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

Asymmetric Method of Heat Transfer Intensification in Radial Channels of Gas Turbine Blades

Loop and semi-loop cooling schemes are widely used for the high-temperature gas turbine blades. In such schemes, the mid-chord airfoil parts are traditionally cooled by radial channels with ribbed walls. The blades with a small specific span, or “short” blades, have different heat flux amounts on pressure and suction sides, which results in a temperature difference in these sides of 100–150 °K. This difference causes thermal stresses and reduces the long-term strength margins. This paper presents a new method of heat transfer intensification in the ribbed radial cooling channels. The method is based on air streams’ injection through holes in the ribs that split channels. The streams are directed along the walls into the stagnation zones behind the ribs. The results of a 3D coolant flow simulation with ANSYS CFX code show the influence of the geometry parameters upon the channel heat transfer asymmetry. In the Reynolds number within a range of 6000–20,000, the method provides the heat transfer augmentation difference by up to 40% on the opposite channel walls. Test results presented in the criteria relations form allow for the calculation of mean the heat transfer coefficient along the channel length

Computer Flow Simulation and Verification for Turbine Blade Channel Formed by the C-90-22 A Profile

Currently, software products for numerical simulation of fluid dynamics processes (Ansys, Star CCM+, Comsol) are widely used in the power engineering industry when designing new equipment. However, computer simulation methods embedded in proprietary software products make specialists choose grid settings, boundary conditions, and a solver providing the minimal deviation from experimental data with the maximal calculation speed. This paper analyzes the influence of the main grid settings and boundary conditions in the Ansys software package on the error in the computer simulation of flows in standard elements of power equipment and gives recommendations for their optimal choice. As standard elements were considered blade turbine channels formed by C-90-22 A profiles

Research and Development of Hybrid Power Units Heat Flow Diagrams with Cooled High-Temperature Steam Turbines

Fossil fuel thermal power plants account for almost 60% of Russian electricity and heat. Steam turbine units make almost 80% of this amount. The main method for steam turbine unit efficiency improvement is the increase in the initial steam parameters’ temperature and pressure. This reduces fossil fuel consumption and harmful emissions but requires the application of heat-resistant steel. The improvement in steel’s heat resistance leads to a non-linear price increase, and the larger the temperature increase, the more the steel costs. One of the methods of improving efficiency without a significant increase in the capital cost of equipment is an external combustion chamber. These allow an increase in the steam temperature outside the boiler without the need to use heat-resistant alloys for boiler superheaters and steam pipelines between the boiler and the steam turbine. The most promising is hydrogen–oxygen combustion chambers, which produce steam with high purity and parameters. To reduce the cost of high-temperature steam turbines, it is possible to use a cooling system with the supply of a steam coolant to the most thermally stressed elements. According to the calculations, the efficiency reduction of a power unit due to the turbine cooling is 0.6–1.27%. The steam superheating up to 720 °C in external combustion chambers instead of a boiler unit improves the unit efficiency by 0.27%. At the initial steam temperatures of 800 °C, 850 °C, and 900 °C, the unit efficiency reduction caused by cooling is 4.09–5.68%, 7.47–9.73%, and 8.28–10.04%, respectively