bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design Study of Part Flow Evaporative Gas Turbine Cycles: Performance and Equipment Sizing: Part 2 — Industrial Core
Authors: Ågren Niklas D. , Westermark Mats O. J. 
Published: July 2014

This is part two of a 2-part paper and presents calculation results of a part flow EvGT cycle based on gas turbine data for the ABB GTX100 (modified for intercooling). The evaporative gas turbine cycle is a new high efficiency cycle that has reached the pilot testing stage. This paper presents calculation results of a new humidification strategy based on part flow humidification. This strategy involves using only a fraction of the compressed air for humidification. Thermodynamically, it can be shown that not all the air needs to be passed through the humidification system to attain the intrinsic good flue gas heat recovery of an EvGT cycle. The presented system also includes live steam production and superheating, by heat from the hottest flue gas region, for injection. The humidifier then only uses the lower temperature levels, where it is best suited. The analyzed system is based on data for the ABB GTX100.gas turbine in intercooled mode. Part 1 of this 2-part paper presents the results based on data for the aeroderovative Rolls Royce Trent.
Simulation results include electric efficiency and other process data as function of degree of part flow. A detailed model of the humidifier is used, which produces sizing results both for column height and diameter. Paper 1 includes detailed description of the modelling.
For the GTX100-system, full flow humidification generates an electric efficiency of 52.6% (simple cycle 36.2%). The efficiency is virtually unaffected if the air portion to humidification is cut to 60% of accessible compressor air (represents 48% of compressor intake). If 30% of air from the compressor after cooling bleed (24% of intake)is led to the humidifier, the efficiency is reduced to 52.2%. On the other hand is the total heat exchanger area reduced by 20% and column volume by 50%. This calls for a recommendation not to use all the compressed air for humidification. It is recommended to use 15-30% of compressor intake air. The exact economic optimum depends on local fuel prices, CO2-taxes, interest rates et c.
Film-Cooled Turbine Endwall in a Transonic Flow Field: Part I — Aerodynamic Measurements
Authors: Kost Friedrich , Nicklas Martin 
Published: July 2014

Thermodynamic and aerodynamic measurements were carried out in a linear turbine cascade with transonic flow field. Heat transfer and adiabatic film-cooling effectiveness resulting from the interaction of the flow field and the ejected coolant at the endwall were measured and will be discussed in two parts. The investigations were performed in the Windtunnel for Straight Cascades (EGG) at DLR, Göttingen. The film-cooled NGV endwall was operated at representative dimensionless engine conditions of Mach and Reynolds number Ma2is=1.0 and Re2=850,000 respectively.
Part I of the investigation discusses the aerodynamic measurements. Detailed aerodynamic measurements were carried out in the vicinity of a turbine stator endwall using conventional pressure measurements and a Laser-2-Focus (L2F) device. The L2F served as a velocimeter measuring 2D-velocity vectors and turbulence quantities and as a tool to determine the concentration of coolant ejected through a slot and through holes at the endwall. Pressure distribution measurements provided information on the endwall pressure field and its variation with coolant flow rate. Pressure probe measurements delivered cascade performance data. Oil flow visualization and laser velocimetry gave a picture of the near endwall flow field and its interference with the coolant. A strikingly strong interaction of coolant air and secondary flow field could be identified. The measurement of coolant concentration downstream of the ejection locations provided a detailed picture of the coolant flow convection and its mixing with the main flow. The relative coolant concentration in the flow field is directly comparable to the adiabatic film-cooling effectiveness measured by thermal methods at the wall.
Measurements in a Turbine Cascade Flow Under Ultra Low Reynolds Number Conditions
Authors: Van Treuren Kenneth W. , Simon Terrence , von Koller Marc , Byerley Aaron R. , Baughn James W. , Rivir Richard 
Published: July 2014

With the new generation of gas turbine engines, low Reynolds number flows have become increasingly important. Designers must properly account for transition from laminar to turbulent flow and separation of the flow from the suction surface, which is strongly dependent upon transition. Of interest to industry are Reynolds numbers based upon suction surface length and flow exit velocity below 150,000 and as low as 25,000. In this paper, the extreme low end of this Reynolds number range is documented by way of pressure distributions, loss coefficients and identification of separation zones. Reynolds numbers of 25,000 and 50,000 and with 1% and 8–9% turbulence intensity of the approach flow (Free Stream Turbulence Intensity, FSTI) were investigated.
At 25,000 Reynolds number and low FSTI, the suction surface displayed a strong and steady separation region. Raising the turbulence intensity resulted in a very unsteady separation region of nearly the same size on the suction surface. Vortex generators were added to the suction surface, but they appeared to do very little at this Reynolds number.
At the higher Reynolds number of 50,000, the low-FSTI case was strongly separated on the downstream portion of the suction surface. The separation zone was eliminated when the turbulence level was increased to 8–9%. Vortex generators were added to the suction surface of the low-FSTI case. In this instance, the vortices were able to provide the mixing needed to reestablish flow attachment.
This paper shows that massive separation at very low Reynolds numbers (25,000) is persistent, in spite of elevated FSTI and added vortices. However, at a higher Reynolds number, there is opportunity for flow reattachment either with elevated freestream turbulence or with added vortices. This may be the first documentation of flow behavior at such low Reynolds numbers. Though undesirable to operate under these conditions, it is important to know what to expect and how performance may be improved if such conditions are unavoidable.
Transient Analyses of Conjugate Heat Transfer of a First Stage Rotor Blade in Start-Up and Shut-Down
Authors: Takahashi Toshihiko , Watanabe Kazunori , Takahashi Takeshi 
Published: July 2014

In order to contribute to the life assessment of the first stage rotor blade, transient analyses of heat transfer in the start-up and shut-down of a power generation gas turbine (GT) were conducted by thermal conjugation inside and outside the blade, which consist of thermal convection and heat conduction. Characteristic diagrams in a hot start and a normal shut-down that simulate an actual plant were used to set the numerical conditions.
The characteristics of the predicted blade temperature distributions were classified into two regions for load and no-load operation. In the no-load operation in which conduction heat transfer was dominant, the temperatures of the leading and the trailing edges changed drastically and the gradient of the temperature on the blade root increased substantially after ignition. In the load operation, the configuration of the blade temperature profile remained similar over half load.
It was possible to use the predictions to estimate stress and creep strain, which are demanded for the life assessment of the blade, from the start-up to the shut-down.
Disintegration of Oil Jets Emerging From Axial Passages at the Face of a Rotating Cylinder
Authors: Glahn A. , Blair M. F. , Allard K. L. , Busam S. , Schäfer O. , Wittig S. 
Published: July 2014

A fundamental study has been performed to examine the disintegration of oil films emerging from axial passages at the face of a rotating cylinder. The investigation has been conducted in parallel to a similar study on atomization processes at rotating radial holes (Glahn et al. 2001) and has used the same approaches in simulating one of the droplet generation sources in aero-engine lubrication systems. Both papers aim to contribute to the establishment of a database that can be used for the development of droplet generation models directly applicable to engine conditions. As with the parallel investigation, the near-term objectives of fundamental oil film disintegration studies are (i) to determine droplet sizes under relevant aero-engine bearing compartment operating conditions, and (ii) to measure individual droplet diameter/velocity relationships. The long-term objective is to incorporate this information into advanced design systems such as CFD-based tools.
In the present study, flow visualization has been used to identify the dominant disintegration processes. Droplet diameters and velocities have been obtained for relevant engine operating conditions. Data are presented in terms of both characteristic diameters and size-class resolved droplet velocities and flow angles. A comparison of droplet sprays measured in the present study with those generated by disintegration of oil films at the rim of a rotating disk (Glahn at al. 2000) has been enabled by introducing non-dimensional parameters for atomization products and operating conditions.
The Flow Structure in Rotating Hollow Shafts With Radial Inflow and Axial Throughflow
Authors: Brillert D. , Reichert A. W. , Simon H. 
Published: July 2014

Modern heavy-duty gas turbines operate with high turbine inlet temperatures and thus require complex secondary air systems to ensure that blades and vanes are supplied with the necessary amount of cooling air. Low-emission gas turbines with a high thermal efficiency require minimum amounts of cooling and sealing air which means that secondary air systems must be designed with extreme accuracy.
In previous papers, the secondary air system of Siemens Vx4.3A gas turbines and the calculation method used for their design were introduced. This paper deals with the calculation of the flow in cooling air passages in rotating hollow shafts with axial throughflow. The paper starts with a derivation of basic equations and a brief review of the work on this topic described in the literature. Then on the basis of these basic equations a simple one–dimensional model is described to predict the three–dimensional flow (losses, flow deflection) in the rotating hollow shafts for different massflow rates. The calculation system is completed by matching the correlations of the simple one–dimensional model to the results of the numerical simulations.
Thermo-Economic Analysis of an Intercooled, Reheat and Recuperated Gas Turbine for Cogeneration Applications: Part II — Part-Load Operation
Authors: Bhargava R. , Negri di Montenegro G. , Peretto A. 
Published: July 2014

The knowledge of off-design performance for a given gas turbine system is critical particularly in applications where considerable operation at low load setting is required. This information allows designers to ensure safe operation of the system and determine in advance thermo-economic penalty due to performance loss while operating under part-load conditions.
In this paper, thermo-economic analysis results for the intercooled, reheat (ICRH) and recuperated gas turbine, at the part-load conditions in cogeneration applications, have been presented.
Thermodynamically, a recuperated ICRH gas turbine based cogeneration system showed lower penalty in terms of electric efficiency and Energy Saving Index over the entire part-load range in comparison to the other cycles (non-recuperated ICRH, recuperated Brayton and simple Brayton cycles) investigated.
Based on the comprehensive economic analysis for the assumed values of economic parameters, this study shows that, a mid-size (electric power capacity 20 MW) cogeneration system utilizing non-recuperated ICRH cycle provides higher return on investment both at full-load and part-load conditions, compared to the other same size cycles, over the entire range of fuel cost, electric sale and steam sale values examined. The plausible reasons for the observed trends in thermodynamic and economic performance parameters for four cycles and three sizes of cogeneration systems under full-load and part-load conditions have been presented in this paper.
Heavy Fuel Operation at Limay Bataan Power Station
Authors: Basler Benno , Marx Detlef 
Published: July 2014

The Limay Bataan Power station, a 600 MW combined cycle, is now in its 8th successful year of operation. Operating on this specific heavy fuel oil, which is a high viscosity, high ashbearing heavy fuel residue from the refinery at Limay, requires a skilled and experienced crew as the quality of fuel was subject to major changes which are highly relevant to the operating mode. If not treated properly, this fuel could corrode blades within a short operating period.
This paper describes the experiences gained on the fuel handling from the fuel treatment plant to the turbine and also addresses the operation of the combined cycle. Specific operating problems are discussed. The plant is fully operated and maintained by ALSTOM Power O&M Ltd with its local team that has greatly contributed to the success of the plant.
The MS 5002E: A New 2-Shaft, High Efficiency Heavy Duty Gas Turbine for Oil and Gas Applications
Authors: Aurelio Luca , Battagli Paolo , Bianchi Dino , Martin Arlie R. , Tognarelli Leonardo 
Published: July 2014

In mid-’98 it was decided to develop a new high efficiency version of the very successful MS5002 (GE Frame 5 two-shaft), to satisfy the most recent Customer requirements in terms of fuel consumption and environmental impact.
The machine was conceived considering different markets, primarily mechanical drive, but also non-Oil&Gas power generation.
Power class is 30 MW, pressure ratio is 17:1, simple cycle efficiency is over 36% and combined cycle efficiency approximately 51%.
The new model retains features that contributed to the success of its predecessors. The main ones are the full heavy-duty concept for on-site maintenance, the moderate firing temperature (compared with state of the art) for highest reliability, the two-shaft design with free power turbine for mechanical drive use, the high heat recovery capability.
Achievement of high cycle efficiency with low firing temperature is possible thanks the advanced tools used for the definition, design and optimization of airfoils, clearances, leakages and distribution of cooling flows. Aero-thermal design was largely based on state of the art 3D CFD and on sophisticated airfoil cooling techniques of the same type extensively used in aircraft engine development.
The dry-low-emissions combustion system design is derived from the GEPS DLN2.6.
A thorough testing program, including the full-scale test of the axial compressor and a full load prototype test, is planned to support development and to validate the design.
Rotordynamic and Bearing Upgrade of a High-Speed Turbocharger
Authors: Pettinato Brian C. , DeChoudhury Pranabesh 
Published: July 2014

The paper discusses the redesign of a high-speed turbocharger for improved bearing life and mechanical operation. The modifications resulted in reduced oil leakage across the end seal, reduced coke buildup at the turbine, increased thrust load capacity, and improved rotordynamics. In particular, rotordynamic stability was improved by eliminating subsynchronous vibration at the operating speed. The redesign consisted of changing the bearings from a pair of combination journal/thrust bearings to a pair of journal bearings and a double acting thrust bearing at the center of the unit. The active thrust bearing was moved away from the hot turbine end of the machine. The thrust bearing geometry was modified for increased minimum film thickness, reduced metal temperature, and increased load capacity. Inlet and drain passages were revised for better oil flow distribution. Unit rotordynamics were improved by upgrading the journal bearings from three-axial-groove to three-lobe design. The upgraded unit kept the same footprint as the original design with only piping modifications required.
Extensive analysis and testing were conducted. Testing of the original and revised turbochargers showed improvements in the redesign with reduced bearing metal temperatures and improved rotordynamic stability. Theoretical results along with test data consisting of bearing performance and vibration data of the original and modified system are presented in this paper.
Investigation of Unsteady Aerodynamic Blade Excitation Mechanisms in a Transonic Turbine Stage: Part II — Analytical Description and Quantification
Authors: Laumert Björn , Mårtensson Hans , Fransson Torsten H. 
Published: July 2014

This paper presents a study of the blade pressure perturbation levels and the resulting blade forces in a high-pressure transonic turbine stage based on 3D time dependent viscous computations. Globally, the blade pressure unsteadiness is quantified with the RMS of the pressure perturbations integrated in both time and along the blade surface. Operation point as well as spanwise variations are addressed. Locally, the relative strength of the pressure perturbation events on the vane and rotor blade surface is investigated. To obtain information about the relative strength of events related to the blade passing frequency and higher harmonics, the pressure field is Fourier decomposed in time at different radial positions along the blade arc-length. The amplitude peaks are then related to the pressure events in space-time maps.
With the help of the observations and results from the blade pressure study, the radial variations of the unsteady blade force and torque acting on a constant span blade profile section are investigated. The connection between the first and second vane passing frequency pressure amplitudes on the rotor blade surface and the resulting force and the torque amplitudes for three selected blade modes was investigated in detail. In this investigation the pressure was integrated over defined rotor blade regions to quantify local force contributions. Spanwise as well as operation point variations are addressed.
Excitation of Ring Vortex Production in Subsonic Jets by Sound Waves
Authors: Bohn Dieter E. , Balkowski Ingo 
Published: July 2014

In many technical units pressure of gaseous fluids is reduced in turbulent jets with high subsonic velocities. In addition to broadband noise of the jets individual frequencies are sometimes observed. Those frequencies are caused by formation of periodic vortex structures in the jet. In some cases vortex formation can be influenced by sound waves which are emitted upstream of the discontinuity.
This effect is been investigated experimentally at velocities between Ma = 0.3 and Ma = 0.9 in several nozzles. The effect of the excitation on the turbulence in the jet is been measured by means of a dynamic pressure probe. It is shown that the turbulent vortex formation is influenced by the sound wave over a wide frequency range. A visualization of the density field shows regular vortex structures in the jet.
The noise emission is simultaneously investigated with condenser microphones. In addition to the frequency peak at the excitation frequency an increase of the broadband jet noise level can be observed.
Crack Propagation in Gas Turbine Rotor Disks: Comparison of Experimental Results at Real Components With Fatigue Life Prediction
Authors: Maldfeld E. , Schödel M. , Berger C. 
Published: July 2014

Rotor disks of gas turbines are high stressed components and for safe life design both stress criteria and fracture mechanics are needed. Due to the forging process in rotor disks flaws have to be considered. There exists a certain detection limit, beneath no flaw size is detectable.
A comparison of predicted and observed crack propagation in a real gas turbine rotor disk with machined surface cracks is presented. The comparision of experimental crack growth behaviour and life prediction shows that the fracture mechanics analysis is conservative and that non detectable flaws within gas turbine rotor components cannot hurt safe service operation.
Local/Global Effects of Mistuning on the Forced Response of Bladed Disks
Authors: Rivas-Guerra Alejandro J. , Mignolet Marc P. 
Published: July 2014

The focus of the present investigation is on the assessment and modeling of the local (spanning only a few blades) and global (encompassing the entire disk) effects of mistuning on the forced response of bladed disks. To this end, the concept of localization is first revisited and a new measure of this effect is introduced in terms of the number of blades the mistuning of which actually affects the forced response of a central blade. Using this new metric, it is demonstrated that high responding blades typically exhibit a high level of localization and that the reverse is not true. Thus, localization is not only disk dependent but also varies from blade-to-blade on the same disk.
This observation is then used to validate a partial mistuning approach to the determination of the maximum amplitude of response over the entire population of disks. The results of this study indicate that the largest amplification due to mistuning occurs at very strong blade-to-blade coupling levels, at the contrary of a general perception, but is associated with extremely large mistuning levels.
Finally, the above phenomenological observations are used to devise a modeling technique of both local and global components of mistuning. An example of application is presented that demonstrates the high accuracy of this approach through the entire blade-to-blade coupling domain.
Nature of Vibratory Waves in Bladed Disks
Authors: Klompas Nicholas 
Published: July 2014

An elemental explanation of the longstanding puzzler, peak splitting, is advanced and correlated with published experimental results. The peaks are shown to represent two singular speeds of a traveling wave, at each of which a portion of the blades jump from subcritical to supercritical response, or vice versa. Only one blade, of two with slightly different natural frequency and spaced approximately 90 deg apart, passes through full resonant condition in each jump. Interaction with engine whirl is produced.
Aeroengine vibrations associated with bladed disk flexing/whirl interaction are examined:
• A nonconservative, either stabilizing or destabilizing, inertial force due to linear flexing is introduced.
• Previous definition of a nonlinear friction induced limit cycle, attendant to the interlocked shroud enabling the high-bypass turbofan, is now reviewed and completed by explanation of the necessary frictional backward driving torque.