Andrey Rogalev

Study of design and technology factors influencing gas turbine blade cooling

The knowledge of aerodynamic and thermal parameters of turbulators used in order to design an efficient blade cooling system. However, all experimental tests of the hydraulic and thermal characteristics of the turbulators were conducted on the rectangular shape channels with a strongly defined air flow direction. The actual blades have geometry of the channels that essentially differs from the rectangular shape. Specifically, the air flow in the back cavity of a blade with one and half-pass cooling channel changes its direction throughout the feather height. In most cases the ribs and pins are made with a tilt to the channel walls, which is determined by the moving element design of a mould for the ceramic rod element fabrication. All of the factors described above may result in the blade thermohydraulic model being developed failing to fully simulate the air flow and the heat exchange processes in some sections of the cooling path. Hence, the design temperature field will differ from the temperature field of an actual blade. This article studied the numerical data of design and technology factors influencing heat transfer in the cooling channels. The results obtained showed their substantial impact on the blade cooling efficiency.

Control valves and cascades for the first stages of turbines with ultrasupercritical steam parameters

This paper considers the problems that will unavoidably be encountered in the creation of new-generation turbines operated at ultrasupercritical initial steam parameters, namely, the development of new control and shutoff valves, the reduction of end energy losses in blade cascades and steam leaks in high-pressure cylinders (HPCs), the elimination of effect produced by regenerative steam bleedoffs on the afterextraction stage, the cooling of a blade cascade, etc. Some possible solutions are given for the two first of the listed problems. The conclusion about the need for the transition to new-generation control valves in the development of new advanced steam turbines with ultrasupercritical initial steam parameters has been made. From the viewpoint of their design, the considered new-generation valves differ from the known contemporary constructions by a shaped axially symmetric confusor channel and perforated zones on the streamlined spool surface and the inlet diffuser saddle part. The analysis of the vibration behavior of new-generation valves has demonstrated a decrease in the dynamic loads acting on their stems. To reduce the end energy losses in nozzle or blade cascades with small aspect ratios, it is proposed to use finned shrouds in the interblade channels. The cross section of fins has a triangular profile, and their height must be comparable with the thickness of the boundary layer in the outlet cross section of a cascade and, provisionally, be smaller than 8% of the cascade chord.

Verification of Thermal Models of Internally Cooled Gas Turbine Blades

Numerical simulation of temperature field of cooled turbine blades is a required element of gas turbine engine design process. The verification is usually performed on the basis of results of test of full-size blade prototype on a gas-dynamic test bench. A method of calorimetric measurement in a molten metal thermostat for verification of a thermal model of cooled blade is proposed in this paper. The method allows obtaining local values of heat flux in each point of blade surface within a single experiment. The error of determination of local heat transfer coefficients using this method does not exceed 8% for blades with radial channels. An important feature of the method is that the heat load remains unchanged during the experiment and the blade outer surface temperature equals zinc melting point. The verification of thermal-hydraulic model of high-pressure turbine blade with cooling allowing asymmetrical heat removal from pressure and suction sides was carried out using the developed method. An analysis of heat transfer coefficients confirmed the high level of heat transfer in the leading edge, whose value is comparable with jet impingement heat transfer. The maximum of the heat transfer coefficients is shifted from the critical point of the leading edge to the pressure side.

The boundary layer separation from streamlined surfaces and new ways of its prevention in diffusers

This work provides a detailed analysis of all force conditions acting in the limits of the boundary layer on the moving fluid and gas media, and shows that a value of the transverse gradient of a shear stress δτ/δy, directly on the streamlined surface, is a main condition determining the possibility of attached flow along the streamlined surface in divergent zones. From an analysis of all the forces and their development in the converging flow, an effective way of prevention of the flow separation from streamlined surfaces of the cone-type, ring-type and axial-radial diffusers was developed that provides the flow stabilization in the wide-angle diffusers and multiple reduction of the dynamic load level acting on the walls of the mentioned devices. Results of the CFD-modeling and experimental investigations for flat asymmetric and wide-angle conical diffusers are presented in this paper.

Reduction methods of secondary flow losses in stator blades: numerical and experimental study

This paper examines the perspective design solutions for the secondary flows intensity reduction in the root and peripheral areas of the vane cascade. Increase of the aerodynamic efficiency is achieved by the special finning of internal shroud surface of the vane passage with curvilinear fins having a small height. A study was conducted to analyze the different types of finning on the basis of three-dimensional simulation (CFD). It considers variations with different number, height and shape of used curvilinear fins. In the process of optimization, the best case, which allows to reduce the secondary flow losses by 10-15 %, was obtained. Experimental studies of two vane cascade models were carried out on the aerodynamic test bench. First model was a vane base-type; second model was based on the optimal geometry obtained according to the results of three-dimensional simulation. Experimental studies make possible to confirm the proposed solution efficiency.

High-Temperature Technologies of Electric Energy Production on Steam-Turbine Power Plants

This article considers possible methods to improve economic efficiency of coal-fired plants by means of increase of steam performance upstream of the steam turbine. It gives the methods to increase steam temperature upstream of the turbine by means of heat values of both fossil and hydrogen fuels.

Superpowerful combined cycle power units with one gas turbine

This paper deals with different ways to increase the unit capacity of combined cycle power plants (CCPP) with an in-line equipment layout using a single gas turbine. The transition to a double flow gas turbine using a low-speed low pressure compressor connected with a low-speed steam turbine is a revolutionary way to solve the above problem. The double-shaft compressor is commonly designed with two additional internal bearings and is offered as a solution. The first stages of such a compressor (low pressure compressor (LPC)) connect with the steam turbine, but the second high-pressure group of stages (high-pressure compressor (HPC)) is driven by the gas turbine. So the gas turbine unites a start-up at the base of the HPC. The low pressure compressor and steam turbine can be designed with low revolution speed, which considerably increases air flow through the compressor and leads to an increase in the combined cycle power plant’s power capacity.

Thermodynamical aspects of the passage to hybrid nuclear power plants

This paper deals with a method of efficiency and power capacity for nuclear power plants, with the increase of pressurized water reactors at the expense of the passage to hybrid technologies. The essence of such a passage lies within two types of fuel applications and is realized by outer (in the case of a nuclear steam generating unit) steam superheater usage, which consumes fossil or hydrogen fuel.