Strut Influences Within a Diffusing Annular S-Shaped Duct

1998 ◽  
Author(s):  
G. Norris ◽  
R. G. Dominy ◽  
A. D. Smith
Keyword(s):  
Gas Turbines ◽  
Total Pressure ◽  
Pressure Measurements ◽  
Computational Results ◽  
Flow Conditions ◽  
Test Rig ◽  
General Flow ◽  
Flow Phenomena ◽  
Physical Features ◽  
Cooling Air

Inter-turbine diffusers which provide flow continuity between the H.P. and L.P. turbines, are increasingly important within modern aero gas turbines, as the fan and hence L.P. turbine diameters increase with thrust. These gas turbines rely on struts within the inter-turbine diffuser to serve both as load bearing supports for inner spools and as passages to supply the engine with vital services such as cooling air and lubrication oil. Experimental measurements have been made on a representative test rig in order to investigate the affect of a ring of struts on both the local and general flow phenomena as well as investigating their effect on overall duct performance. More realistic flow conditions are made available by the use of inlet wakes representative of those created by an upstream turbine row. Measurements include static pressures on the strut and duct surfaces along with velocity and total pressure measurements at various axial locations. From these results calculations of total pressure loss have been made. The experimental results presented in this paper have been used to validate C.F.D. flow predictions on the duct with and without struts. The computational results included, capture the main physical features of the flow but clear limitations are observed and are discussed in this paper.

The Effect of Vanes and Blades on Ingress in Gas Turbines

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
Fabian P. Hualca ◽  
Joshua T. M. Horwood ◽  
Carl M. Sangan ◽  
Gary D. Lock ◽  
James A. Scobie
Keyword(s):  
Gas Turbines ◽  
Large Scale ◽  
Strong Influence ◽  
Rotor Blades ◽  
Pressure Measurements ◽  
Computational Results ◽  
Test Rig ◽  
Rotor Disk ◽  
Unsteady Pressure Measurements ◽  
The Relationship

Abstract This paper presents experimental and computational results using a 1.5-stage test rig designed to investigate the effects of ingress through a double radial overlap rim-seal. The effect of the vanes and blades on ingress was investigated by a series of carefully controlled experiments: first, the position of the vane relative to the rim seal was varied; second, the effect of the rotor blades was isolated using a disk with and without blades. Measurements of steady pressure in the annulus show a strong influence of the vane position. The relationship between sealing effectiveness and purge flowrate exhibited a pronounced inflection for intermediate levels of purge; the inflection did not occur for experiments with a bladeless rotor. Shifting the vane closer to the rim-seal, and therefore the blade, caused a local increase in ingress in the inflection region; again, this effect was not observed for the bladeless experiments. Unsteady pressure measurements at the periphery of the wheel-space revealed the existence of large-scale pressure structures (or instabilities) which depended weakly on the vane position and sealing flowrate. These were measured with and without the blades on the rotor disk. In all cases, these structures rotated close to the disk speed.

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.

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.

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.

Total Pressure Losses in Rotor Systems With Radial Inflow

2000 ◽  
Author(s):  
D. Brillert ◽  
D. Lieser ◽  
A. W. Reichert ◽  
H. Simon
Keyword(s):  
Gas Turbines ◽  
Total Pressure ◽  
Simple Calculation ◽  
Calculation Model ◽  
Navier Stokes ◽  
Test Bed ◽  
Rotor Systems ◽  
Pressure Losses ◽  
Flow Phenomena ◽  
Cooling Air

Gas turbines with a splined-disc rotor design allow the compressor bleed pressure to be adapted precisely to the requirements of rotor cooling air systems in which the cooling air is routed through the spaced between the rotating discs. Calculation of such flows is extremely difficult; particularly so if the flow is directed radially inward. In such cases the circumferential component of the absolute velocity can be very high and can thus lead to pronounced total pressure losses. The paper gives a brief description of the flow phenomena, and details in the calculation methods cited in the literature. Navier–Stokes calculations were carried out for the flow through a model test bed engine. The results are compared with experimental data. A simple calculation model is discussed and its result compared with test data. The model predicts the flow pattern more accurately than the Navier-Stokes calculations, and this paper shows that the simple model can be improved further.

Time-Resolved Pressure Measurements at a Dual-Cavity Test Rig for Research on the Internal Air System of an Industrial Gas Turbine

2014 ◽  
Author(s):  
André Günther ◽  
Wieland Uffrecht ◽  
Volker Caspary
Keyword(s):  
Gas Turbines ◽  
Pressure Fluctuations ◽  
Pressure Measurements ◽  
Test Rig ◽  
Time Resolved ◽  
Hot Gas ◽  
Air Supply ◽  
Internal Cavities ◽  
Air System ◽  
Cooling Air

This paper reports about time-resolved examination of the pressure in a dual-cavity test rig for research on the cooling air supply of industrial gas turbines. The test rig has stationary and telemetric instrumentation. Both systems are capable of time-resolved pressure measurement. The design of the test rig is based on a simplified geometry of the internal cavities of the high pressure turbine with receiver holes and simulates the restriction imposed by internal blade cooling flow circuits. The test rig consists of a rotor-stator cavity and a rotor-rotor cavity. The Stage One and Stage Two supplies are separated inside the rotor-stator cavity. The air enters axially without pre-swirl at the outer radius of the stator and leaves the rotor-stator cavity through three rotating, axially directed connecting holes at a radius that varies among the investigated cases. Therefore, different flow paths in the cavities are studied. The research is focused on the branched cooling air supply system, but the flow path can also be analyzed separately. The rim seal flow is not examined in the research work presented here. Pressure fluctuations in the main gas path caused, for instance, by blade passing and combustor noise, are a well-known phenomenon and therefore the subject of current research, whereas experimental examinations of the pressure fluctuations in the internal air system of gas turbines are very rare. A detailed examination of the pressure in the internal air system is significant in light of the pressure difference between the main gas path and internal air system, which is the driving force for hot gas ingestion. In that sense, the difference between the average pressure on the main gas side to the average pressure in the internal air system is not enough to avoid hot gas ingestion. Therefore, this paper focuses on pressure fluctuations in the internal cavities. The measurements of the pressure fluctuations in the rotor-stator cavity are presented for different operating conditions. The influence of the rotational speed, the mass flow rate, the flow path and the sensor position in the cavity on the time-resolved pressure is examined. Furthermore, time-resolved pressure measurements from the rotor-rotor cavity are presented. Variations of the axial gap size and the radial location of the connecting holes respective to the outlets of the rotor-stator cavity are described.

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.

scholarly journals Numerical and Experimental Investigations on Optimized 3D Compressor Airfoils

2018 ◽  
Author(s):  
Jan Mihalyovics ◽  
Christian Brück ◽  
Dieter Peitsch ◽  
Ilias Vasilopoulos ◽  
Marcus Meyer
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Experimental Studies ◽  
Total Pressure Loss ◽  
Design Parameters ◽  
Flow Conditions ◽  
Flow Angle ◽  
Flow Phenomena ◽  
The Impact ◽  
Stator Design

The objective of the presented work is to perform numerical and experimental studies on compressor stators. This paper presents the modification of a baseline stator design using numerical optimization resulting in a new 3D stator. The Rolls Royce in-house compressible flow solver HYDRA was employed to predict the 3D flow, solving the steady RANS equations with the Spalart-Allmaras turbulence model, and its corresponding discrete adjoint solver. The performance gradients with respect to the input design parameters were used to optimize the stator blade with respect to the total pressure loss over a prescribed incidence range, while additionally minimizing the flow deviation from the axial direction at the stator exit. Non-uniform profile boundary conditions, being derived from the experimental measurements, have been defined at the inlet of the CFD domain. The presented results show a remarkable decrease in the axial exit flow angle deviation and a minor decrease in the total pressure loss. Experiments were conducted on two compressor blade sets investigating the three-dimensional flow in an annular compressor stator cascade. Comparing the baseline flow of the 42° turning stator shows that the optimized stator design minimizes the secondary flow phenomena. The experimental investigation discusses the impact of steady flow conditions on each stator design while focusing on the comparison of the 3D optimized design to the baseline case. The flow conditions were investigated using five-hole probe pressure measurements in the wake of the blades. Furthermore, oil-flow visualization was applied to characterize flow phenomena. These experimental results are compared with the CFD calculations.

scholarly journals Impact of a Cooled Cooling Air System on the External Aerodynamics of a Gas Turbine Combustion System

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
A. Duncan Walker ◽  
Bharat Koli ◽  
Liang Guo ◽  
Peter Beecroft ◽  
Marco Zedda
Keyword(s):  
Gas Turbines ◽  
Pressure Loss ◽  
Total Pressure ◽  
Outer Wall ◽  
Total Pressure Loss ◽  
Test Facility ◽  
Combustion System ◽  
Air System ◽  
External Aerodynamics ◽  
Cooling Air

To manage the increasing turbine temperatures of future gas turbines a cooled cooling air system has been proposed. In such a system some of the compressor efflux is diverted for additional cooling in a heat exchanger (HX) located in the bypass duct. The cooled air must then be returned, across the main gas path, to the engine core for use in component cooling. One option is do this within the combustor module and two methods are examined in the current paper; via simple transfer pipes within the dump region or via radial struts in the prediffuser. This paper presents an experimental investigation to examine the aerodynamic impact these have on the combustion system external aerodynamics. This included the use of a fully annular, isothermal test facility incorporating a bespoke 1.5 stage axial compressor, engine representative outlet guide vanes (OGVs), prediffuser, and combustor geometry. Area traverses of a miniature five-hole probe were conducted at various locations within the combustion system providing information on both flow uniformity and total pressure loss. The results show that, compared to a datum configuration, the addition of transfer pipes had minimal aerodynamic impact in terms of flow structure, distribution, and total pressure loss. However, the inclusion of prediffuser struts had a notable impact increasing the prediffuser loss by a third and consequently the overall system loss by an unacceptable 40%. Inclusion of a hybrid prediffuser with the cooled cooling air (CCA) bleed located on the prediffuser outer wall enabled an increase of the prediffuser area ratio with the result that the system loss could be returned to that of the datum level.

Unsteady 3D-Numerical Investigation of the Influence of the Blading Design on the Stator-Rotor Interaction in a 2-Stage Turbine

2005 ◽  
Author(s):  
Dieter E. Bohn ◽  
Jing Ren ◽  
Christian Tu¨mmers ◽  
Michael Sell
Keyword(s):  
Gas Turbines ◽  
Flow Characteristics ◽  
Computer Code ◽  
Experimental Investigations ◽  
Blade Design ◽  
Test Rig ◽  
3D Flow ◽  
Two Stage ◽  
Flow Phenomena ◽  
Flow Through

An important goal in the development of turbine bladings is improving their efficiency to achieve an optimized usage of energy resources. This requires a detailed insight into the complex 3D-flow phenomena in multi-stage turbines. In order to investigate the flow characteristics of modern highly loaded turbine profiles, a test rig with a two-stage axial turbine has been set up at the Institute of Steam and Gas Turbines, Aachen University. The test rig is especially designed to investigate different blading designs. In order to analyze the influence of the blade design on the unsteady blade row interaction, the 3D flow through the two-stage turbine is simulated numerically, using an unsteady Navier-Stokes computer code. The investigations include a comparison of two bladings with different design criteria. The reference blading is a commonly used cylindrical designed blading. This blade design will be compared with a bow-blading, which is designed to minimize the secondary flow phenomena near the endwall in order to achieve a balanced mass flow through nearly the whole passage height. The investigations will focus on the different loss behavior of the two bladings. Unsteady profile pressure distributions and radial efficiencies of the two blade designs will be discussed in detail. The flow conditions are taken from experimental investigations performed at the Institute of Steam and Gas Turbines. On the basis of the experiments a validation of the code will be performed by comparing the numerical results to the corresponding experimental data at the inlet and the outlet of the blading.

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