scholarly journals FEATURES OF ORGANIZATION OF FILM COOLING OF HIGH TEMPERATURE GAS TURBINES BLADES

2017 ◽  
Vol 39 (4) ◽  
pp. 11-20
Author(s):  
A. A. Khalatov ◽  
A. S. Kovalenko ◽  
S. B. Reznik
Keyword(s):  
High Temperature ◽  
Film Cooling ◽  
Gas Turbines ◽  
Small Dimension ◽  
Cooling Efficiency ◽  
Local Distribution ◽  
Cooling Air ◽  
High Temperature Gas

The features of the release of the cooling air in the interscapular channel high temperature gas turbines at the film cooling are considered. Possibilities of its local distribution on contour of an entrance edge of the perforated blades are investigated. The presented calculations show that the substantial increase in the cooling efficiency can be attained due to channels of small dimension in the blade wall.  

An Improved Nickel Based MIMS Thermocouple for High Temperature Gas Turbine Applications

2012 ◽  
Author(s):  
Michele Scervini ◽  
Catherine Rae
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
High Temperatures ◽  
Gas Turbines ◽  
Material Science ◽  
University Of Cambridge ◽  
Type K ◽  
Metallurgical Analysis ◽  
The University ◽  
High Temperature Gas

A new Nickel based thermocouple for high temperature applications in gas turbines has been devised at the Department of Material Science and Metallurgy of the University of Cambridge. This paper describes the new features of the thermocouple, the drift tests on the first prototype and compares the behaviour of the new sensor with conventional mineral insulated metal sheathed Type K thermocouples: the new thermocouple has a significant improvement in terms of drift and temperature capabilities. Metallurgical analysis has been undertaken on selected sections of the thermocouples exposed at high temperatures which rationalises the reduced drift of the new sensor. A second prototype will be tested in follow-on research, from which further improvements in drift and temperature capabilities are expected.

scholarly journals Cooling and Sealing Air System in Industrial Gas Turbine Engines

1996 ◽  
Author(s):  
A. W. Reichert ◽  
M. Janssen
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Gas Turbines ◽  
State Of The Art ◽  
Cooling System ◽  
Inlet Temperature ◽  
Turbine Inlet ◽  
Air System ◽  
Calculation System ◽  
Cooling Air

Siemens heavy duty Gas Turbines have been well known for their high power output combined with high efficiency and reliability for more than 3 decades. Offering state of the art technology at all times, the requirements concerning the cooling and sealing air system have increased with technological development over the years. In particular the increase of the turbine inlet temperature and reduced NOx requirements demand a highly efficient cooling and sealing air system. The new Vx4.3A family of Siemens gas turbines with ISO turbine inlet temperatures of 1190°C in the power range of 70 to 240 MW uses an effective film cooling technique for the turbine stages 1 and 2 to ensure the minimum cooling air requirement possible. In addition, the application of film cooling enables the cooling system to be simplified. For example, in the new gas turbine family no intercooler and no cooling air booster for the first turbine vane are needed. This paper deals with the internal air system of Siemens gas turbines which supplies cooling and sealing air. A general overview is given and some problems and their technical solutions are discussed. Furthermore a state of the art calculation system for the prediction of the thermodynamic states of the cooling and sealing air is introduced. The calculation system is based on the flow calculation package Flowmaster (Flowmaster International Ltd.), which has been modified for the requirements of the internal air system. The comparison of computational results with measurements give a good impression of the high accuracy of the calculation method used.

Leading Edge Shielding Concept in Gas Turbines With Can Combustors

2012 ◽  
Author(s):  
Ioanna Aslanidou ◽  
Budimir Rosic ◽  
Vasudevan Kanjirakkad ◽  
Sumiu Uchida
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Gas Turbines ◽  
Leading Edge ◽  
High Heat ◽  
Gas Temperature ◽  
Cooling Strategies ◽  
Film Cooling Holes ◽  
Cooling Air ◽  
Heat Loads

The remarkable developments in gas turbine materials and cooling technologies have allowed a steady increase in combustor outlet temperature and hence in gas turbine efficiency over the last half century. However, the efficiency benefits of higher gas temperature, even at the current levels, are significantly offset by the increased losses associated with the required cooling. Additionally, the advancements in gas turbine cooling technology have introduced considerable complexities into turbine design and manufacture. Therefore, a reduction in coolant requirements for the current gas temperature levels is one possible way for gas turbine designers to achieve even higher efficiency levels. The leading edges of the first turbine vane row are exposed to high heat loads. The high coolant requirements and geometry constraints limit the possible arrangement of the multiple rows of film cooling holes in the so called showerhead region. In the past, investigators have tested many different showerhead configurations, varying the number of rows, inclination angle and shape of the cooling holes. However the current leading edge cooling strategies using showerheads have not been shown to allow further increase in turbine temperature without excessive use of coolant air. Therefore new cooling strategies for the first vane have to be explored. In gas turbines with multiple combustor chambers around the annulus, the transition duct walls can be used to shield, i.e. to protect the first vane leading edges from the high heat loads. In this way the stagnation region at the leading edge and the shower-head of film cooling holes can be completely removed, resulting in a significant reduction in the total amount of cooling air that is otherwise required. By eliminating the showerhead the shielding concept significantly simplifies the design and lowers the manufacturing costs. This paper numerically analyses the potential of the leading edge shielding concept for cooling air reduction. The vane shape was modified to allow for the implementation of the concept and non-restrictive relative movement between the combustor and the vane. It has been demonstrated that the coolant flow that was originally used for cooling the combustor wall trailing edge and a fraction of the coolant air used for the vane showerhead cooling can be used to effectively cool both the suction and the pressure surfaces of the vane.

Numerical Investigation on Cooling Air Flow and Resistance Characteristics Inner Laminated Cooling Structures

2019 ◽  
Author(s):  
Wei Song ◽  
Huazhao Xu ◽  
Xiaofang Cheng ◽  
Jianhua Wang
Keyword(s):  
Numerical Investigation ◽  
Flow Rate ◽  
Film Cooling ◽  
Gas Turbines ◽  
Flow Resistance ◽  
Resistance Coefficient ◽  
Inlet Velocity ◽  
Cooling Air ◽  
Laminated Structures ◽  
Simple Film

Abstract Today, laminated cooling structures have been widely used in the designs of advanced gas turbines, because the structures with double walls, pins, impingement holes and film holes can provide much higher overall cooling effectiveness than simple film cooling. Of course, this kind of cooling structures also leads to a higher price due to a larger flow resistance to cooling air injection in comparison with the simple film cooling. The previous investigations concerned with the laminated cooling structures mainly focused on heat transfer performances, the flow resistance characteristics within the complex channel of the structures are relatively less. This paper presents a numerical investigation on the characteristics of the cooling air resistance passing through 6 different laminated structures. The influence factors on the fluid flow and resistance performances of cooling air, such as array, density and shape of film hole, as well as impingement-hole area (diameter), are discussed and compared at the same pressure ratios of the inlet to outlet of the 6 laminated structures. The discussions and comparisons reveal the following interesting phenomena: 1) A larger diameter of impingement hole corresponds to a larger mass flow rate of cooling air at the inlet of the laminated structure, but the inlet velocity is mainly dependent on the density of film hole. At the same total area of film holes, a larger density corresponds to a higher inlet velocity. 2) The flow rate through film hole of laminated structures is influenced more and more obvious by the outlet shape and the inflow angle of film hole as the increasing pressure ratio. 3) The resistance coefficients of the entire laminated structures are dependent on the density and shape of film holes. At the same total area of film holes, a higher density corresponds to a lower resistance coefficient. Although fan-shaped film hole can provide a larger cooling air coverage, the price is a higher resistance coefficient. Therefore, the applications of fan-shaped film holes in the laminated structures should be considered only in the regions with low environment pressures.

Highest-Efficient Film Cooling by Improved NEKOMIMI Film Cooling Holes: Part 1 — Ambient Air Flow Conditions

2013 ◽  
Author(s):  
Karsten Kusterer ◽  
Nurettin Tekin ◽  
Frederieke Reiners ◽  
Dieter Bohn ◽  
Takao Sugimoto ◽  
...  
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Air Flow ◽  
Ambient Air ◽  
Flow Conditions ◽  
Test Rig ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Technology ◽  
Cooling Air

In modern gas turbines, the film cooling technology is essential for the protection of the hot parts, in particular of the first stage vanes and blades of the turbine, against the hot gases from the combustion process in order to reach an acceptable life span of the components. As the cooling air is usually extracted from the compressor, the reduction of the cooling effort would directly result to an increased thermal efficiency of the gas turbine. Understanding of the fundamental physics of film cooling is necessary for the improvement of the state-of-the-art. Thus, huge research efforts by industry as well as research organizations have been undertaken to establish high efficient film cooling technologies. It is a today common knowledge that film cooling effectiveness degradation is caused by secondary flows inside the cooling jets, i.e. the Counter-Rotating Vortices (CRV) or sometimes also mentioned as kidney-vortices, which induce a lift-off of the jet. Further understanding of the secondary flow development inside the jet and how this could be influenced, has led to hole configurations, which can induce Anti-Counter-Rotating Vortices (ACRV) in the cooling jets. As a result, the cooling air remains close to the wall and is additionally distributed flatly along the surface. Beside different other technologies, the NEKOMIMI cooling technology is a promising approach to establish the desired ACRV. It consists of a combination of two holes in just one configuration so that the air is distributed mainly on two cooling air streaks following the special shape of the generated geometry. The original configuration was found to be difficult for manufacturing even by advanced manufacturing processes. Thus, the improvement of this configuration has been reached by a set of geometry parameters, which lead to configurations much easier to be manufactured but preserving the principle of the NEKOMIMI technology. Within a numerical parametric study several advanced configurations have been obtained and investigated under ambient air flow conditions similar to conditions for a wind tunnel test rig. By systematic variation of the parameters a further optimization with respect to highest film cooling effectiveness has been performed. A set of most promising configurations has been also investigated experimentally in the test rig. The best configuration outperforms the basic configuration by 17% regarding the overall averaged adiabatic film cooling effectiveness under the experimental conditions.

A Catalytic Combustor for High-Temperature Gas Turbines

1996 ◽  
Vol 118 (1) ◽  
pp. 61-64 ◽  
Author(s):  
N. Vortmeyer ◽  
M. Valk ◽  
G. Kappler
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Essential Feature ◽  
Research Work ◽  
Thermal Reactor ◽  
Experimental Investigations ◽  
Phase Reaction ◽  
Catalyst Temperature ◽  
Catalytic Combustor ◽  
High Temperature Gas

Catalytic combustion has been the subject of thorough research work for over two decades, mainly in the U.S. and Japan. However, severe material problems in the ceramic or metallic monolith prevented regular operation in most cases. Still, during these two decades, turbine inlet temperatures were raised remarkably, and lean premix combustors have become standard in stationary gas turbines. In view of these facts, a simple “monolith-in-tube” concept of a catalytic combustor was adapted for the use in high-temperature gas turbines. Its essential feature is the fact that a considerable portion of the homogeneous gas phase reaction is shifted to the thermal reactor, thus lowering the catalyst temperature. This is achieved by the employment of very short catalyst segments. The viability of this concept has been demonstrated for a variety of pure hydrocarbons, alcohols as well as common liquid fuels. Extensive experimental investigations of the atmospheric combustor led to the assessment of parameters such as reference velocity, fuel-to-air ratio, and fuel properties. The maximum combustor exit temperature was 1673 K with a corresponding catalyst temperature of less than 1300 K for diesel fuel. Boundary conditions were in all cases combustion efficiency (over 99.9 percent) and pressure loss (less than 6 percent). Additionally, a model has been developed to predict the characteristic values of the catalytic combustor such as necessary catalyst length, combustor volume, and emission characteristics. The homogeneous reaction in the thermal reactor can be calculated by a one-dimensional reacting flow model.

scholarly journals Gas Turbine Power Plant Possibilities With a Nuclear Heat Source: Closed and Open Cycles

1990 ◽  
Author(s):  
Colin F. McDonald
Keyword(s):  
High Temperature ◽  
Power Plant ◽  
Heat Source ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Combined Cycle ◽  
Closed Cycle ◽  
Cycle System ◽  
Nuclear Heat ◽  
High Temperature Gas

With the capability of burning a variety of fossil fuels, giving high thermal efficiency, and operating with low emissions, the gas turbine is becoming a major prime-mover for a wide spectrum of applications. Almost three decades ago two experimental projects were undertaken in which gas turbines were actually operated with heat from nuclear reactors. In retrospect, these systems were ahead of their time in terms of technology readiness, and prospects of the practical coupling of a gas turbine with a nuclear heat source towards the realization of a high efficiency, pollutant free, dry-cooled power plant has remained a long-term goal, which has been periodically studied in the last twenty years. Technology advancements in both high temperature gas-cooled reactors, and gas turbines now make the concept of a nuclear gas turbine plant realizable. Two possible plant concepts are highlighted in this paper, (1) a direct cycle system involving the integration of a closed-cycle helium gas turbine with a modular high temperature gas cooled reactor (MHTGR), and (2) the utilization of a conventional and proven combined cycle gas turbine, again with the MHTGR, but now involving the use of secondary (helium) and tertiary (air) loops. The open cycle system is more equipment intensive and places demanding requirements on the very high temperature heat exchangers, but has the merit of being able to utilize a conventional combined cycle turbo-generator set. In this paper both power plant concepts are put into perspective in terms of categorizing the most suitable applications, highlighting their major features and characteristics, and identifying the technology requirements. The author would like to dedicate this paper to the late Professor Karl Bammert who actively supported deployment of the closed-cycle gas turbine for several decades with a variety of heat sources including fossil, solar, and nuclear systems.

scholarly journals A Catalytic Combustor for High-Temperature Gas Turbines

1994 ◽  
Author(s):  
Nicolas Vortmeyer ◽  
Martin Valk ◽  
Günter Kappler
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Essential Feature ◽  
Research Work ◽  
Thermal Reactor ◽  
Experimental Investigations ◽  
Phase Reaction ◽  
Catalyst Temperature ◽  
Catalytic Combustor ◽  
High Temperature Gas

Catalytic combustion has been the subject of thorough research work for over two decades, mainly in the U.S. and Japan. However, severe material problems in the ceramic or metallic monolith prevented regular operation in most cases. Still, during these two decades, turbine inlet temperatures were raised remarkably, and lean premix combustors have become standard in stationary gas turbines. In view of these facts, a simple “monolith-in-tube” concept of a catalytic combustor was adapted for the use in high-temperature gas turbines. Its essential feature is the fact that a considerable portion of the homogeneous gas phase reaction is shifted to the thermal reactor, thus lowering the catalyst temperature. This is achieved by the employment of very short catalyst segments. The viability of this concept has been demonstrated for a variety of pure hydrocarbons, alcohols as well as common liquid fuels. Extensive experimental investigations of the atmospheric combustor lead to the assessment of parameters such as reference velocity, fuel-to-air ratio and fuel properties. The maximum combustor exit temperature was 1,673 K with a corresponding catalyst temperature of less than 1,300 K for Diesel fuel. Boundary conditions were in all cases combustion efficiency (over 99.9%) and pressure loss (less than 6%). Additionally, a model has been developped to predict the characteristic values of the catalytic combustor such as necessary catalyst length, combustor volume and emission characteristics. The homogeneous reaction in the thermal reactor can be calculated by a one-dimensional reacting flow model.

Sign in / Sign up

Export Citation Format

Share Document