bluuebunny/crossref_metadata_2025 huggingface dataset:
From Concept to Commercial Operation: The Tri-Fuel Injector Used for LPG and Naphtha Applications
Authors: Newman A. W. , Nixon P. S. , Wilms R. I. , Taylor D. M. , Cornwell M. D.
Published: July 2014

The tri-fuel injector is an extension of the standard dual fuel multi passage injector to cover additional fuels such as Liquid Petroleum Gas (LPG) and Naphtha at medium pumping pressure (less than 40 Bara). There is an additional passage designed for metering the LPG or Naphtha in liquid phase. The fuel system uses a non-contacting rotary pump with modern inverter technology for the pumping of these fuels.

Both tri-fuel injector and fuel system are now in commercial operation on two Tornado engines using LPG, natural gas and diesel fuels. The LPG system is operating just below 30 Bara pumping pressure, and has accumulated about 1029 operating hours on the lead engine. LPG load shedding capability has been proven on one engine. Commercial operation of the Typhoon engine on Naphtha at medium pumping pressures (< 40 Bara), with an improved tri-fuel injector, will commence in the near future.
Intermediate Temperature SOFC in Gas Turbine Cycles
Authors: Palsson Jens , Selimovic Azra , Hendriksen Peter
Published: July 2014

Operational temperature around 800°C is desirable for solid oxide fuel cells (SOFC) due to alleviation of many serious problems, associated with high temperature, i.e., high degradation rate and cost of balance of plant components along with the need for expensive ceramic interconnect. This paper is concerned with the performance of hybrid cycles employing the intermedium temperature SOFC and a gas turbine. The calculations are performed with Aspen Plus® for a system in a size of 500 kW, using methane as fuel. The simulation tool is completed by a mathematical model of the fuel cell. Cell geometry is chosen to represent the type of cells developed at Risø National Laboratory. For the stand alone SOFC, introduction of the metallic interconnect gave an overall performance improvement. A maximum electric efficiency of more than 70% for the system was calculated at low pressure ratios.
Thermodynamic Analysis of Hydrogen Combustion Turbine Cycles
Authors: Desideri Umberto , Ercolani Piergiacomo , Yan Jinyue
Published: July 2014

The “International Clean Energy System Technology Utilizing Hydrogen (World Energy Network)”: WE-NET is a research program directed at the development of the technologies needed build a hydrogen-based energy conversion system. It proposes to set up a world energy network to convert renewable energy, such as hydropower and solar energy, into a secondary and transportable form to supply the demand centers, and to make possible the utilization of existing power generation, transportation, town gas, etc.

Within the framework of this program Mitsubishi Heavy Industries, Hitachi and Westinghouse Power Corporation are working to develop an hydrogen-fueled combustion turbine system designed to meet the goals set by the WE-NET Program. The hydrogen–fueled power generation cycle will be able to satisfy the requirements of an efficiency based on the lower heating value higher than 70% and of reliability, availability and maintainability equivalent to current base-loaded natural gas-fired combined cycle. The use of hydrogen will eliminate emissions of CO2 and SOx and significantly reduce those of NOx.

This paper presents a thermodynamic analysis of some concepts of hydrogen fuelled cycles which have been studied in the WE-NET program and makes a comparison of their performance.
Using Design to Teach Thermodynamic Cycles: Designing a 250 MW Steam Power Plant Using the Rankine Cycle
Authors: Van Treuren Ken , DeJong Nicole
Published: July 2014

Power generation is increasingly important in the turbine industry. Students need exposure to the complexities of such systems as found in this design project. This project is part of the second of a two-course thermodynamic sequence designed to provide a foundation in thermodynamics and expose the students to various power generation cycles. One way to teach students the Rankine Cycle is to involve them in the various aspects of the cycle through a design project. Students, in teams of four or five, are given the task of designing a 250 MW steam power plant based on the Rankine Cycle. Calculations are made using the software of choice, usually Engineering Equation Solver (EES). Students are required to make an oral and written presentation. In addition to the presentation of calculations and graphs, an emphasis is placed on describing the general considerations of the design problem and the presentation of the unique advantages of the design. Students gain valuable experience in system optimization and better learn to justify their design decisions. Based on student evaluations the project was well received and increased student interest in the field of power generation. However, there is a need to include an economic component to the problem, and more time must be spent in class discussing typical component operating parameters.
De Minimis Approach for Meeting Anti-Degradation to Address Water Quality Issues With Respect to NPDES Discharges From New GTCC Plants
Authors: White Erik D. , Semer Robin A. , Scharre David C. , Childress Neil B.
Published: July 2014

States are required to develop and adopt anti-degradation policies and implementation procedures pursuant to federal regulations [1] to protect existing in stream water quality and water uses. States are requiring National Pollutant Discharge Elimination System (NPDES) dischargers from new sources, which could result in lowering of existing water quality, to perform an anti-degradation demonstration as part of the NPDES permit application process. These evaluations are appropriate where a proposed discharge may have a significant adverse impact on water quality. However, they are an unnecessary burden on both the permit applicant and the reviewing agency where the proposed discharge is minor relative to existing water quality. Therefore, de minimis evaluations provide a technical approach that States can use to avoid the need for, or limit the scope of, anti-degradation demonstrations where the impact at the proposed discharge is minor.

This paper provides a de minimis evaluation approach for addressing anti-degradation as part of an NPDES permit application process. The approach, which ascertains what conditions would or would not constitute a “de minimis lowering of water quality,” was recently used in support of a new combined-cycle power plant in one of the central states.
Design, Development and Testing of a Gas Turbine Steam Injection and Water Recovery System
Authors: Lupandin Vladimir V. , Romanov Victor I. , Krivutsa Villy A. , Lupandin Viktor V.
Published: July 2014

The paper describes experience gained in design and development of gas turbine units for electrical generator or mechanical drive application featuring steam injection into the gas turbine combustion chamber combined with a water recovery system from the gas turbine exhausted gases (units are known as “Aquarius”). Prototype test rigs, and test results on prototype and commercial units are discussed. These units have power output of 16 MW (“Aquarius-16”) and 25 MW (“Aquarius-25”) with efficiency of 45% and 43%, ISO respectively.

Special test rigs were designed and built to prove concept of water recovery from gas turbine exhausted gases and to study contact condenser operation over a wide range of ambient temperatures.

The first prototype test rig, comprising of SPE “Mashproekt” GT 100K gas turbine engine, 100 kW electrical generator, waste-heat recovery boiler and contact type condenser started operation in 1986.

To the Author’s knowledge there is one more plant in operation with water recovery from February 1993 located inside the “CARROZZERIA BERTONE” plant near Turin, Italy (Ennlo Macchi, Aurelio Poggio “A COGENERATION PLANT BASED ON A STEAM INJECTION GAS TURBINE WITH RECOVERY OF THE WATER INJECTED: DESIGN CRITERIA AND INITIAL OPERATING EXPERIENCE”, ASME paper 94-GT-17).

The second prototype unit, “Aquarius-25”, comprising of SPE “Mashproekt” steam injected GT 15000S gas turbine engine, waste heat recovery boiler, contact water condenser and a generator (power output of 25 MW and efficiency of 43%) is currently in operation. This unit has accumulated more than 12,000 fired hours in development tests since January 1995.

“Aquarius-16” - commercial mechanical drive unit with 16 MW power output and efficiency of 45% was built and factory tested in 1998 (more than 1600 fired hours). It was built around the SPE “Mashproekt” GT 10000S steam injected gas turbine engine. This unit is scheduled to start commercial operation at UKRGASPROM “Stavishenskaya” gas compression station (Ukraine) in 2001.
Droplet Entrainment From a Shear-Driven Liquid Wall Film in Inclined Ducts: Experimental Study and Correlation Comparison
Authors: Ebner J. , Gerendás M. , Schäfer O. , Wittig S.
Published: July 2014

The primary objective of the present study is to clarify the droplet disintegration mechanism and the film properties of liquid oil films driven by shear stress, which is induced by a co-current gas flow. This work focuses on the flow behavior within the starting length of the complex two-phase flow and the effect of inclination on the entrainment rate. Many investigations have been performed in the past to determine the droplet entrainment in the gas core for fully-developed flow conditions with respect to their relevance in pipes of power plants and various chemical engineering systems (Hewitt and Taylor, van Rossum, Ishii and Grolmes [1, 2, 3]). In more recent work the effect of inclination has been studied in detail (Lee and Mjani, Azzopardi, Azzopardi et al. [4, 5, 6]). Nevertheless, a lack of knowledge can be realized for droplet entrainment within the starting length of this complex flow type.

Thus, fundamental experiments have been carried out to provide a data base for droplet entrainment of liquid disintegrated from an oil film within its starting length at several inclination angles of the flow. The experimental results have been compared with correlations from literature. Additionally, the wall film thickness has been measured to allow a fully-coupled modelling of entrainment and liquid film properties depending on global flow parameters. Based on film Reynolds number, Weber number, a dimensionless film flow length and a modified Froude number, taking into account the angle of inclination, correlations have been developed, where those from literature are not applicable.
An Experimental Study of Liquid Film Thickness in Annular Air/Oil Flow in a Vertical Pipe Using a Laser Focus Displacement Meter
Authors: Busam S. , Ebner J. , Wittig S.
Published: July 2014

The development of modern aero-engines is leading to increased pressure and temperature levels which makes increasing demands on the engines’ safety and reliability. In particular the vent-system of the bearing chambers located in the hot section of the engine represents a critical component in the design process due to the complex two-phase flow phenomena. The air/oil mixture that is discharged out of the bearing chambers has a strong influence on the overall pressure losses and it shows locally enhanced heat transfer where oil coking or oil fires with the risk of flashback into the bearing chamber can occur.

In order to gain a deeper insight into the interacting flow of air and oil, a glass pipe test section with a inner tube diameter of 10 mm was integrated into the vent-line of the high speed bearing chamber test rig operated at the Institut für Thermische Strömungsmaschinen, University of Karlsruhe, Germany. Therewith, an experimental study of the oil film along the wall in vertical annular upflow was performed by use of a laser focus displacement meter. This instrument which was introduced by Takamasa et al. [1] allows accurate measurements of film thickness to be made in real time with a sensitivity of 2 microns and a datarate of 1.5 kilohertz.

Comprehensive measurements were conducted at two locations of the pipe 320 mm apart in flow direction. A wide range of oil and air flow rates was examined to study their impact on the local film thickness. Both fluids were heated up to the same temperature of 70°C and 100 °C, respectively, to vary the oil viscosity by a factor of 2.
Effects of Reynolds Number and Pressure Ratio on Leakage Loss and Heat Transfer in a Stepped Labyrinth Seal
Authors: Willenborg K. , Kim S. , Wittig S.
Published: July 2014

The influence of Reynolds number and pressure ratio on the operating characteristics of a stepped labyrinth seal was experimentally determined. The geometries investigated represent designs of a stepped labyrinth seal typical for modern jet engines. Heat transfer and discharge measurements were obtained for two plane models with various seal clearances. The experiments covered a range of Reynolds numbers and pressure ratios. Independent variation of Reynolds number and pressure ratio was obtained by adjusting the back pressure at the seal exit for a given pressure ratio. Dimensionless discharge coefficients, describing the sealing performance, were derived from the measured leakage rates. Pressure ratio, Reynolds number, tip geometry and seal clearance all affected the sealing performance. Finite element calculations were employed to calculate the local heat transfer coefficients from the measured wall and gas temperatures. Averaging of the local values yielded mean heat transfer coefficients and mean Nusselt numbers. The heat transfer was mainly determined by the Reynolds number. Compressibility effects on the heat transfer were observed to be very small.
Film Cooling From a Single Row of Cylindrical Angled Holes With Triangular Tabs Having Different Orientations
Authors: Nasir Hasan , Acharya Sumanta , Ekkad Srinath
Published: July 2014

The effect of discrete delta (or triangular)-shaped tabs with different orientations on the film cooling performance from a row of cylindrical holes is investigated. The holes are inclined at 35° along the streamwise direction and the tabs are located along the upstream edge of the holes. Three tab orientations are investigated: (1) tabs placed parallel to the film cooled surface covering a part of the hole; (2) tabs oriented downward at –45 degrees; and (3) tabs oriented upwards at 45 degrees. Measurements were carried out in a low-speed wind tunnel using the transient liquid crystal technique. The mainstream velocity and free-stream turbulence intensity in the low speed wind tunnel are 9 m/s and 7% respectively and the mainstream Reynolds number based on hole diameter is around 7,100. Three blowing ratios of 0.56, 1.13, and 1.7 are tested. Results show that the tabs oriented horizontally and those oriented downward provides the highest film effectiveness at blowing ratios of 0.56 and 1.13. At blowing ratio of 1.7, the horizontal tabs have the highest effectiveness. The higher effectiveness (200-300%) and higher heat transfer coefficient (25-30%) with the tabs are caused due to the generation of secondary eddies counter-rotating with respect to the kidney pair; these eddies reduce jet penetration and thus increase film cooling effectiveness.
Full-Coverage Film Cooling With Short Normal Injection Holes
Authors: Harrington Mark K. , McWaters Marcus A. , Bogard David G. , Lemmon Christopher A. , Thole Karen A.
Published: July 2014

An experimental and computational investigation was conducted on the film cooling adiabatic effectiveness of a flat plate with full coverage film cooling. The full coverage film cooling array was comprised of ten rows of coolant holes, arranged in a staggered pattern, with short, L/D = 1, normal coolant holes. A single row of coolant holes was also examined to determine the accuracy of a superposition prediction of the full coverage adiabatic effectiveness performance. Large density coolant jets and high mainstream turbulence conditions were utilized to simulate realistic engine conditions. High-resolution adiabatic effectiveness measurements were obtained using infrared imaging techniques and a large-scale flat plate model. Optimum adiabatic effectiveness was found to occur for a blowing ratio of M = 0.65. At this blowing ratio separation of the coolant jet immediately downstream of the hole was observed. For M = 0.65, the high mainstream turbulence decreased the spatially averaged effectiveness level by 12 percent. The high mainstream turbulence produced a larger effect for lower blowing ratios. The superposition model based on single row effectiveness results over-predicted the full coverage effectiveness levels.
Comparison of Cooling Film Development Calculations for Transpiration Cooled Flat Plates With Different Turbulence Models
Authors: Bohn Dieter E. , Moritz Norbert
Published: July 2014

A transpiration cooled flat plate configuration is investigated numerically by application of a 3-D conjugate fluid flow and heat transfer solver, CHT-Flow. The geometrical setup and the fluid flow conditions are derived from modern gas turbine combustion chambers. The plate is composed of three layers, a substrate layer (CMSX-4) with a thickness of 2 mm, a bondcoat (MCrAlY) with thickness 0,15 mm, and a thermal barrier coating (EB-PVD, Yttrium stabilized ZrO2) with thickness 0,25 mm, respectively.

The numerical grid contains the coolant supply (plenum), the solid body, and the main flow area upon the plate. The transpiration cooling is realized by finest drilled holes with a diameter of 0,2 mm that are shaped in the region of the thermal barrier coating. The holes are inclined with an angle of 30°. Two different configurations are investigated that differ in the shaping of the holes in their outlet region.

The numerical investigation focus on the influence of different turbulence models on the results. Regarding the secondary flow, the cooling film development and complex jet mixing vortex systems are analyzed. Additionally, the impact on the temperature distribution both on the plate surface and in the plate is investigated. It is shown that the choice of the turbulence model has a significant influence on the prediction of the flow structure, and, consequently, on the calculation of the thermal load of the solid body.
Influence of Freestream Turbulence Intensity on Cooling Effectiveness
Authors: Laroche E.
Published: July 2014

The objective of the study is to evaluate the potential of various turbulence models to simulate satisfactorily the influence of freestream turbulence intensity on the development of a cooling film, via a coupled computation, i.e. taking into account the full geometry (plenum, hole and main channel). Isotropic as well as anisotropic turbulence models (for the velocity as well as for the temperature fields) are tested, and an insight on the best suited closure is expected. The question of the respective influences of the various flow parameters (boundary layer characteristics, turbulent length scales, mass blowing ratios…) is also addressed. A low Reynolds number approach gives a correct estimation of the cooling effectiveness after approximately 10 hole diameters, for high or small blowing ratios, and using a k-ε model. The standard k-1 model largely underestimates the mixing in the injection region. The prediction of the injection region still needs to be improved for most configurations, but qualitatively the computation seems more than acceptable, as it exhibits the classically identified counter-rotating vortices that drive the heat transfer phenomena. The study also showed that predicting the influence of the freestream turbulence intensity requires taking into account thermal anisotropies, using an EARSMt (Explicit Algebraic Reynolds Stress Model, t being for Thermal) type model. An increase in freestream turbulence intensity was then shown to diminish the cooling effectiveness for all blowing ratios. The magnitude of the drop has still to be satisfactorily captured.
Turbine Nozzle Endwall Film Cooling Study Using Pressure Sensitive Paint
Authors: Zhang Luzeng J. , Jaiswal Ruchira Sharma
Published: July 2014

Endwall surface film cooling effectiveness was measured on a turbine vane endwall surface using the pressure sensitive paint (PSP) technique. A double staggered row of holes and a single row of discrete slots were used to supply film cooling in front of the nozzle cascade leading edges. Nitrogen gas was used to simulate film cooling flow as well as a tracer gas to indicate oxygen concentration such that film effectiveness by the mass transfer analogy could be obtained. Cooling mass flow was controlled to be 0.5 to 3.0% of the mainstream mass flow. The freestream Reynolds number was about 283000 and Mach number was about 0.11. The freestream turbulence intensity was kept at 6.0% for all the tests, measured by a thermal anemometer. The PSP was calibrated at various temperatures and pressures to obtain better accuracy before being applied to the endwall surface. Film effectiveness distributions were measured on a flat endwall surface for five different mass flow rates. The film effectiveness increased nonlinearly with mass flow rate, indicating a strong interference between the cooling jets and the endwall secondary flows. At lower mass flow ratios, the secondary flow dominated the near wall flow field, resulting in a low film effectiveness. At higher mass flow ratios, the cooling jet momentum dominated the near wall flow field, resulting in a higher film effectiveness. The comparison between hole injection and slot injection was also made.
Mist/Steam Cooling by a Row of Impinging Jets
Authors: Li X. , Gaddis J. L. , Wang T.
Published: July 2014

Closed loop steam has been chosen for cooling airfoils in heavy frame Advanced Turbine Systems (ATS) to improve efficiency. Enhanced cooling by the use of mist is considered to have potential to augment cooling by internal steam alone. Water droplets generally less than 10μm are added to 1.3 bar steam and injected through a row of four discrete round jets onto a heated surface. The Reynolds number is varied from 7500 to 22500 and the heat flux varied from 3.3 to 13.4 kW/m2. The mist increases the heat transfer coefficient along the stagnation line and downstream wanes in about 5 jet diameters. The heat transfer coefficient improves by 50 to 700 percent at the stagnation line for mist concentrations 0.75 to 3.5 percent by weight, depending on conditions. Off-axis maximum cooling occurs in most of the mist/steam flow but not in the steam-only flow. CFD simulation indicates that this off-axis cooling peak is caused by droplets’ interaction with the target walls.
Heat Transfer and Flow on the Blade Tip of a Gas Turbine Equipped With a Mean-Camberline Strip
Authors: Ameri A. A.
Published: July 2014

Experimental and computational studies have been performed to investigate the detailed distribution of convective heat transfer coefficients on the first-stage blade tip surface for a geometry typical of large power generation turbines(>100MW). In a previous work the numerical heat transfer results for a sharp edge blade tip and a radiused blade tip were presented. More recently several other tip treatments have been considered for which the tip heat transfer has been measured and documented. This paper is concerned with the numerical prediction of the tip surface heat transfer for radiused blade tip equipped with mean-camberline strip (or “squealer” as it is often called). The heat transfer results are compared with the experimental results and discussed. The effectiveness of the mean-camberline strip in reducing the tip leakage and the tip heat transfer as compared to a radiused edge tip and sharp edge tip was studied. The calculations show that the sharp edge tip works best (among the cases considered) in reducing the tip leakage flow and the tip heat transfer.
The Many Faces of Turbine Surface Roughness
Authors: Bons Jeffrey P. , Taylor Robert P. , McClain Stephen T. , Rivir Richard B.
Published: July 2014

Results are presented for contact stylus measurements of surface roughness on in-service turbine blades and vanes. Nearly 100 turbine components were assembled from four land-based turbine manufacturers. Both coated and uncoated, cooled and uncooled components were measured, with part sizes varying from 2 to 20cm. Spanwise and chordwise 2D roughness profiles were taken on both pressure and suction surfaces. Statistical computations were performed on each trace to determine centerline averaged roughness, rms roughness, and peak to valley height. In addition, skewness and kurtosis were calculated as well as the autocorrelation length and dominant harmonics in each trace. Extensive 3D surface maps made of deposits, pitting, erosion, and coating spallation expose unique features for each roughness type. Significant spatial variations are evidenced and transitions from rough to smooth surface conditions are shown to be remarkably abrupt in some cases. Film cooling sites are shown to be particularly prone to surface degradation.
Two-Equation Turbulence Models for Prediction of Heat Transfer on a Transonic Turbine Blade
Authors: Garg Vijay K. , Ameri Ali A.
Published: July 2014

Two versions of the two-equation k-ω model and a shear stress transport (SST) model are used in a three-dimensional, multi-block, Navier-Stokes code to compare the detailed heat transfer measurements on a transonic turbine blade. It is found that the SST model resolves the passage vortex better on the suction side of the blade, thus yielding a better comparison with the experimental data than either of the k-ω models. However, the comparison is still deficient on the suction side of the blade. Use of the SST model does require the computation of distance from a wall, which for a multi-block grid, such as in the present case, can be complicated. However, a relatively easy fix for this problem was devised. Also addressed are issues such as (1) computation of the production term in the turbulence equations for aerodynamic applications, and (2) the relation between the computational and experimental values for the turbulence length scale, and its influence on the passage vortex on the suction side of the turbine blade.
Turbulence and Vorticity Effects on Stagnation Region Heat Transfer
Authors: Oo Aung N. , Ching Chan Y.
Published: July 2014

An experimental study has been performed to investigate the influences of freestream turbulence, including the vorticity field, on the stagnation region heat transfer. A heat transfer model with a cylindrical leading edge was tested in a low speed wind tunnel at Reynolds numbers ranging from 67,750 to 142,250 based on leading edge diameter of the model. Grids of parallel rods were used to generate the freestream turbulence with well-defined primary vortex lines. The grids were placed at several locations upstream of the heat transfer model in orientations where the rods were perpendicular and parallel to the stagnation line. The turbulence intensity and the ratio of integral length scale to leading edge diameter were in the range of 3.93 to 11.78 % and 0.07 to 0.7, respectively. The measured heat transfer data and freestream turbulence characteristics are compared with existing correlation models. A new correlation for the stagnation line heat transfer has been developed that includes the spanwise fluctuating vorticity components.
Effect of Rib Turbulators in the First Pass on Heat Transfer Distributions in a Two-Pass Channel Connected by Two Rows of Holes
Authors: Ekkad Srinath V. , Kontrovitz David , Nasir Hasan , Pamula Gautam , Acharya Sumanta
Published: July 2014

This paper is a continued study of new internal channel cooling designs for modern gas turbine blades. In previous studies, the enhanced cooling in the second pass of a serpentine channel was achieved by a combination of impingement and crossflow-induced swirl. A holed or slotted divider wall replaced the 180° U-turn connecting the two legs of the serpentine channel. Flow from one coolant passage to the adjoining coolant passage was achieved through a series of straight and angled holes and a two-dimensional slot placed along the dividing wall. In this study, the focus is to enhance the heat transfer in the first pass of the two-pass channel using traditional rib turbulators. The effect of ribs in the first pass on the overall second pass heat transfer enhancement is compared to channels with no rib turbulators. Heat transfer distributions are compared for channels with and without ribs for three-channel flow Reynolds numbers ranging between 1.0×104 − 5.0×104. Results show that the presence of the ribs in the first pass reduces the heat transfer coefficients slightly in the second pass compared to the no-ribs channels. However, the first pass heat transfer is significantly enhanced over the case without ribs. In effect, the overall heat transfer enhancement for the combined two passes is significantly enhanced. Three different rib configurations, 90° ribs, 60° angled forward facing towards divider wall, and 60° angled backward facing away from divider wall, are studied for all Reynolds numbers and divider wall geometries. The presence of ribs in the first pass does not only decrease the enhanced heat transfer in the second pass but also provides higher heat transfer enhancement in the first pass resulting in an increase in overall heat transfer enhancement for the entire two-pass channel.
Prediction of Flow and Heat Transfer in Rotating Two-Pass Rectangular Channels With 45° Rib Turbulators
Authors: Al-Qahtani Mohammad , Jang Yong-Jun , Chen Hamn-Ching , Han Je-Chin
Published: July 2014

Numerical predictions of three-dimensional flow and heat transfer are presented for a rotating two-pass rectangular channel with 45° rib turbulators and channel aspect ratio of 2:1. The rib height-to-hydraulic diameter ratio (e/Dh) is 0.094 and the rib-pitch-to-height ratio (P/e) is 10. Two channel orientations are studied: β = 90° and β = 135° corresponding to the mid-portion and the trailing edge regions of a turbine blade, respectively. The focus of this study is twofold; namely, to investigate the effect of the channel aspect ratio and the channel orientation on the nature of the flow and heat transfer enhancement. A multi-block Reynolds-Averaged Navier-Stokes (RANS) method was employed in conjunction with a near-wall second-moment turbulence closure. In the present method, the convective transport equations for momentum, energy, and turbulence quantities are solved in curvilinear, body-fitted coordinates using the finite-analytic method. The numerical results compare reasonably well with experimental data for both stationary and rotating rectangular channels with rib turbulators at Reynolds number (Re) of 10,000, rotation number (Ro) of 0.11 and inlet coolant-to-wall density ratio (Δρ/ρ) of 0.115.
Effects of Concave Curvature on Boundary Layer Transition Under High Free-Stream Turbulence Conditions
Authors: Schultz Michael P. , Volino Ralph J.
Published: July 2014

An experimental investigation has been carried out on a transitional boundary layer subject to high (initially 9%) free-stream turbulence, strong acceleration K=ν/Uw2dUw/dxas high as9×10-6, and strong concave curvature (boundary layer thickness between 2% and 5% of the wall radius of curvature). Mean and fluctuating velocity as well as turbulent shear stress are documented and compared to results from equivalent cases on a flat wall and a wall with milder concave curvature. The data show that curvature does have a significant effect, moving the transition location upstream, increasing turbulent transport, and causing skin friction to rise by as much as 40%. Conditional sampling results are presented which show that the curvature effect is present in both the turbulent and non-turbulent zones of the transitional flow.
Turbulent Spots in Strong Adverse Pressure Gradients: Part 1 — Spot Behavior
Authors: D’Ovidio A. , Harkins J. A. , Gostelow J. P.
Published: July 2014

The understanding of periodic laminar-turbulent transition is crucial for flows over turbomachinery blading. Most turbomachinery blades are swept by turbulent wakes from upstream blading and recent works on transition in turbomachinery have attempted to study — and eventually predict — the nature of boundary layer transition induced by these wakes. This work reports on the characteristics of turbulent spots in strong adverse pressure gradients. In Part I the spot behavior is described. Phase-averaged velocity traces, velocity perturbation and disturbance level contours performed at two Reynolds numbers are described. In Part II (a companion paper) the spot propagation and spreading rates are reported. These experimental data are required for validating or modifying existing correlations for transition length prediction.
Improved Prediction of Turbomachinery Flows Using Near-Wall Reynolds-Stress Model
Authors: Gerolymos G. A. , Neubauer J. , Sharma V. C. , Vallet I.
Published: July 2014

In this paper an assessment of the improvement in the prediction of complex turbomachinery flows using a new near-wall Reynolds-stress model is attempted. The turbulence closure used is a near-wall low-turbulence-Reynolds-number Reynolds-stress model, that is independent of the distance-from-the-wall and of the normal-to-the-wall direction. The model takes into account the Coriolis redistribution effect on the Reynolds-stresses. The 5 mean flow equations and the 7 turbulence model equations are solved using an implicit coupled O(Δx3) upwind-biased solver. Results are compared with experimental data for 3 turbomachinery configurations: the ntua high subsonic annular cascade, the nasa_37 rotor, and the rwth 1½ stage turbine. A detailed analysis of the flowfield is given. It is seen that the new model that takes into account the Reynolds-stress anisotropy substantially improves the agreement with experimental data, particularly for flows with large separation, while being only 30% more expensive than the k – ε model (thanks to an efficient implicit implementation). It is believed that further work on advanced turbulence models will substantially enhance the predictive capability of complex turbulent flows in turbomachinery.
On the Performance of Gas Turbine Secondary Air Systems
Authors: Foley Andrew
Published: July 2014

The paper proposes a straightforward technique to quantify the performance of a gas turbine secondary air system. By recognising the air system as a component in its own right and performing the calculations suggested the systems engineer should be better able to develop and optimise a given air system. The effect of any requested compromise can also be better quantified to other component groups.
Approximate Solutions for Flow and Heat Transfer in Pre-Swirl Rotating-Disc Systems
Authors: Karabay Hasan , Wilson Michael , Owen J. Michael
Published: July 2014

The paper presents approximate solutions of the momentum-integral equations for swirling flow in a rotating cavity, which is used to model a cover-plate pre-swirl rotating-disc system in a gas-turbine engine. The solutions give the variation of Cm, the moment coefficient on the rotating discs, with βp, the pre-swirl ratio of the cooling air. Cm decreases from the free-disc value at βp = 0 to zero at βp = βp,crit, and becomes negative when βp > βp,crit. Using the Reynolds analogy, the theoretical distribution of Cm is used to calculate Nuav, the average Nusselt number on the heated disc. This shows that Nuav has a minimum value when βp = βp,crit.

The approximate solutions of Cm and Nuav are compared with computed values obtained using an axisymmetric elliptic solver. For most of the conditions considered, the theoretical values of Cm are in good agreement with the computed values. However, unlike the approximate solutions, the computed values of Cm show some dependency on the coolant flow rate. There is reasonable agreement between the theoretical and computed distribution of Nuav provided βp < βp,crit. Near βp,crit there are discontinuities in the computed values, and for larger values of βp, where the Reynolds analogy may be invalid, the theoretical and computed variations of Nuav tend to diverge.
A Prognostic Modeling Approach for Predicting Recurring Maintenance for Shipboard Propulsion Systems
Authors: Kacprzynski Gregory J. , Gumina Michael , Roemer Michael J. , Caguiat Daniel E. , Galie Thomas R. , McGroarty Jack J.
Published: July 2014

Accurate prognostic models and associated algorithms that are capable of predicting future component failure rates or performance degradation rates for shipboard propulsion systems are critical for optimizing the timing of recurring maintenance actions. As part of the Naval maintenance philosophy on Condition Based Maintenance (CBM), prognostic algorithms are being developed for gas turbine applications that utilize state-of-the-art probabilistic modeling and analysis technologies. Naval Surface Warfare Center, Carderock Division (NSWCCD) Code 9334 has continued interest in investigating methods for implementing CBM algorithms to modify gas turbine preventative maintenance in such areas as internal crank wash, fuel nozzles and lube oil filter replacement. This paper will discuss a prognostic modeling approach developed for the LM2500 and Allison 501-K17 gas turbines based on the combination of probabilistic analysis and fouling test results obtained from NSWCCD in Philadelphia. In this application, the prognostic module is used to assess and predict compressor performance degradation rates due to salt deposit ingestion. From this information, the optimum time for on-line waterwashing or crank washing from a cost/benefit standpoint is determined.
Predictive Emission Monitoring Model for LM1600 Gas Turbines Based on Neural Network Architecture Trained on Field Measurements and CFD Data
Authors: Botros K. K. , Price G. R. , Kibrya G.
Published: July 2014

A Predictive Emission Monitoring (PEM) model has been developed based on an optimized Neural Network (NN) architecture which takes 8 fundamental parameters as input variables. The model predicts both NO and NOx as output variables. The NN is initially trained using a combination of two sets of data: a) measured data at various loads from an LM1600 gas turbine installed at one of the compressor stations on TransCanada Transmission system in Alberta, Canada, b) data generated by a Computational Fluid Dynamics (CFD) at different operating conditions covering the range of the engine operating parameters spanned over one year. The predictions of NOx by CFD employed the ‘flamelet’ model and a set of 8 reactions including the Zeldovich mechanism for thermal NOx along with an empirical correlation for prompt NOx formation. It was found that a Multi Layer Perceptron type Neural Network with two hidden layers was the optimum architecture for predicting NO levels with a maximum absolute error of around 7%, mean absolute error of 2.3% and standard deviation of 1.97%. The model is easy to implement on the station PLC. A set of one year data consisting of 2804 cases was submitted to the above optimized NN architecture with varying ambient temperature from –29.9 °C to 35.7 °C and output power from 570 kW to 16.955 MW. This gave consistent contours of NO levels. As expected, NN architecture shows that NO increases with increasing power or ambient temperature.
VECTRA™ Power Turbine Development Program
Authors: deBeer Bruce R. , Nye David A.
Published: July 2014

Dresser-Rand developed the VECTRA-40 power turbine specifically for the LM2500+ gas generator. This “clean sheet of paper” design uses some of the best features from both aeroderivative and heavy duty gas turbines. After the design phase was complete, an extensive development program was undertaken to confirm that both the mechanical and aerodynamic design objectives were met. Two units were built, instrumented, and tested to full load. In addition, several components were rig tested to verify stiffness, natural frequency, or operating characteristics. Finally, some events that could not be physically tested, such as blade out response, were tested virtually.

During development testing, the power turbine was extensively instrumented with state-of-the-art sensors to verify the mechanical design and aerodynamic performance of the VECTRA. A PC based data acquisition system (DAQ) was constructed to simultaneously acquire and record over 1000 individual channels of data. Instrumentation was installed to record the mechanical responses and operating temperatures of all rotating components, as well as critical stationary components. Other groups of instrumentation were used to verify flowpath performance, cooling air distribution, and lubrication system operation. The physical devices connected to the DAQ system ranged from industrial transducers and signal conditioners to an innovative external telemetry system for rotating thermocouples and dynamic strain gages.

The VECTRA is a high speed power turbine that was initially designed for mechanical drive applications. However recent component testing and full load testing of two units in generator drive packages have demonstrated that it is also well suited for power generation applications.
Series or Parallel Arrangement in a Two-Unit Compressor Station
Authors: Ohanian Sebouh , Kurz Rainer
Published: July 2014

This paper discusses how to determine the arrangement of compressors in a two-unit gas pipeline station where there is no standby unit. The compressors are driven by variable speed drivers such as gas turbines or variable frequency electric motors.

Both series and parallel arrangements are analyzed in a transient simulation mode to determine which operation mode is more advantageous.

Among the assumptions in this paper are the performance characteristics of the compressor. It will be outlined how these performance characteristics influence the conclusions.
Increase of Global Efficiency in Pipeline Compression Station: A Challenge for the Future
Authors: Pucci Marco , Guzzardi Maria Germana , Saccardi Giovanni
Published: July 2014

The article, after a short market analysis of the gas sector, deals with the subjects relative to the increase of efficiency and at the same time to the minimisation of global environmental impact in pipeline gas compression stations with gas turbine driver.

In the second part, the article deals with the analysis of one of the new possible solutions in new or repowering/revamping projects of pipeline compression stations: the utilization of gas-steam combined cycle technology, focusing attention on the key issues of this kind of industrial plants, such as high availability and high flexibility in gas compressor, safety operation, possibility of remote operation and easy maintenance.

In particular, the article will analyze a specific project: the Transitgas Ruswil Extension Compressor Project, an example of implementation of these new particular plants, which we do believe to be an answer to the future challenge of optimisation of global efficiency.
Effects of Wheel-Shaft-Fluid Coupling and Local Wheel Deformations on the Global Behavior of Shaft Lines
Authors: Lornage D. , Chatelet E. , Jacquet-Richardet G.
Published: July 2014

Rotating parts of turbomachines are generally studied using different uncoupled approaches. For example, the dynamic behavior of shafts and wheels are considered independently and the influence of the surrounding fluid is often taken into account in an approximate way. These approaches, while often sufficiently accurate, are questionable when wheel-shaft coupling is observed or when fluid elements are strongly coupled with local structural deformations (leakage flow between wheel and casing, fluid bearings mounted on a thin-walled shaft, etc.). The approach proposed is a step toward a global model of shaft lines. The whole flexible wheel-shaft assembly and the influence of specific fluid film elements are considered in a fully three-dimensional model.

In this paper, the proposed model is first presented and then applied to a simple disc-shaft assembly coupled with a fluid film clustered between the disc and a rigid casing. The finite element method is used together with a modal reduction for the structural analysis. As thin fluid films are considered, the Reynolds equation is solved using finite differences in order to obtain the pressure field. Data are transferred between structural and fluid meshes using a general method based on an interfacing grid concept. The equations governing the whole system are solved within a time marching procedure.

The results obtained show significant influence of specific 3D features such as disc-shaft coupling and local disc deformations on global behavior.
Finite Element and Transfer Matrix Methods for Rotordynamics: A Comparison
Authors: Nikolajsen Jorgen L.
Published: July 2014

A quantitative comparison is made between the Finite Element Method and four variants of the Transfer Matrix Method, as applied to free vibration analysis of rotor systems. The results are as follows: The Finite Element Method is the most robust method and can identify the largest number of natural frequencies. The finite-element-based Transfer Matrix Method is the most accurate method and uses the least amount of memory. The Polynomial Transfer Matrix Method is the fastest. The Riccati Transfer Matrix Method performed well but did not live up to its superior reputation. The Lund Transfer Matrix Method also performed well except on processing speed where it fell far short of the other methods.
Using Guided Balls to Auto-Balance Rotors
Authors: Wettergren Håkan L.
Published: July 2014

By using balancing balls constrained to move in a circular groove filled with oil, the vibration of rotating machinery can, under certain circumstances, be reduced. This paper shows that the damping from the oil reduces the instability region, i.e. the conditions when the balancing balls don’t find their equilibrium positions. However, the instability region seems to increase with increasing number of balancing balls.

The critical ball damping ratio is highest just above the natural frequency and then rapidly decreases. Consequently, since the region between instability and critical damping is quite small, the ball damping should be made as small as possible without getting too close to the instability threshold.

Bearing damping has a large effect on the instability region. High bearing damping will suppress the instability.

The time it takes to reach the asymptotically stable position seems to increase with increasing number of balls. Keeping this time low is one of the most important things when designing a balancing ring.
Ritz Series Analysis of Rotating Machinery Incorporating Timoshenko Beam Theory
Authors: Zirkelback Nicole L. , Ginsberg Jerry H.
Published: July 2014

A shaft with attached rigid disks is modeled as a rotating Timoshenko beam supported by general compliant, nonconservative bearing supports. The continuous shaft-disk system is described with kinetic and potential energy functionals that fully account for transverse shear, translational and rotatory inertia, and gyroscopic coupling. Ritz series expansions are used to describe the flexural displacements and cross-sectional rotations about orthogonal fixed axes. The equations of motion are derived from Lagrange’s equations and placed in a state-space form that preserves the skew-symmetric gyroscopic matrix, as well as the cross-coupling displacement and velocity coefficient matrices describing the effects of bearings. Both the general and adjoint eigenproblems for the nonsymmetric equations are solved. Bi-orthogonality conditions lead to the ability to evaluate dynamic response via modal analysis. Two examples, which show close agreement with prior analyses of critical speeds, demonstrate the ease with which the method may be applied.