Experimental and Numerical Analysis of the Flow Structure and Dust Separation Inside a Pre-Swirl Cooling Air System

2003 ◽  
Author(s):  
O. Schneider ◽  
H. J. Dohmen ◽  
F.-K. Benra ◽  
D. Brillert
Keyword(s):  
Numerical Analysis ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Internal Cooling ◽  
Flow Conditions ◽  
Test Rig ◽  
Complex Flow ◽  
Air System ◽  
Cooling Air

Improvements in efficiency and performance of gas turbines require a better understanding of the internal cooling air system which provides the turbine blades with cooling air. With the increase of cooling air passing through the internal air system, a greater amount of air borne particles is transported to the film cooling holes at the turbine blade surface. In spite of their small size, these holes are critical for blockage. Blockage of only a few holes could have harmful effects on the cooling film surrounding the blade. As a result, a reduced mean time between maintenance or even unexpected operation faults of the gas turbine during operation could occur. Experience showed a complex interaction of cooling air under different flow conditions and its particle load. To get more familiar with all these influences and the system itself, a test rig has been built. With this test rig, the behavior of particles in the internal cooling air system can be studied at realistic flow conditions compared to a modern, heavy duty gas turbine. It is possible to simulate different particle sizes and dust concentrations in the coolant air. The test rig has been designed to give information about the quantity of separated particles at various critical areas of the internal air system [1]. The operation of the test rig as well as analysis of particles in such a complex flow system bear many problems, addressed in previous papers [1,2,3]. New theoretical studies give new and more accurate results, compared to the measurements. Furthermore the inspection of the test rig showed dust deposits at unexpected positions of the flow path, which will be discussed by numerical analysis.

Investigations of Dust Separation in the Internal Cooling Air System of Gas Turbines

2003 ◽  
Author(s):  
O. Schneider ◽  
H. J. Dohmen ◽  
F.-K. Benra ◽  
D. Brillert
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Internal Cooling ◽  
Flow Conditions ◽  
Test Rig ◽  
Complex Flow ◽  
Air System ◽  
Cooling Air

Improvements in efficiency and performance of gas turbines require a better understanding of the internal cooling air system which provides the turbine blades with cooling air. With the increase of cooling air passing through the internal air system, a greater amount of air borne particles is transported to the film cooling holes at the turbine blade surface. In spite of their small size, these holes are critical for blockage. Blockage of only a few holes could have harmful effects on the cooling film surrounding the blade. As a result, a reduced mean time between maintenance or even unexpected operation faults of the gas turbine during operation could occure. Experience showed a complex interaction of cooling air under different flow conditions and its particle load. To get more familiar with all these influences and the system itself, a test rig has been built. With this test rig, the behaviour of particles in the internal cooling air system could be studied at realistic flow conditions compared to a modern, heavy duty gas turbine. It is possible to simulate different particle sizes and dust concentrations in the coolant air. The test rig has been designed to give information about the quantity of separated particles at various critical areas of the internal air system [1]. The operation of the test rig as well as analysis of particles in such a complex flow system bear many problems, addressed in the previous paper [1]. New measurements and analysis methods give new and more accurate results, which will be shown in this paper. Furthermore the inspection of the test rig shows dust deposits at unexpected positions of the flow path. Theoretical studies to characterize the flow behaviour of the disperse phase in a continuous fluid using Lagrangian Tracking were also performed. A comparison between the numerical solution and the measurements will be shown in the paper.

Experimental Analysis of Dust Separation in the Internal Cooling Air System of Gas Turbines

2002 ◽  
Author(s):  
O. Schneider ◽  
H. J. Dohmen ◽  
A. W. Reichert
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Gas Turbines ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Internal Cooling ◽  
Test Rig ◽  
Air System ◽  
And Performance ◽  
Cooling Air

For further improvements in efficiency and performance a better understanding of the internal cooling air system of gas turbines, which provides the turbine rotor blades with cooling air, is necessary. With the increase of cooling air passing through the internal air system, a greater amount of air borne particles are transported to the film cooling holes at the turbine blade surface. In spite of their small size, these holes are critical for blade cooling. Blockage of only a few holes could have harmful effects on the cooling film surrounding the blade. As a result, a reduced mean time between maintenance or even unexpected operation faults of the gas turbine during operation occurs. With a new test rig, the behaviour of particles in the internal cooling air system could be investigated at realistic flow conditions compared to a modern, real world gas turbine. It is possible to simulate different particle sizes and dust concentrations in the coolant air. A first comparison of design expectations and measurements, showing the behaviour of air borne particles in the internal cooling air system under realistic environmental conditions is given in the paper. Further the design tools for nearly a full internal air system flow path could be validated with this new test rig.

Dust Separation in a Gas Turbine Pre-Swirl Cooling Air System: A Parameter Variation

2004 ◽  
Author(s):  
O. Schneider ◽  
H. J. Dohmen ◽  
F.-K. Benra ◽  
D. Brillert
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Gas Turbines ◽  
Flow Behavior ◽  
Internal Cooling ◽  
Test Rig ◽  
Swirl Generator ◽  
Air System ◽  
Heavy Duty Gas Turbine ◽  
Cooling Air

With the increase of cooling air passing through the internal air system of modern gas turbines, a greater amount of air borne particles is transported to the film cooling holes at the turbine blade surface. In spite of their small size, these holes are critical for blockage. A test rig has been designed to give information about the quantity of separated particles at various critical areas of the internal air system. With this test rig, the behavior of particles in the internal cooling air system could be studied at realistic flow conditions compared to a modern, heavy duty gas turbine. It is possible to simulate different particle sizes and dust concentrations in the coolant air. Numerical studies to characterize the flow behavior of the disperse phase in a continuous fluid using Lagrange Tracking were performed. The main influencing parameters, which are the mass flow through the system, the rotor speed and the nozzle angle of the pre-swirl generator, were varied. Furthermore to validate the theoretical studies, based on the presented variations a special point of operation was selected to get a comparable measurement, which is presented in the paper. Comparison between simulation and measurement shows additional influences of the particle shape, which were discussed. The resulting enhanced model and the comparison to the measurement is presented in the paper.

A Contribution to the Abrasive Effect of Particles in a Gas Turbine Pre-Swirl Cooling Air System

2005 ◽  
Author(s):  
O. Schneider ◽  
F.-K. Benra ◽  
H. J. Dohmen ◽  
K. Jarzombek
Keyword(s):  
Gas Turbine ◽  
Flow Structure ◽  
Film Cooling ◽  
Gas Turbines ◽  
Test Rig ◽  
Critical Areas ◽  
Air System ◽  
Quantitative Results ◽  
Film Cooling Holes ◽  
Cooling Air

With the increase of cooling air passing through the internal air system of modern gas turbines, a greater number of airborne particles is transported to the film cooling holes in the turbine blade surface. In spite of their small size, these holes are critical for airflow and must be free of blockage. A test rig has been designed to study the quantity of separated particles at various critical areas of the internal air system. Former publications for this conference gave detailed insight into the test rig, the flow structure and the particle motion during separation. The process of separation generates abrasion on the rotating and stationary parts of the system. When considering service and maintenance or even unexpected operation faults of the gas turbine, it is important to know the location and abrasion rate of these critical areas. The flow structure within the pre-swirl cooling air system results in locally focused abrasion regions, which are investigated in this paper. New simulations, taking additional physical effects into account, are discussed in the paper. The simulation results are compared to results obtained by measurements and observations within the test rig. Qualitative and quantitative results show the ability to predict the quantity of abrasion during operation on various critical areas of the system.

Investigation of Internal Cooling Air Flow of Gas Turbines With Attention to Heat Transfer

2003 ◽  
Author(s):  
D. Brillert ◽  
F.-K. Benra ◽  
H. J. Dohmen ◽  
O. Schneider
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Internal Cooling ◽  
Flow Physics ◽  
Cooling Flow ◽  
Air System ◽  
Secondary Air ◽  
Cooling Air ◽  
Material Temperature

The cooling air in the secondary air system of gas turbines is routed through the inside of the rotor shaft. The air enters the rotor through an internal extraction in the compressor section and flows through different components to the turbine blades. Constant improvements of the secondary air system is a basic element to increase efficiency and power of heavy duty gas turbines. It is becoming more and more important to have a precise calculation of the heat transfer and air temperature in the internal cooling air system. This influences the cooling behavior, the material temperature and consequently the cooling efficiency. The material temperature influences the stresses and the creep behavior which is important for the life time prediction and the reliability of the components of the engine. Furthermore, the material temperature influences the clearances and again the cooling flow, e.g. the amount of mass flow rate, hot gas ingestion etc. This paper deals with an investigation of the influence of heat transfer on the internal cooling air system and on the material temperature. It shows a comparison between numerical calculations with and without heat transfer. Firstly, the Navier-Stokes CFD calculation shows the cooling flow physics of different parts of the secondary air system passages with solid heat transfer. In the second approach, the study is expanded to consider the cooling flow physics under conditions without heat transfer. On the basis of these investigations, the paper shows a comparison between the flow with and without heat transfer. The results of the simulation with heat transfer show a negligible influence on the cooling flow temperature and a stronger influence on the material temperature. The results of the calculations are compared with measured data. The influence on the material temperature is verified with measured material temperatures from a Siemens Model V84.3A gas turbine prototype.

A New Test Rig for Time-Resolved Pressure Measurements in Rotating Cavities With Pulsed Inflow

2010 ◽  
Author(s):  
Gunar Schroeder ◽  
Wieland Uffrecht
Keyword(s):  
Gas Turbines ◽  
Pressure Fluctuations ◽  
Rotational Frequency ◽  
Internal Cooling ◽  
Pressure Measurements ◽  
Test Rig ◽  
Time Resolved ◽  
Air System ◽  
Unsteady Effects ◽  
Cooling Air

The improvement of the overall performance and efficiency of gas turbines, especially in the internal cooling air system is of general interest. This requires the reduction of pressure losses induced by vortices and secondary flow. The steady state effects are known from literature and experiments. But also pressure fluctuations and oscillations e.g. resonances have an impact on the efficiency of the internal cooling air system. These unsteady effects are only principally discussed in the literature. Experimental investigations of pressure fluctuations and oscillations in rotating cavities, which are part of the internal air system, are very rare. One reason might be given by the fact that the investigation of these unsteady effects is a technical challenge especially for higher rotational speeds. This paper presents a new rotor test rig with a telemetric measurement system which permits time-resolved pressure measurements in the cavity. The cavity dimensions are similar to those of a real industrial gas turbine. The design of the test rig and the telemetric system allows rotational frequencies up to 10000 rpm. The current experimental investigation is focused on pressure fluctuations and oscillations in rotating cavities with through flow and their dependency on the test parameters. The aim is to find out the relevant effects for operation and design optimisation of rotating cavities in gas turbines. The rig consists of a stationary air delivery and an axial air transfer interface between the stator and the rotor. The rotor contains one cavity. The interface acts as a flow chopper. The air is blown from the stator drillings to the rotating inlet holes of the rotor which provide the connection to the cavity inside the rotor. The rotating holes pass the stator holes periodically, causing pressure fluctuations in the cavity. The frequency of the fluctuations depends on the rotational frequency of the rotor and the number of inlet and stator drillings, which can be varied. The tests are carried out for a range of the parameter Reφ, calculated with the outer radius of the cavity, up to 1·106 and for different mass flow rates. The new test rig, the setup, the instrumentation and the first measurements are the topic of this paper. The non-stationary effects found in the cavity and their dependency on the parameters rotational frequency and mass flow will be discussed and compared with known theoretical approaches.

Pulsed Impingement Turbine Cooling and its Effect on the Efficiency of Gas Turbines With Pressure Gain Combustion

2020 ◽  
Author(s):  
Nicolai Neumann ◽  
Dieter Peitsch ◽  
Arne Berthold ◽  
Frank Haucke ◽  
Panagiotis Stathopoulos
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Impingement Cooling ◽  
Turbine Cooling ◽  
Pressure Gain Combustion ◽  
Cooling Air ◽  
Gas Turbine Cycle ◽  
Cycle Efficiency

Abstract Performance improvements of conventional gas turbines are becoming increasingly difficult and costly to achieve. Pressure Gain Combustion (PGC) has emerged as a promising technology in this respect, due to the higher thermal efficiency of the respective ideal gas turbine cycle. Previous cycle analyses considering turbine cooling methods have shown that the application of pressure gain combustion may require more turbine cooling air. This has a direct impact on the cycle efficiency and reduces the possible efficiency gain that can potentially be harvested from the new combustion technology. Novel cooling techniques could unlock an existing potential for a further increase in efficiency. Such a novel turbine cooling approach is the application of pulsed impingement jets inside the turbine blades. In the first part of this paper, results of pulsed impingement cooling experiments on a curved plate are presented. The potential of this novel cooling approach to increase the convective heat transfer in the inner side of turbine blades is quantified. The second part of this paper presents a gas turbine cycle analysis where the improved cooling approach is incorporated in the cooling air calculation. The effect of pulsed impingement cooling on the overall cycle efficiency is shown for both Joule and PGC cycles. In contrast to the authors’ anticipation, the results suggest that for relevant thermodynamic cycles pulsed impingement cooling increases the thermal efficiency of Joule cycles more significantly than it does in the case of PGC cycles. Thermal efficiency improvements of 1.0 p.p. for pure convective cooling and 0.5 p.p. for combined convective and film with TBC are observed for Joule cycles. But just up to 0.5 p.p. for pure convective cooling and 0.3 p.p. for combined convective and film cooling with TBC are recorded for PGC cycles.

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.

Managing Fuel Oil Nozzle Coking to Improve Gas Turbine Availability

2000 ◽  
Author(s):  
Leo R. Burgett ◽  
Tim Mercer
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Fuel Oil ◽  
Power Company ◽  
Ac Motor ◽  
Air System ◽  
Oil Residue ◽  
Cooling Air ◽  
Fuel Burner

Fuel oil nozzle coking has been a continuing problem for operators of gas turbine power plants. Over the years, several “solutions” to eliminate the coking of the fuel oil have been implemented to improve plant reliability and availability. When the fuel oil nozzle is “coked”, the startup and operation of the gas turbine are impaired and an unscheduled outage is needed to clean the fuel oil nozzle. In 1997, a project was initiated to investigate the coking problem as it affects the operation of the dual fuel burner of the ABB ALSTOM POWER Inc. GT11N1 single burner (SBK) gas turbine. The GT11N1 SBK fuel oil nozzle (see FIGURE 1) was failing to operate properly because of “coked” fuel oil residue on its internal components (stationary and moveable). ABB ALSTOM POWER Inc. teamed with Savannah Electric & Power Company and collected data that indicated adequate nozzle cooling air could reduce the rate of fuel oil coking. A nozzle cooling air system modification was installed on one of the ABB ALSTOM POWER Inc. 11N1 gas turbines at the Savannah Electric & Power Company McIntosh Power Plant. The modification included an AC motor driven air blower to provide cooling air to the fuel oil nozzle after shutdown of the gas turbine. Inspection of the components inside the fuel oil nozzle showed that very little fuel oil oxidation had occurred inside the nozzle during the three-month test period. By improving the fuel oil nozzle cooling air system, the coking problem can be better managed.

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.

Sign in / Sign up

Export Citation Format

Share Document