bluuebunny/crossref_metadata_2025_split huggingface dataset:
Induced Draft Fan Innovation for Heat Recovery Steam Generators
Authors: Beasley O. W. , Hutchins E. C. , Predick P. R. , Vavrek J. M. 
Published: February 2015

A first of its kind, induced draft (ID) heat recovery steam generators (HRSG) have been in service at a cogeneration facility since 1991.
A preliminary engineering study considered a forced draft (FD) fan to supply combustion air to the HRSG duct burners (when the combustion turbine (CT) is out of service) as a traditional design; however, the study indicated that the FD fan may require the HRSG duct burner to be shut off following a CT trip and reignited after the FD fan was in service. Although the induced draft HRSG design cost more than the FD fan design, the induced draft design has improved the cogeneration facility’s steam generation reliability by enabling the HRSG to remain in service following a CT trip.
This paper briefly summarizes the preliminary engineering study that supported the decision to select the ID fan design. The paper also discusses the control system that operates the fresh-air louvers, duct burners, HRSG and ID fan during a CT trip. Startup and operating experiences are presented which demonstrate the effectiveness of the design. Lessons learned are also summarized for input into future induced draft HRSG designs.
Application of Computational Fluid Dynamics to Turbine Disc Cavities
Authors: Virr G. P. , Chew J. W. , Coupland J. 
Published: February 2015

A CFD code for the prediction of flow and heat transfer in rotating turbine disc cavities is described and its capabilities demonstrated through comparison with available experimental data. Application of the method to configurations typically found in aeroengine gas turbines is illustrated and discussed.
The code employs boundary-fitted coordinates and uses the k-ε turbulence model with alternative near-wall treatments. The wall function approach and a one-equation near-wall model are compared and it is shown that there are particular limitations in the use of wall functions at low rotational Reynolds number. Validation of the code includes comparison with earlier CFD calculations and measurements of heat transfer, disc moment and fluid velocities.
It is concluded that, for this application CFD is a valuable design tool capable of predicting the flow at engine operating conditions thereby offering the potential for reduced engine testing through enhanced understanding of the physical processes.
A Bypass Transition Model for Boundary Layers
Authors: Johnson Mark W. 
Published: February 2015

Experimental data for laminar boundary layers developing below a turbulent free stream shows that the fluctuation velocities within the boundary layer increase in amplitude until some critical level is reached which initiates transition. In the near wall region, a simple model, containing a single empirical parameter which depends only on the turbulence level and length scale, is derived to predict the development of the velocity fluctuations in laminar boundary layers with favourable, zero or adverse pressure gradients. A simple bypass transition model which considers the streamline distortion in the near wall region brought about by the velocity fluctuations suggests that transition will commence when the local turbulence level reaches approximately 23%. This value is consistent with experimental findings. This critical local turbulence level is used to derive a bypass transition prediction formula which compares reasonably with start of transition experimental data for a range of pressure gradients (λθ = −0.01 to 0.01) and turbulence levels (Tu = 0.2% to 5%).
Further improvement to the model is proposed through prediction of the boundary layer distortion, which occurs due to Reynolds stresses generated within the boundary layer at high free stream turbulence levels and also through inclusion of the effect of turbulent length scale as well as turbulence level.
Adaptive Unstructured 2D Navier-Stokes Solutions on Mixed Quadrilateral/Triangular Meshes
Authors: Connell Stuart D. , Holmes D. Graham , Braaten Mark E. 
Published: February 2015

This paper presents a solution adaptive scheme for solving the Navier-Stokes equations on an unstructured mixed grid of triangles and quadrilaterals. The solution procedure uses an explicit Runge-Kutta finite volume time marching scheme with an adaptive blend of second and fourth order smoothing. The governing equations are solved in a 2D, axisymmetric or quasi-3D form.
In viscous regions quadrilateral elements are used to facilitate the one dimensional refinement required for the efficient resolution of boundary layers and wakes. The effect of turbulence is incorporated through using either a Baldwin-Lomax or k-ε turbulence model.
Solutions are presented for several examples that illustrate the capability of the algorithm to predict viscous phenomena accurately. The examples are a transonic turbine, a nozzle and a combustor diffuser.
A New Approach to the Description of the Off-Design Losses in Radial-Inflow Turbine Rotors
Authors: Schölch M. 
Published: February 2015

The off-design behaviour of a radial-inflow turbine with pivotable nozzle vanes was measured. The turbine geometry is presented in figure 1. The losses produced in the rotor were determined over a wide range of operating conditions which were established by varying pressure ratio, speed of rotation of the rotor and the nozzle vane position.
Loss correlations proposed by other authors were used to approximate the measured losses. All correlations were only able to fit the results for a single nozzle position. None of the equations used gave a satisfactory approximation for all the operating points investigated. Therefore a new way of describing the rotor losses is presented and a physical explanation for the new correlation is given.
Experimental Determination of the Flow Field in the Tip Region of a LP-Steam Turbine
Authors: Zimmermann C. , Stetter H. 
Published: February 2015

Pneumatic multihole probes were applied to determine the local flow field in the tip region of a LP–steam turbine. For three tip clearances measurements were carried out varying the operating point of the turbine from full to partial load each.
The maxima of the tip clearance flow and the resulting jetflow in the adjacent axial–radial diffusor show a strong dependency on the operating point, the width of the tip gap, and the axial distance to the rotor. In contrast, the radial extension of the jetflow is primarily influenced by the operating point and limited to the upper 10% of the flow channel. The leakage flow rate and the interaction with the main flow are increasing when widening the tip clearance which leads to a significant global efficiency deficit. In order to prevent a smooth flow through the tip gap, the design is changed by casing treatment upstream of the running wheel yielding a positive overlap of the gap. Its effect on the flow is investigated and compared to the other configurations of the turbine.
Experimental and Numerical Study of the Time-Dependent Pressure Response of a Shock Wave Oscillating in a Nozzle
Authors: Ott P. , Bölcs A. , Fransson T. H. 
Published: February 2015

Investigations of flutter in transonic turbine cascades have shown that the movement of unsteady normal shocks has an important effect on the excitation of blades. In order to predict this phenomenon correctly, detailed studies concerning the response of unsteady blade pressures versus different parameters of an oscillating shock wave should be performed, if possible isolated from other flow effects in cascades. In the present investigation the correlation between an oscillating normal shock wave and the response of wall mounted time-dependent pressure transducers was studied experimentally in a nozzle with fluctuating back pressure. Excitation frequencies between 0 Hz and 180 Hz were investigated.
For the measurements, various measuring techniques were employed. The determination of the unsteady shock position was made by a line scan camera using the Schlieren flow visualization technique. This allowed the simultaneous use of unsteady pressure transducers to evaluate the behavior of the pressure under the moving shock.
A numerical code, based on the fully unsteady Euler equations in conservative form, was developed to simulate the behavior of the shock and the pressures.
The main results of this work were:
• The boundary layer over an unsteady pressure transducer has a quasi-steady behavior with respect to the phase lag. The pressure amplitude depends on the frequency of the back pressure.
• For the geometry investigated the shock amplitude decreased with increasing excitation frequency.
• The pressure transducer sensed the arriving shock before the shock had reached the position of the pressure transducer.
• The computed unsteady phenomena agree well with the results of the measurements.
Engineering Considerations of Gas Turbine/Waterjet Marine Propulsion Systems
Authors: Martin Paul , Blount Donald L. 
Published: February 2015

The installation of gas turbines in high-speed marine vessels is relatively new in the merchant marine sector. The main objective of this paper is to present the engineering considerations that were taken into account during the design, testing and classification of the propulsion machinery of DESTRIERO, a high-speed, aluminum hull craft. This Blue Ribbon record-holding vessel will be the basis for, the discussion which will highlight the value of a detailed technical assessment of a vessel’s propulsion system early in the design process.
The DESTRIERO is a 67.7 meter aluminum monohull designed to cross the Atlantic ocean without refueling at a speed in excess of 50 knots in a sea state 4. During trial runs the vessel exceeded 65 knots. In August 1992 during its eastbound transit, the vessel earned the current non-stop Atlantic crossing speed record of 53.09 knots. The propulsion system is provided by three General Electric (GE) LM1600 gas turbines, each developing 20,740 IGHP (ISO base rating). The gas turbines drive three KaMeWa waterjets through a Renk Tacke reduction gearbox. Reverse thrust and steering are accomplished through the two outer jets. Each turbine and its auxiliaries are packaged in MTU modules, which are flexibly mounted to the ship’s structure.
Advanced Ceramic Technology Developed for Industrial 300kW CGT (Ceramic Gas Turbine) Research and Development Project in Japan
Authors: Shimada Kazuaki , Ushijima Hiroyasu , Yabe Akira , Ogiyama Hisao , Tsutsui Yasukata 
Published: February 2015

The characteristics and the points of innovation for the ceramic technology established in the Japanese national energy conservation project supported by Agency of Industrial Science and Technology (AIST) MITI, entitled “The 300kW Industrial Ceramic Gas Turbine Research and Development Project” have been cleared and reviewed. Especially, from the viewpoint of the role and the characteristics of the ceramic components, the progress of the three types of the ceramic gas turbines, which are: (a) “Regenerative Single–shaft Ceramic Gas Turbine for Cogeneration” (CGT–301); (b) “Regenerative Two–shaft Ceramic Gas Turbine for Cogeneration” (CGT–302) and (c) “Regenerative Two–shaft Ceramic Gas Turbine for Mobile Power Generation” (CGT–303), has been explained in parallel.
All ceramic components have already been manufactured for the turbine inlet temperature of 1200 deg C and tested as the components, which will be assembled and evaluated as the interim evaluation test in 1993. Especially, the characteristics of the ceramic components have been reviewed in several points such as the fabrication process for clearing the contrast among three types of ceramic gas turbine.
Optimization of Gas Turbine Engine Elements by Probability Criteria
Authors: Egorov I. N. , Kretinin G. V. 
Published: February 2015

Procedure for the stochastic optimization of design parameters of gas turbine engine components for a prescribed level of production technology is discussed. Such combined criteria of the stochastic optimization as effectiveness-probability of realizing a design of an intricate technical object are proposed.
With reference to the task of optimum designing the rows of a multistage axial flow compressor, there are presented the results, obtained for various probability criteria, in parallel with conducting their comparative analysis, and there are also investigated optimum stable (robust) characteristics of designs obtained for various levels of technology. There are also demonstrated a possibility of a significant increase in probability to realize in actual practice the design, obtained in stochastic setting, as compared to the design, obtained in deterministic setting.
Present Status of Standardization for Fine Ceramics in Japan
Authors: Matsuhiro Keiji , Matsui Minoru 
Published: February 2015

The commercialization of ceramic components for structural applications are continuing gradually, but not as quickly as expected. One of the obvious reasons is that a worldwide, common set of standard methods to compare and assure the ceramic component quality does not exist.
In order to solve this problem, Japan has set up cooperative activities industrial standards for the structural ceramics among the government, academia and industry. As of 1992, 16 methods of the standard testing procedure had been settled.
However, further work is needed, as at least another 203 standards are required. The following topics will be reviewed.
1. The relevant organizations, their task functions, and how they are co-working with each other.
2. Schedule of standardization settlement.
3. General steps involved in finishing a standard test method.
4. Present view on utilizing properties measured by standard methods of Japanese industry.
5. Future tasks to be solved.
Effects of Embedded Vortices on Injectant From Film Cooling Holes With Large Spanwise Spacing and Compound Angle Orientations in a Turbulent Boundary Layer
Authors: Ligrani Phillip M. , Mitchell Stephen W. 
Published: February 2015

Experimental results are presented which describe the effects of embedded, longitudinal vortices on heat transfer and film injectant downstream of a single row of film cooling holes with compound angle orientations. Holes are spaced 7.8 hole diameters apart in the spanwise direction so that information is obtained on the interactions between the vortices and the injectant from a single hole. The compound angle holes are oriented so that their angles with respect to the test surface are 30 degrees in a spanwise/normal plane projection, and 35 degrees in a streamwise/normal plane projection. A blowing ratio of 0.5 is employed and the ratio of vortex core diameter to hole diameter is 1.6–1.67 just downstream of the injection holes (x/d=10.2). At the same location, vortex circulation magnitudes range from 0.15 m2/s to 0.18 m2/s.
The most important conclusion is that local heat transfer and injectant distributions are strongly affected by the longitudinal embedded vortices, including their directions of rotation and their spanwise positions with respect to film injection holes. To obtain information on the latter, clockwise rotating vortices R0-R4 and counter-clockwise rotating vortices L0-L4 are placed at different spanwise locations with respect to the central injection hole located on the spanwise centerline. With vortices R0-R4, the greatest disruption to the film is produced by the vortex whose downwash passes over the central hole (R0). With vortices L0-L4, the greatest disruption is produced by the vortices whose cores pass over the central hole (L1 and L2). To minimize such disruptions, vortex centers must pass at least 1.5 vortex core diameters away from an injection hole on the upwash sides of the vortices and 2.9 vortex core diameters away on the downwash sides of the vortices. Differences resulting from vortex rotation are due to secondary flow vectors, especially beneath vortex cores, which are in different directions with respect to the spanwise velocity components of injectant after it exits the holes. When secondary flow vectors near the wail are in the same direction as the spanwise components of the injectant velocity (vortices R0-R4), the film injectant is more readily swept beneath vortex cores and into vortex upwash regions than for the opposite situation in which near-wall secondary flow vectors are opposite to the spanwise components of the injectant velocity (vortices L0-L4). Consequently, higher Stanton numbers are generally present over larger portions of the test surface with vortices R0-R4 than with vortices L0-L4.
The Selection Process and Comparative Air Filter Performance Testing for Combustion Turbine Inlet Air Filters
Authors: Gidley Dave , Fritz Frederick M. , Yu Henry H. S. 
Published: February 2015

Designers, OEM’s and Users have available to them a variety of standard air filter performance tests that can be used and currently are being used to specify inlet air filters for combustion turbines. These standard tests for the most part have been developed for the heating, ventilating and air conditioning industry using developed synthetic dust that simulates an air composition comprised of mostly recirculated air blended with outdoor make-up air. Other available standard tests and standard test dusts have been developed for diesel and gasoline powered engines. To our knowledge no standard air filter test method has been developed for filters to be used on combustion turbine air intakes using typical outdoor air. In our opinion, a standard test relating to 100% outdoor air, pressure drop rise over time, particle size and the particle size distribution most commonly recorded at combustion turbine installation sites would be beneficial in specifying and selecting the “best” filter for todays’ combustion turbine applications.
This paper will review and compare the various air filter tests currently used for combustion turbine inlet filtration selection and recommend an all-inclusive test standard that could be used in the future.
Predicting the Ultimate Performance of Advanced Power Cycles Based on Very High Temperature Gas Turbine Engines
Authors: Chiesa Paolo , Consonni Stefano , Lozza Giovanni , Macchi Ennio 
Published: February 2015

It is well known that the history of gas turbine engines has been characterized by a very clear trend toward higher and higher operating temperatures, a growth which in the past 40 years has progressed at the impressive pace of approximately 13°C/year. Expected improvements in blade cooling techniques and advancements in materials indicate that this tendency is going to last for long time, leading to firing temperatures of over 1500°C within the next two decades.
This paper investigates the impact of such temperature increase on optimal cycle arrangements and on ultimate performance improvements achievable by future advanced gas/steam cycles for large-scale power generation.
Performance predictions have been carried out by a modified, improved version of a computer code originally devised and calibrated for “1990 state-of-the-art” gas/steam cycles. The range of performances to be expected in the next decades has been delimited by considering various scenarios of cooling technology and materials, including the extreme situations of adiabatic expansion and stoichiometric combustion.
The results of parametric thermodynamic analyses of several cycle configurations are presented for a number of technological scenarios, including cycles with intercooling and reheat. A specific section discusses how the optimum configuration of the bottoming steam cycle changes to keep up with exhaust gas temperature increases.
Calculations show that, under plausible assumptions on future technology advancements, within two decades the proper selection of plant configuration and operating parameters can yield net efficiencies of over 60%.
Large Combined Cycle HRSG Units Impact of Operating Considerations
Authors: Davis James S. , Steffen Mark , Thompson Anthony T. 
Published: February 2015

Combustion turbine combined cycle plants continue to increase their role in worldwide power generation. Advanced combined cycle plants provide:
• high efficiency, often in excess of 50%
• short project schedules
• reasonable cost with minimum environmental considerations
For reliable operation of these facilities, it is essential the Heat Recovery Steam Generator (HRSG) design adequately address issues to include:
• required load rangeability
• transient operation, particularly start-up and shutdown
• low life cycle costs through high availability
This paper will address the more detailed aspects of the design configuration of large HRSG units.
Impeller Rotating Stall as a Trigger for the Transition From Mild to Deep Surge in a Subsonic Centrifugal Compressor
Authors: Ribi Beat , Gyarmathy Georg 
Published: February 2015

The present paper concerns the transition from mild to deep surge in a single stage centrifugal compressor using a vaned diffuser. Time-resolved measurements of the mass flow rate and the static pressures at various locations of the compressor were analyzed for different diffuser geometries and different operating points in the compressor map.
When the throttle valve was gradually closed at an impeller tip Mach number (Mu) above 0.4, the compressor showed first mild and then deep surge whereas at Mu=0.4 rotating stall was the dominant instability. This single-cell rotating stall was identified to be caused by the impeller.
During mild surge at higher Mach numbers the instantaneous flow and pressure traces showed that the overall flow at the stage inlet intermittently dropped below the critical value associated with the occurence of impeller rotating stall. Rotating stall appeared for a while but vanished as soon as the flow increased again. With further throttling, however, a threshold was reached at which rotating stall triggered deep surge. The results show that triggering only occurred if the flow deficiency causing rotating stall persisted long enough to permit the stall cell to make at least one or two revolutions.
Highly Loaded Tandem Compressor Cascade With Variable Camber and Stagger
Authors: Sachmann Johann , Fottner Leonhard 
Published: February 2015

Highly loaded compressors, resulting from high pressure ratios and as few compressor stages as possible, need not only stators with variable stagger but furthermore with variable camber. By this means the blading can be adapted to the velocity triangles at off-design engine power setting leading to less sacrifice of the cycle efficiency and thus better engine power and improved fuel consumption.
Stators with variable stagger and camber can be accomplished by a tandem stator design where both stator blades can be adjusted independently from each other. In this investigation the usable range of such a tandem arrangement is measured and it is shown how the interference between the two blades can decrease losses in comparison with the two single blades of the tandem arrangement. Furthermore an inviscid flow calculation with a 2D-Euler-code shows the influence of this interference on the whole flow field.
Computational Structural Reliability Analysis of a Turbine Blade
Authors: Millwater H. R. , Wu Y.-T. 
Published: February 2015

A system reliability methodology has recently been developed to determine accurately and efficiently the reliability of structures with multiple failure modes. This paper explores the computational implementation and application of the methodology through the structural system reliability calculation of a turbine blade subject to randomness in material properties. Failure due to creep, stress overload, and vibration is considered.
The methodology consists of a probabilistic system reliability analysis methodology integrated with finite element methods. The failure paths and failure modes are organized using a fault tree. An efficient method for assessing the reliability of a single failure mode, i.e., component reliability, is implemented as well as an efficient adaptive importance sampling method to assess the system reliability. A probabilistic structural analysis program, NESSUS, is used for the calculations.