Colour changing material for the estimation of flue gas radiation on the miniature gas turbine surface

2021 ◽  
pp. 146442072110455
Author(s):  
Mahalingam Arulprakasajothi ◽  
Pegyyem Lokaiah Rupesh ◽  
Hitesh Kumar Rana ◽  
Kariappan Elangovan
Keyword(s):  
Fluid Dynamics ◽  
Temperature Gradient ◽  
Surface Temperature ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Flue Gas ◽  
Dynamics Simulation ◽  
Blade Surface ◽  
Numerical Validation ◽  
Surface Temperature Gradient

The gas turbine is being used in the applications of the aircraft propulsion system and land-based power generating systems more effectively. The manufacturers should optimise the temperature of the gas turbine engine components to enhance the life span of the components. The present research work concentrates on determining the surface temperature gradient on the fabricated turbine blades using a colour changing paint based on temperature attained on the surface. A calibration database has been created, and the surface temperature has been detected based on the available colour contours on the blade surface using human vision. An image processing algorithm has also been proposed for accurate temperature measurement on the blade surface. The obtained surface temperature using colour changing paint multi-colour change 350-8 has been calibrated with the conventional measurement technique IR thermography for experimental validation. A computational fluid dynamics simulation model of the turbine blade has been simulated to predict the surface temperature of blades using analysis systems fluid dynamics for numerical validation. The experimental and numerical validation results have shown a nominal value of error, which proves that the surface temperature gradient can be easily predicted with the help of temperature indicating paint using the proposed algorithm. The study has been extended further to evaluate the amount of emissive power radiated by the flue gas on the turbine blade surface based on the temperature and the wavelength of the colour obtained for the health monitoring of the blade.

The ultra-high efficiency gas turbine engine, UHEGT, Part II: A numerical study on reducing the stator blade surface temperature by indexing fuel injectors and using film cooling

2020 ◽  
pp. 095765092097353
Author(s):  
Seyed M Ghoreyshi ◽  
Meinhard T Schobeiri
Keyword(s):  
Surface Temperature ◽  
Gas Turbine ◽  
Film Cooling ◽  
Total Pressure ◽  
High Efficiency ◽  
Combustion Process ◽  
Blade Surface ◽  
Turbine Engine ◽  
Fuel Injectors ◽  
Stator Blade

In the Ultra-High Efficiency Gas Turbine Engine, UHEGT (introduced in our previous studies) the combustion process is no longer contained in isolation between the compressor and turbine, rather distributed within the axial gaps before each stator row. This technology substantially increases the thermal efficiency of the engine cycle to above 45%, increases power output, and reduces turbine inlet temperature. Since the combustion process is brought into the turbine stages in UHEGT, the stator blades are exposed to high-temperature gases and can be overheated. To address this issue and reduce the temperature on the stator blade surface, two different approaches are investigated in this paper. The first is indexing (clocking) of the fuel injectors (cylindrical tubes extended from hub to shroud), in which the positions of the injectors are adjusted relative to each other and the stator blades. The second is film cooling, in which cooling holes are placed on the blade surface to bring down the temperature via coolant injection. Four configurations are designed and studied via computational fluid dynamics (CFD) to evaluate the effectiveness of the two approaches. Stator blade surface temperature (as the main objective function) along with other performance parameters such as temperature non-uniformity at rotor inlet, total pressure loss over the injectors, and total power production by rotor are evaluated for all configurations. The results show that indexing presents the most promising approach in reducing the stator blade surface temperature while producing the least amount of total pressure loss.

What Controls the Mean East–West Sea Surface Temperature Gradient in the Equatorial Pacific: The Role of Cloud Albedo

2014 ◽  
Vol 27 (7) ◽  
pp. 2757-2778 ◽  
Author(s):  
N. J. Burls ◽  
A. V. Fedorov
Keyword(s):  
Temperature Gradient ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Walker Circulation ◽  
Equatorial Pacific ◽  
Sea Surface ◽  
Sea Surface Temperature Gradient ◽  
The Mean ◽  
East West ◽  
Surface Temperature Gradient

Abstract The mean east–west sea surface temperature gradient along the equator is a key feature of tropical climate. Tightly coupled to the atmospheric Walker circulation and the oceanic east–west thermocline tilt, it effectively defines tropical climate conditions. In the Pacific, its presence permits the El Niño–Southern Oscillation phenomenon. What determines this temperature gradient within the fully coupled ocean–atmosphere system is therefore a central question in climate dynamics, critical for understanding past and future climates. Using a comprehensive coupled model [Community Earth System Model (CESM)], the authors demonstrate how the meridional gradient in cloud albedo between the tropics and midlatitudes (Δα) sets the mean east–west sea surface temperature gradient in the equatorial Pacific. To change Δα in the numerical experiments, the authors change the optical properties of clouds by modifying the atmospheric water path, but only in the shortwave radiation scheme of the model. When Δα is varied from approximately −0.15 to 0.1, the east–west SST contrast in the equatorial Pacific reduces from 7.5°C to less than 1°C and the Walker circulation nearly collapses. These experiments reveal a near-linear dependence between Δα and the zonal temperature gradient, which generally agrees with results from the Coupled Model Intercomparison Project phase 5 (CMIP5) preindustrial control simulations. The authors explain the close relation between the two variables using an energy balance model incorporating the essential dynamics of the warm pool, cold tongue, and Walker circulation complex.

Measurement and Simulation of a Transonic Innovative Cooling System (ICS) for High-Temperature Transonic Gas Turbine Stages

2004 ◽  
Author(s):  
E. Go¨ttlich ◽  
L. Innocenti ◽  
A. Vacca ◽  
W. Sanz ◽  
J. Woisetschla¨ger ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Cooling System ◽  
Leading Edge ◽  
Numerical Comparison ◽  
Blade Surface ◽  
Trailing Edge ◽  
Advantages And Disadvantages

Gas turbine design technology requires the development of transonic turbine stages capable of carrying high stage load and of handling hot gas temperatures at turbine inlet. A reliable cooling system is necessary to cope with shocks emanating from preceding blade rows and impinging on the blade especially in the leading edge region. In order to fulfill these requirements researchers at Graz University of Technology have been working on an Innovative Cooling System (ICS) since 1995. The ICS is able to cover large areas of the blade surface with an effective cooling film and to reduce the metal temperature without a shower head cooling arrangement at the leading edge and any trailing edge cooling air ejection. In this paper the authors present a numerical comparison of the ICS to a conventional modern film cooling system both implemented in the same industrial transonic gas turbine blade. An experimental determination of the adiabatic film cooling effectiveness distribution around the blades surface was necessary for the ICS because of its uncommon design. The measurements were done on a cylindrical blade in a linear cascade arrangement. An infrared camera system was used to determine the effectiveness of this newly designed cooling system by measuring the temperature distribution on the blade surface. Then a numerical simulation of heat transfer and of internal and external cooling for the turbine blade at test rig conditions was performed. The ICS showed a lower outer wall temperature distribution of the blade compared to a standard film cooling system. The heavily loaded leading edge as well as the trailing edge are well cooled. Further conclusions on the advantages and disadvantages of the ICS are drawn.

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