip profile was modified to decrease the pressure gradient between pressure surface and suction surface. This approach allows the reduction of tip leakage and tip vortex strength and consequently the reduction of tip clearance losses. A 3D Navier-Stokes solver with q-ω turbulence model is used to analyze the flow in the turbine with various tip section profiles. Test data of three single-stage experimental turbines have been used to validate analytical predictions: • Highly loaded turbine stage with a pressure ratio π0T = 3.2 and reaction degree ρmean = 0.5. • Two turbines with a pressure ratio π0T = 3.9. (One with high degree of reaction ρmean = 0.55; the other with low degree of reaction ρmean = 0.26). The numerical investigation of the influence of various tip section profiles on stage efficiency was carried out in the range of relative tip clearance 0.5%–2.4% with the objective of a decreasing the influence of the tip clearance on the stage efficiency.

The aero-redesign of a 50 Hz Gas Turbine GT13D3A is presented. The modifications enabling performance improvements are described, and the aero-design process is briefly discussed as well. The aerodynamic characteristics of an upgraded turbine (GT13DM) are compared with the original design (GT13D3A) and with the measurements in the field. The measurements confirmed the expected performance improvement.

The paper presents the detail investigation of temperature field evolution through multistage cooled turbines. An investigation bases on simple enough numerical simulation and allows for transient, heat transfer, viscous and some other important effects on temperature field transformation. Herewith the special test data for a number of cooled turbines are used. The developed numerical code has the following peculiarities: - a time-marching method for the unsteady Euler equation system; - a special algorithm of flow parameters averaging in mixing planes in the middle of axial gaps; - a monotone implicit scheme of second or third order accuracy in space and time. The code has been used for a numerical study of the flow pattern in a number of multistage aviation and industrial turbines. The described simulation demonstrates satisfactory correlation between the numerical and experimental data for temperature gradient attenuation in the flowpath of investigated cooled turbines.