bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Blade Wakes on the Performance of Inter-Turbine Diffusers
Authors: Dominy Robert G. , Kirkham David A.
Published: February 2015

Inter-turbine diffusers provide continuity between H.P. and LP turbines whilst diffusing the flow upstream of the L.P. turbine. Increasing of the mean turbine diameter offers the potential advantage of reducing the flow factor in the following stages leading to increased efficiency. The flows associated with these inter-turbine diffusers differ from those in simple annular diffusers both as a consequence of their high-curvature S-shaped geometry and of the presence of wakes created by the upstream turbine. It is shown that even the simplest two-dimensional wakes result in significantly modified flows through such ducts. These introduce strong secondary flows demonstrating that full three-dimensional, viscous analysis methods are essential for correct performance modelling.
Calculation of Three-Dimensional Viscous Flow in Hydrodynamic Torque Converters
Authors: Schulz H. , Greim R. , Volgmann W.
Published: February 2015

A numerical method for calculating threedimensional, steady or unsteady, incompressible, viscous flow is described. The conservation equations for mass and momentum and the equations of the kε-turbulence model are solved with a finite volume method on nonorthogonal boundary-fitted grids. The method employs cell-centered variable arrangement and Cartesian velocity components. The SIMPLE-algorithm is used to calculate the pressure and to enforce mass conservation. The computer code is vectorizable as far as possible to achieve an optimal performance on modern vector computers. Results of steady flow calculations in the guide vane, the pump rotor and the turbine rotor and of the unsteady interaction simulation of the pump and the turbine of a one-stage one-phase non-automotive hydrodynamic torque converter are presented.
Wake-Induced Unsteady Flows: Their Impact on Rotor Performance and Wake Rectification
Authors: Adamczyk J. J. , Celestina M. L. , Chen Jen Ping
Published: February 2015

The impact of wake-induced unsteady flows on blade row performance and the wake rectification process is examined by means of numerical simulation. The passage of a stator wake through a downstream rotor is first simulated using a three dimensional unsteady viscous flow code. The results from this simulation are used to define two steady state inlet conditions for a three dimensional viscous flow simulation of a rotor operating in isolation. The results obtained from these numerical simulations are then compared to those obtained from the unsteady simulation both to quantify the impact of the wake-induced unsteady flow field on rotor performance and to identify the flow processes which impact wake rectification. Finally, the results from this comparison study are related to an existing model which attempts to account for the impact of wake-induced unsteady flows on the performance of multistage turbomachinery.
Unsteady 3D Flow in a Single-Stage Transonic Fan: Part II — Unsteady Stator Exit Flow Field
Authors: Cherrett M. A. , Bryce J. D. , Ginder R. B.
Published: February 2015

Detailed unsteady aerodynamic measurements have been taken in a single-stage transonic fan with a very high stage-hub loading. 2D dynamic yawmeter probes, capable of measuring mean levels and fluctuations in stagnation pressure, static pressure and yaw angle have been traversed at rotor exit and downstream of the stator, along with several types of pneumatic 3D probe. Part I* describes measurements taken at rotor exit. This paper, Part II, describes measurements taken at stator exit when the fan was operating at near peak efficiency, on the design speed characteristic. The measurements indicate the effects of rotor-stator interaction on the development of the viscous endwall-corner flows at the hub and casing. In addition, they illustrate that significant changes in stagnation pressure level occur within much of the stator exit flow field during the rotor passing cycle.
Regenerator Effectiveness During Transient Operation
Authors: Beck Douglas Stephen
Published: February 2015

The transient response of regenerators is considered. The time required for regenerators to reach steady-state effectiveness is determined. Theoretical results are presented. Also, experimental results that confirm the theory are presented. It is concluded that the time required for a regenerator to reach steady-state effectiveness is τss∼NTU1+hA′1+As′CRAT4As′1-SCkN×ρcDH2RNuH1-pp This expression indicates how regenerator cores can be designed for fast effectiveness response. In dimensionless form, τXss*∼1 where τXss* is the greater of the cool-flow and warm-flow heat-capacity rates, times τss, divided by the heat capacity of the core material. This expression gives a general method for calculation of the effectiveness-response time of regenerator cores. The dimensionless response time is nearly constant with variations in regenerator system-parameter values. Also, for sufficiently high dimensionless core-rotation rates, the dimensionless response time is independent of dimensionless core-rotation rate.
Three-Dimensional Navier-Stokes Analysis and Redesign of an Imbedded Bellmouth Nozzle in a Turbine Cascade Inlet Section
Authors: Giel P. W. , Sirbaugh J. R. , Lopez I. , Van Fossen G. J.
Published: February 2015

Experimental measurements in the inlet of a transonic turbine blade cascade showed unacceptable pitchwise flow non-uniformity. A three-dimensional, Navier-Stokes computational fluid dynamics (CFD) analysis of the imbedded bellmouth inlet in the facility was performed to identify and eliminate the source of the flow non-uniformity. The blockage and acceleration effects of the blades were accounted for by specifying a periodic static pressure exit condition interpolated from a separate three-dimensional Navier-Stokes CFD solution of flow around a single blade in an infinite cascade. Calculations of the original inlet geometry showed total pressure loss regions consistent in strength and location to experimental measurements. The results indicate that the distortions were caused by a pair of streamwise vortices that originated as a result of the interaction of the flow with the imbedded bellmouth. Computations were performed for an inlet geometry which eliminated the imbedded bellmouth by bridging the region between it and the upstream wall. This analysis indicated that eliminating the imbedded bellmouth nozzle also eliminates the pair of vortices, resulting in a flow with much greater pitchwise uniformity. Measurements taken with an installed redesigned inlet verify that the flow non-uniformity has indeed been eliminated.
Advanced Aircraft Engines Under 7MW
Authors: Vogt Robert L.
Published: February 2015

Advanced turboprop/turboshaft aircraft engines now under development will out perform the current fleet in specific power, specific weight and specific fuel consumption. These new engines will have lower costs per unit power in constant dollars and will have considerably reduced life-cycle-costs. This paper discusses the trade-offs involving one and two spools and the relative importance of inefficiencies. Current development activities are identified and references cited from the underlying enabling core engine program.
Marinized Industrial Gas Turbine for HSLC Marine Propulsion
Authors: Waldhelm Chris M.
Published: February 2015

Advancements in high speed, light craft (HSLC) sea transportation require a main propulsion system that provides relatively high specific power with a minimum of weight/space. For commercial operations, the economics of the propulsion system are considered a key criterion in power plant selection. Marinizing a durable second generation industrial gas turbine, like the Solar Taurus® marine gas turbine, is ideally suited to satisfy the combination of the high vessel speed objective and the operating cost economic justification of commercial HSLC.

Since the Taurus gas turbine has evolved from an earlier marine propulsion gas turbine and is in offshore platform service using materials and coatings resistant to marine environments, certification for marine prime propulsion concentrated primarily on operating inclination dynamic loading and the interfaces with the auxiliary support systems.

With its high power to weight ratio, reliable performance, competitive first cost, and low operating costs, the Taurus marine industrial gas turbine can be further enhanced by recuperation and variable nozzle designs improving specific fuel consumption and part load efficiencies beyond other alternatives.
Fuel Manifold Air Purge System for Allison 501-K17/K34 Marine Gas Turbine Engines
Authors: Russom Dennis M. , Daransky Thomas E.
Published: February 2015

Fuel nozzle fouling has plagued the U.S. Navy’s shipboard Allison 501-K engine program since its inception. Symptoms of fouled fuel nozzles include turbine starting problems, premature combustion liner burnthrough, and damage to turbine stationary and rotating blades. Nozzle fouling occurs during normal turbine operation and when a turbine shutdown is initiated. The fuel manifold air purge system was developed with a goal to reduce the incidence of fuel nozzle fouling. This system is active only when a shutdown is initiated and consequently only provides relief to the fouling that occurs during that time. Extensive testing has verified the effectiveness of the system. This paper describes the air purge system, it’s associated testing effort, and future program plans.
Non-Axisymmetric Endwall Profiling in the HP NGV’s of an Axial Flow Gas Turbine
Authors: Rose Martin G.
Published: February 2015

The Nozzle Guide Vanes (NGV’s) of an axial gas turbine generate circumferential non-uniformities in static pressure after their trailing edges. This paper aims to show that these non-uniformities can be removed locally by re-shaping the hub endwall. The ultimate objective is to improve engine performance by cutting the leakage of coolant from the disc rim seal. The technique is demonstrated theoretically using 3D viscous CFD. The required endwall shape is non-axisymmetric and is generated parametrically by altering a calculation grid for an existing NGV. The results show a reduction of the static pressure non-uniformities by 70%. Other favourable effects are also predicted and are commented upon.
Interaction Between Inlet Boundary Layer, Tip-Leakage and Secondary Flows in a Low-Speed Turbine Cascade
Authors: Chan J. K. K. , Yaras M. I. , Sjolander S. A.
Published: February 2015

An experiment has been conducted in a large-scale linear turbine cascade to examine the interaction between the inlet endwall boundary layer, tip-leakage and secondary flows. Detailed flow field measurements have been made upstream and downstream of the blade row for two values of inlet boundary layer thickness (δ*/c of about 0.015 and 0.04) together with three values of tip clearance (gap heights of 0.0, 1.5 and 5.5 percent of blade chord). In the downstream plane, the total pressure deficits associated with the tip-leakage and secondary flows were discriminated by examining the sign of the streamwise vorticity. For this case, the streamwise vorticity of the two flows have opposite signs and this proved an effective criterion for separating the flows despite their close proximity in space. It was found that with clearance the loss associated with the secondary flow was substantially reduced from the zero clearance value, in contradiction to the assumption made in most loss prediction schemes. Further work is needed, notably to clarify the influence of relative tip-wall motion which in turbines reduces the tip-leakage flow while enhancing the secondary flow.
Development of a Fuel Air Premixer for Aero-Derivative Dry Low Emissions Combustors
Authors: Joshi Narendra D. , Epstein Michael J. , Durlak Susan , Marakovits Steven , Sabla Paul E.
Published: February 2015

An experimental program was conducted to develop premixer concepts for use in GE’s aero-derivative Marine and Industrial gas turbine engines such as the LM 1600, 2500 and 6000. These engines operate typically at pressure ratios up to 30:1. Extensive tests in 1 and 2 cup test combustors were carried out to evaluate the Double Annular Counter-Rotating Swirler (DACRS) premixers at test conditions representative of the above mentioned engines. These tests also help establish combustor design parameters. Single digit NOx emissions were measured at engine operating conditions with the DACRS II and III premixers. Premixer interactions and their effects on Lean Blow Out were also studied.
Mars SoLoNOx: Lean Premix Combustion Technology in Production
Authors: Etheridge C. J.
Published: February 2015

Solar Turbines has applied it’s SoLoNOx lean premix combustion technology to the Mars 100S (10.5 MW, 14,100 hp ISO) and Mars 90S (9.4 MW, 12600 hp ISO) gas turbine engines and now offers engines with guaranteed NOx and CO emissions less than 42 and 50 ppmv respectively and with near term expectations of offering NOx emissions below 25 ppmv when operating on natural gas fuels. The development has been ongoing since January 1990 and includes a field demonstrator engine which is running on a gas pipeline in the North West of USA.

This paper introduces the basic design of the Mars SoLoNOx combustion system and presents some of the unique characteristics found with this lean premix technology during the program.
A Cost Effective Process for Silicon Nitride Engine Components
Authors: Garvey Garry J. , Sibold Jack D.
Published: February 2015

Silicon Nitride (Si3N4) ceramics offer tremendous material advantages for automotive and other high strength, high thermal shock resistance applications. Yet while the need for such a material continues to rise, the high cost of silicon nitride components remains a significant barrier to market acceptance. It was determined that market acceptance hinged on achieving three goals: high flexural strength (i.e. 4 pt. MOR >525 MPa), high reliability (i.e. Weibull modulus >15) and a spray-dried body cost of <$13.00/kg. To address this need, GTC/Coors licensed a prototype process from Eaton for making Sintered Reaction-Bonded Silicon Nitride (SRBSN) that offered the potential for low cost manufacturing. This paper describes the process optimization that took place to adapt this prototype process to GTC/Coors existing manufacturing technology base. It also presents the material properties and baseline cost-efficiency goals that were achieved.
Relative Performance Comparison Between Baseline Labyrinth and Dual Brush Compressor Discharge Seals in a T-700 Engine Test
Authors: Hendricks Robert C. , Griffin Thomas A. , Kline Teresa R. , Csavina Kristine R. , Pancholi Arvind , Sood Dvandra
Published: February 2015

In separate series of YT-700 engine tests, direct comparisons were made between the forward-facing labyrinth and dual-brush compressor discharge seals. Compressor speeds to 43 000 rpm, surface speeds to 160 m/s (530 ft/s), pressures to 1 MPa (145 psi), and temperatures to 680 K (765°F) characterized these tests. The wear estimate for 46 hr of engine operations was less than 0.025 mm (0.001 in.) of the Haynes 25 alloy bristles running against a chromium-carbide-coated rub runner. The pressure drops were higher for the dual-brush seal than for the forward-facing labyrinth seal and leakage was lower-with the labyrinth seal leakage being 2½ times greater-implying better seal characteristics, better secondary airflow distribution, and better engine performance (3 percent at high pressure to 5 percent at lower pressure) for the brush seal. (However, as brush seals wear down (after 500 to 1000 hr of engine operation), their leakage rates will increase.) Modification of the secondary flow path requires that changes in cooling air and engine dynamics be accounted for.
Reynolds Stresses and Dissipation Mechanisms in a Turbine Tip Leakage Vortex
Authors: Moore John , Moore Joan G. , Heckel Scott P. , Ballesteros Rafael
Published: February 2015

Reynolds stresses and mean flow velocities were measured throughout a tip leakage vortex in a large scale linear turbine cascade using hot-wire anemometry. An X-wire endflow probe was rotated about the probe axis using a computer controlled stepper motor. An improved solution procedure reduced the approximations involved in the Reynolds stress analysis. Measurements were made on a plane just upstream of the blade trailing edge. The results show the turbulence intensity, the turbulence kinetic energy, and all six Reynolds stresses. The non-isotropy of the Reynolds normal stresses is also presented. Turbulence production rates are evaluated and the contributions to the dissipation of mean kinetic energy from Osborne Reynolds’ nine terms are found. The turbulence production due to the strain rate of the secondary flow is also considered.
Installation of a Turbine Stage in the Pyestock Isentropic Light Piston Facility
Authors: Hilditch M. A. , Fowler A. , Jones T. V. , Chana K. S. , Oldfield M. L. G. , Ainsworth R. W. , Hogg S. I. , Anderson S. J. , Smith G. C.
Published: February 2015

The Isentropic Light Piston Facility (ILPF) at Pyestock has been upgraded to include a single stage, high pressure turbine. All major non-dimensional parameters are accurately scaled during the 0.4s run time, enabling heat transfer and aerodynamic measurements to be made at engine representative conditions. The ILPF was previously an annular cascade facility. This paper describes the design and integration of the rotor module and the results of the commissioning tests. An important feature is a novel, patented, turbobrake which is shown to maintain the turbine at a constant speed during the run.
A Statistical Study of Gas Turbine Losses and Analysis of Causes and Optimum Methods of Prevention
Authors: Dundas Robert E.
Published: February 2015

Data on the distribution by size of generator-drive gas turbines insured by Allendale Insurance, Arkwright and Protection Mutual insurance companies is presented. Similar data on loss costs is included. The principal failure modes are shown and described. Finally, a comprehensive table outlining the causes of these failure modes, and the optimum approaches to their prevention, is given.
The Capability of Different Semianalytical Equations for Estimation of NOx Emissions of Gas Turbines
Authors: Becker T. , Perkavec M. A.
Published: February 2015

The NOx emissions of gas turbines are depending on different influences. On the one side there are the effects fixed by the gas turbine design and on the other side the ambient effects, the fuel properties and the operational conditions.

Because the NOx emissions are difficult to calculate by chemical reactions and flow calculations, some investigators developed semianalytical equations, which in their opinion contained the most important influencing factors together with some tuning factors for the actual gas turbine design and application.

This paper shows the capability of those procedures, including a new one. It compares the calculated NOx emission with measured data. The comparisons were made for one gas turbine fired with different fuels (natural gas, propane, butane, coke oven gas), as well as for different combustor inlet conditions in case of simple and regenerative cycle operation. Reference is made also for some other gas turbine models. Also full and part load operation as well as the steam injection effects are included.
A Numerical Method for the Prediction of Bladed Disk Forced Response
Authors: Berthillier Marc , Dhainaut Marc , Burgaud Franck , Garnier Vincent
Published: February 2015

A numerical method has been developed to predict the forced response of bladed disks due to a wake excitation from upstream blade rows. The structure is modelled by a 3D finite element mesh of a bladed disk segment. Using cyclic symmetry, this model provides a modal base for the rotating structure. The aerodynamic damping of the vibratory modes and the excitation pressures on the blades due to the propagation of upstream flow defects are computed separately using the same 3D unsteady Euler analysis software. A modal response solution of the aeromechanical system is then performed.

This analytical methodology has been used to study the forced response of an experimental high pressure compressor blisk. The results are analysed and compared with actual rig tests.
Validation of 3-D Euler Methods for Vibrating Cascade Aerodynamics
Authors: Gerolymos Georg A. , Vallet Isabelle
Published: February 2015

The purpose of this work is to validate a time-nonlinear three-dimensional Euler solver for vibrating cascades aerodynamics by comparison with available theoretical semi-analytical results from flat-plate cascades. First the method is validated with respect to the purely two-dimensional theory of Verdon (for supersonic flow) by computing two-dimensional vibration (spanwise constant) in linear three-dimensional cascades. Then the method is validated by comparison with the theoretical results of Namba and the computational results of He and Denton, for subsonic flow in a linear three-dimensional cascade with three-dimensional vibratory mode. Finally the method is compared with results of Chi from two subsonic rotating annular cascades of helicoïdal flat-plates. Quite satisfactory agreement is obtained for all the cases studied. A first code-to-code comparison is also presented.
The Feasibility of Heat Pipe Turbine Vane Cooling
Authors: Silverstein Calvin C. , Gottschlich Joseph M. , Meininger Matthew
Published: February 2015

This paper evaluates the basic feasibility and anticipated benefits to using heat pipe technology to cool the turbine vanes of gas turbine engines.

This concept involves fitting out the vane interior as a heat pipe, extending the vane into an adjacent heat sink and then transferring the vane incident heat through the vane to the heat sink. The baseline is an advanced military fighter engine and the bypass air is the chosen heat sink. The results of this study show a 7.2% increase in engine thrust, a 0.2% decrease in specific fuel consumption with engine weight increased by less than 1% by using this technology.
Improved Blade Profile Loss and Deviation Angle Models for Advanced Transonic Compressor Bladings: Part I — A Model for Subsonic Flow
Authors: König W. M. , Hennecke D. K. , Fottner L.
Published: February 2015

New blading concepts as used in modern transonic axial-flow compressors require improved loss and deviation angle correlations. The new model presented in this paper incorporates several elements and treats separately blade-row flows having subsonic and supersonic inlet conditions. In the first part of this paper two proved and well-established profile loss correlations for subsonic flows are extended to quasi twodimensional conditions and to custom-tailored blade designs. Instead of a deviation angle correlation a simple method based on singularities is utilized. The comparison between the new model and a recently published model demonstrates the improved accuracy in prediction of cascade performance achieved by the new model.
FT8-55 Mechanical Drive Aeroderivative Gas Turbine: Design of Power Turbine and Full-Load Test Results
Authors: Aschenbruck E. , Blessing R. , Turanskyj L.
Published: February 2015

A new, highly efficient 25-MW aero-derivative gas turbine, model FT8-55, has been developed for mechanical drive applications as a member of the FT8 gas turbine family which also includes two generator drive gas turbines, models FT8-30 and FT8-36, with power turbine speeds of 3000 rpm and 3600 rpm, respectively. For the new mechanical drive version FT8-55, the power turbine can be operated up to 5775 rpm at maximum continuous speed. All power turbines are equipped with gas generators, model GG8-1, which are derived from the most popular aero-engine in civil aviation, the JT8D.

The first part of this paper describes design features, rotor dynamics, and material selection for the three-stage power turbine PT8-55. Rotor design permits unrestricted operation in the speed range from 2500 rpm up to maximum continuous speed.

The first FT8-55 gas turbine was subjected to mechanical and performance workshop tests at different speeds and power outputs up to full-load.

The second part of the paper deals with the description of the test stand arrangement for testing complete gas turbine packages as well as measurement techniques and data evaluation. Power was absorbed by a two-stage pipeline compressor, equipped with magnetic bearings and dry gas seals, which was operated in a closed loop. Thermodynamic and mechanical test results at various speeds and loads provide evidence of a highly efficient and mechanically robust gas turbine for mechanical drive applications.
New, Rapid Techniques for Determining the Hydroperoxide Content, Oxidation Stability, and Thermal Stability of Jet Fuels
Authors: Kauffman Robert E.
Published: February 2015

New, rapid analytical techniques based on cyclic voltammetry are being developed to determine the hydroperoxide contents and the thermal and thermaloxidation stabilities of different type jet fuels (straight run, hydrotreated, JP-4, and JP-5). The techniques are performed at room temperature, use less than 1 mL of fuel, and use common solvents containing different electrolytes or reactive compounds. The cyclic voltammetric techniques were used to quantify the natural antioxidants, easily oxidizable compounds, and hydroperoxides present in different type fuels. Mathematical relationships were then developed to evaluate the potential of the voltammetric results to predict the thermal and oxidative stabilities of the jet fuels determined by high temperature oxidation and thermal stability tests.
Detailed Measurements of Three-Dimensional Flows and Losses Inside an Axial Flow Turbine Rotor
Authors: Yamamoto Atsumasa , Tomlnaga Junichi , Matsunuma Takayuki , Outa Eisuke
Published: February 2015

Detailed traverse measurements of three dimensional flows and the associated losses inside a turbine rotor passage were carried out in the rotating frame of reference by using small five hole Pitot tubes. Strong secondary flows including passage vortices, a leakage vortex and various separation vortices were found to occur in the passage, and they are significantly influenced by the rotor speed, variation of which corresponds to different test incidences and blade loadings. Loss generation process in the rotor is described in relation to the migration of low energy fluids which are driven by the various vortices and their interaction at different rotor incidences.
Numerical Study of the Internal Flow Field of a Centrifugal Impeller
Authors: Zhang Mou-jin , Gu Chuan-gang , Miao Yong-miao
Published: February 2015

The complex three-dimensional flow field in a centrifugal impeller with low speed is studied in this paper. Coupled with high–Reynolds–number k–ε turbulence model, the fully three–dimensional Reynolds averaged Navier–Stokes equations are solved. The Semi–Implicit Method for Pressure–Linked Equations (SIMPLE) algorithm is used. And the non–staggered grid arrangement is also used. The computed results are compared with the available experimental data. The comparison shows good agreement.
Experimental Identification of Dynamic Characteristics of Hydrodynamic Torque Converters and Couplings
Authors: Folchert Uwe , Menne Achim , Waller Heinz
Published: February 2015

Hydrodynamic torque converters and couplings can be components of drive systems. The knowledge of their dynamic characteristics is necessary to calculate the dynamic response of the whole system under various time dependent excitations in order to guarantee safe working. The presented mathematical description of the nonlinear behavior consists of several linear models at several operating points. For a special linear “two port” description as used in electro-technique the four state variables are measured: the torques and the rotational speeds. The mathematical models are determined through an application of identification methods. Therefore a computer controlled testing bench has been constructed. High dynamic excitations have been realized with two hydrostatic drives which can be used as motors or brakes. The hydrodynamic component (torque converter or coupling) can be excited harmonically with the aid of the driving machines. By measuring the four state variables it is possible to get the frequency response functions. They are approximated by complex rational functions. The use of an inverse Fourier transformation into the time domain allows to calculate the dynamic behavior under general transient excitations.
Durability Evaluation of Ceramic Components Using Cares/Life
Authors: Nemeth Noel N. , Powers Lynn M. , Janosik Lesley A. , Gyekenyesi John P.
Published: February 2015

The computer program CARES/LIFE calculates the time-dependent reliability of monolithic ceramic components subjected to thermomechanical and/or proof test loading. This program is an extension of the CARES (Ceramics Analysis and Reliability Evaluation of Structures) computer program. CARES/LIFE accounts for the phenomenon of subcritical crack growth (SCG) by utilizing the power law, Paris law, or Walker equation. The two-parameter Weibull cumulative distribution function is used to characterize the variation in component strength. The effects of multiaxial stresses are modeled using either the principle of independent action (PIA), the Weibull normal stress averaging method (NSA), or the Batdorf theory. Inert strength and fatigue parameters are estimated from rupture strength data of naturally flawed specimens loaded in static, dynamic, or cyclic fatigue. Application of this design methodology is demonstrated using experimental data from alumina bar and disk flexure specimens which exhibit SCG when exposed to water.
Experimental Investigation of Secondary Flows in a Low Hub-Tip Ratio Fan
Authors: Nurzia F. , Puddu P.
Published: February 2015

The paper deals with an experimental investigation of the three-dimensional flow field at the exit of a low hub/tip ratio industrial axial fan. The relative flow was evaluated with fixed hot wire probes using the multisampling and phase-locked ensemble averaging techniques. Both mean flows and secondary flows are examined for different blade loading and stagger angles. The mean flows observed indicate a large separated flow region at the hub that is accentuated at the higher stagger angle. The secondary flows are particularly strong and affect the entire flow field. Their structure and location are also modified when stagger angle and blade loading are changed. The most complex situation is observed at the hub where a change in blade loading and stagger angle results in the interaction of the trailing vortex with the separated flow region, the passage vortex and midpassage region flow.
Damage Tolerance Analysis of Compressor Blade
Authors: Mao Jinxin , Hong Olin , Wang Rongqiao , Hua Mingda
Published: February 2015

In this paper, we apply damage tolerance analysis to a certain compressor blade by finite element and fracture mechanics methods. The blade is analysed by using the isoparametric finite element with 20 nodes, its stress and displacement fields are determined, and the critical position where the crack probably initiates is located. Then the value of J–integral with different crack sizes in the critical position are computed using the 3-D J-integral program. On the basis of the fracture toughness of blade material, Je, the blade extension limit δe, and the deviation of natural frequency, Δfe, the failure criterion of the blade is discussed and the critical crack size, ae, is determined. Then according to the crack growth rate obtained from the testing, the residual life of the blade with different crack sizes is evaluated. The maximum allowable crack size, a0*, is determined using the condition that the crack would not grow to critical crack size during double overhaul periods. This value can be used to design the structure of compressor blade or to establish the criterion to judge whether a compressor blade with a crack can be used. In this way the safety and reliability of airplanes is maintained and the costs are reduced. So the damage tolerance analysis of compressor blades is practical and economical.
Behavior of Separation Bubble and Reattached Boundary Layer Around a Circular Leading Edge
Authors: Hazarika B. K. , Hirsch C.
Published: February 2015

The flow around a circular leading edge airfoil is investigated in an incompressible, low turbulence freestream. Hot-wire measurements are performed through the separation bubble, the reattachment and the recovery region till development of the fully turbulent boundary layer. The results of the experiments in the range of Reynolds numbers 1.7×103 to 11.8×103 are analysed and presented in this paper. A separation bubble is present near the leading edge at all Reynolds numbers. At the lowest Reynolds number investigated, the transition is preceded by strong low frequency oscillations. The correlation given by Mayle for prediction of transition of short separation bubbles is successful at the lower Reynolds number cases. The length of the separation bubble reduces considerably with increasing Reynolds number in the range investigated. The turbulence in the reattached flow persists even when the Reynolds number based on momentum thickness of the reattached boundary layer is small. The recovery length of the reattached layer is relatively short and the mean velocity profile follows logarithmic law within a short distance downstream of the reattachment point and the friction coefficient conforms to Prandtl-Schlichting skin-friction formula for a smooth flat plate at zero incidence.
Low NOx Premixed Combustion of MBTU Fuels Using the ABB Double Cone Burner (EV Burner)
Authors: Döbbeling K. , Knöpfel H. P. , Polifke W. , Winkler D. , Steinbach C. , Sattelmayer T.
Published: February 2015

A novel combustion technique, based on the Double Cone Burner, has been developed and tested. NOx emissions down to very low levels are reached without the usual strong dilution of the fuel for MBtu syngases from oxygen blown gasification of coal or residual oil. A limited amount of dilution is necessary in order to prevent ignition during the mixing of fuel and combustion air.

The relevant properties of the fuel are reviewed in relation to the goal of achieving premixed combustion. The basic considerations lead to a fuel injection strategy which is completely different from that for natural gas. A high speed premixing system is necessary due to the very short chemical reaction times of MBtu fuel. Fuel must be prevented from forming ignitable mixtures inside the burner for reliability reasons. A suitable fuel injection method, which can be easily added to the ABB double cone burner, is described. In common with the design of the standard EV burner, the MBtu EV burner with this fuel injection method is inherently safe against flashback.

Three dimensional flow field and combustion modelling is used to investigate the mixing patterns and the location of the reaction front. Two burner test facilities, one operating at ambient and the other at full gas turbine pressure, have been used for the evaluation of different burner designs. The full pressure tests were carried out with the original gas turbine burner size and geometry. Combing the presented numerical predictive capabilities and the experimental test facilities, burner performance can be reliably assessed for a wide range of MBtu and LBtu fuels (residue oil gasification, waste gasification, coal gasification etc.).

The atmospheric tests of the burner show NOx values below 2 ppm at an equivalence ratio equal to full load gas turbine operation. The NOx increase with pressure was found to be very high. Nevertheless, NOx levels of 25 vppmd (@ 15% O2) have been measured at full gas turbine pressure. Implemented into ABB’s recently introduced gas turbine GT13E2 the new combustion technique will allow a more straightforward IGCC plant configuration without air extraction from the gas turbine to be used.
New Machining Method for Nickel Based Thermal Sprays
Authors: Cohen Joel H. , Dailey James H.
Published: February 2015

The routine overhaul and repair of gas turbine components requires dimensional restoration of many components. This process is usually accomplished by using various thermal sprays to build up the worn part surface and then machining or grinding the thermal sprays to correct part tolerances and dimensions. These surfaces usually contain numerous holes that generate heavily interrupted surfaces to be machined. The combination of interrupted cuts and a very wear resistant thermal spray causes rapid tool wear on conventional carbide cutting tools. This rapid tool wear also produces poor surface finish, part taper, chipping around the hole edges, and increased tool pressure that could result in lifting or peeling of the sprayed material from the parent metal.

This paper summarizes the results of machining nickel based thermal sprays with polycrystalline cubic boron nitride (PCBN) cutting tools. The tests have shown a minimum 2–5x improvement in surface finish, dimensional control, part taper and up to 10x increase in productivity. The PCBN tools also generated lower cutting forces resulting in reduced stress and higher bond strengths in the part.

This paper presents the data collected and the recommended machining parameters developed under controlled conditions for machining air plasma sprayed Metco 443, Metco 450, Inconel 718, two wire arc applied TAFA 75B, TAFA 73MXC, and high velocity oxygen fuel applied Inconel 718.
Development of a Custom Ambient NOx Correction Equation for a Mars SoLoNOx Gas Turbine
Authors: Hung W. S. Y. , Fahme A. , Kubasco A.
Published: February 2015

The United States federal new source performance standards (NSPS) for stationary gas turbines contain NOx limits that are standardized based on the International Standards Organization (ISO) standard for ambient conditions. The measured NOx emissions from stationary gas turbines at test conditions are to be corrected to ISO standard ambient conditions using a recommended equation, which was developed using data from conventional (diffusion flame) combustion systems. It is genearlly expected that this correction equation will require a revision when advanced lean premixed or hybrid combustion system is utilized.

At the site of the first Mars 100S SoLoNOx gas turbine, a continuous emissions and gas turbine performance data gathering system has been installed. From the data gathered, the non-applicability of this NOx ambient correction equation is demonstrated. This points to the need to develop a custom NOx ambient correction equation for gas turbines with an advanced lean premixed system.

Using a proven NOx model, the humidity effect on NOx emissions from an advanced lean premixed system is determined to be much stronger than that for a conventional combustion system. The humidity effect was determined based on an engineering application of the NOx model. Through statistical analyses, this stronger humidity effect is supported by more than one thousand five hundred data points gathered over a eight-month period at the above customer’s site, covering an ambient temperature range over 100°F (56°C). Using this newly determined humidity effect and a least-square curve fit of the data, a custom NOx ambient correction equation has been developed for this prototype Mars SoLoNOx gas turbine.
The European Transonic Wind Tunnel: ETW High Quality Performance With High Productivity
Authors: Tizard J. A. , Bouis X.
Published: February 2015

The paper reviews the design for performance of this new high Reynolds number facility, which aims at achieving the two, sometimes conflicting, requirements of high testing quality as well as high productivity. As far as productivity is concerned, specific related features include the modular multiple model cart concept, the capability to work on cold models, the sequencing of model handling activities and the “fast” control of all wind tunnel and model handling operations. The plans for the future incorporation of a half model test rig and the possible use of turbine powered simulators in ETW are addressed.

An assessment of the anticipated productivity of the facility is presented. The self supporting nature of ETW GmbH is also taken into account. Over the initial operating phase, important commercial parameters such as nitrogen and energy consumption, staffing levels, occupancy etc. will be under close scrutiny, in order to optimize cost-effectiveness. Data from the early commissioning and calibration tests indicate that testing charges for ETW should remain at a level comparable to those for conventional wind tunnel testing, all things being equal.
Benefits of MS 6001B Gas Turbine in Cogeneration: The UEM Power Plant Case
Authors: Remy Pierre M. , Bolssenin Yves M. , Molière Michel M.
Published: February 2015

Long before the neologism “Cogeneration” was coined (around 1978), UEM’s Chambière Power Plant — which dates back to the turn of the century — was already supplying the city of Metz, east of France, with combined heat and power.

In 1992, Chambière experienced a major turning point in its history with the installation of a new unit based on one MS 6001B “Heavy Duty” gas turbine. This model, rated 38 MWe - ISO and burning natural gas or fuel oil has become the core of a new cogeneration unit exhibiting an outstanding performance:

- efficiency higher than 80% (LHV) providing a 20% energy saving in comparison to a conventional plant,

- low pollutant emissions (NOx, CO, HC) and low contribution to the greenhouse-effect (CO2).

The gas turbine has been equipped with two steam injection devices, for DeNOx and power augmentation respectively, resulting in a very flexible system.

After describing the power plant and giving its main achievements in the fields of energy and emissions, the paper briefly presents several improvements intended to protect both the turbine and the environment.
Forging of Compressor Blades: Temperature and Ram Velocity Effects
Authors: Zhen K. , Saigal A. , Chan T. S.
Published: February 2015

Forging is one of the most widely used manufacturing process for making high strength, structurally integrative, impact and creep resistant Ti-6A1-4V compressor blades for jet engines. In addition, in modern metal forming technology, finite element analysis method and computer modeling are being extensively employed for initial evaluation and optimization of various processes, including forging.

In this study, DEFORM, a rigid viscoplastic two-dimensional finite element code, was used to study the effects of initial die temperature and initial ram velocity on the forging process. For a given billet, die temperature and ram velocity influence the strain rate, temperature distribution, and thus the flow stress of the material. The die temperature and the ram velocity were varied over the range 300–700°F and 15–25 in/sec, respectively, to estimate the maximum forging load and the total energy required to forge compressor blades. The ram velocity was assumed to vary linearly as a function of stroke.

Based on the analysis, it was found that increasing the die temperature from 300–700°F decreases the forging loads by 19.9% and increases the average temperature of the workpiece by 43°F. Similarly, increasing the initial ram velocity from 15–25 in/sec decreases the forging loads by 25.2% and increases the average temperature of the workpiece by 36°F. The nodal temperature distribution is bimodal in each ease. The forging energy required to forge the blades is approximately 18 kips*in/in.
Development of the Trent Econopac
Authors: Myers Gerry A. , Jackson Anthony J. B.
Published: February 2015

Through an alliance established in 1992 between Westinghouse Electric Corporation and Rolls-Royce plc, a program has been implemented that will bring the industrial Trent aero engine to the power generation marketplace. The Rolls-Royce Trent has been initially sized at 50 MW, with a development potential to higher power ratings, and is offered by Westinghouse as a complete power generation package, the “Trent EconoPac”.

The Trent EconoPac sets a new performance standard in the industry with a nominal simple cycle efficiency of 42 percent. It is also ideal for combined cycle and cogeneration applications; a net combined cycle power of 63 MW at 52 percent efficiency can be developed. This paper describes the Trent industrial engine and EconoPac and reviews the development program with emphasis on unique features that benefit the power plant operator.
Advances in Abradable Coatings for Gas Turbines
Authors: Schmid R. , Nicoll A. R.
Published: February 2015

Gas turbine engine development continues to accelerate, creating more demanding requirements for abradable seal coatings. These coatings are necessary to provide very small clearances between the rotating and stationary parts in order to minimize gap losses and so Increase efficiency. The relatively few abradable coating materials developed over the last 20 years still perform well in many blade tip seal and labyrinth seal applications. However, rising operating temperatures, corrosion and other environmental changes, longer overhaul times and even better tip clearances are dictating the design of new coating materials which requires a strong scientific approach. For example, ways are being Investigated to replace Nickel-Graphite and other flame sprayed coatings being used between 450 and 700°C respectively because of steady state/corrosion/oxidation/erosion and wear problems respectively.

New plasma and HVOF sprayed coatings have been developed using a systematic approach based on material response to operating conditions, minimizing trial and error. The major steps in the programme were:

1. Selection of constituent materials able to withstand service temperatures up to 325 (AISI-Polyester or Polyimide), 450 (AISI base), 700 (MCrAlY base) and 1100°C (ceramic base) respectively.

2. Powder particle manufacture and coating deposition to guarantee highly reproducible coatings.

3. Coating optimization based on wear tests carried out using a fully instrumented abradability test rig and wear mechanism analysis.

4. An investigation of blade tipping systems for high temperature applications.

This paper discusses the results of plasma sprayed coatings developed for use at 450 and 700°C.
Gas Turbine Model With Intensive Cooling
Authors: Khodak Evgeni A. , Romakhova Gallna A.
Published: February 2015

A method of calculation of cooled gas turbine parameters is proposed. The method is based on the solution of the expansion process equation, heat transfer equations for cooled elements and on the results of the statistic processing of the parameters.

The method is valid for the turbine with any cooling system and gaseous heat carrier. Turbine output determination error does not exceed 0,5–1,0%.

The method allows to obtain the characteristics of gas turbines and gas turbine units (GTU) with open and closed air and steam cooling systems and to carry out an efficiency analysis of their performance in power generating units of various structure.
Multilevel Optimization Procedures for Gas Turbine Design: Part I — Mathematical Formulation
Authors: Ghiglino Fabio , Massardo Aristide
Published: February 2015

Two procedures for splitting a large optimization energy systems problem into a hierarchy of separated but coupled subproblems are introduced.

The mathematical formulations of the two multilevel optimization procedures are presented and discussed. Both the methods are based on a linear decomposition principle. In the first, the concept of optimal sensitivity is utilized, while in the second this concept is relaxed and the mathematical formulation is more simple.

The applicability of the analyzed procedures will be illustrated by formulation of realistic analysis and design problems in the field of gas turbine systems, in the second part of the present work (Ghiglino and Massardo, 1994).