bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow Analysis in a Transonic Centrifugal Compressor Rotor Using 3-Component Laser Velocimetry
Authors: Krain H. , Karpinski G. , Beversdorff M. 
Published: July 2014

The paper describes the flow conditions found inside an optimized transonic, high pressure ratio centrifugal compressor rotor operated with a rotor tip speed of 586 m/s. The rotor was coupled with a vaned diffuser of rather small exit radius ratio. Measurements and calculations were carried out on this device. A newly developed 3-component hybrid Laser velocimeter was applied for the optical measurements inside the rotating system. For the first time the new measurement technique delivered three velocity components instead of only two for such a compact machine with very narrow flow channels. An available 3D calculation system with an embedded Navier-Stokes solver was used for the theoretical approach.
The flow field development is described with the help of optical measurement results taken at measurement planes located at the rotor inlet and exit as well as at 40% and 60% flow path length. The measured 3D effects were highest in the middle of the flow channel, where the flow is turned from axial to radial. Here the curvature effects in the meridional plane and the enhancement of secondary flow are significant. The agreement between the theoretically and experimentally obtained third velocity component is quite good, especially in the area with strong secondary flows.
Compressor Performance With Water Injection
Authors: Horlock J. H. 
Published: July 2014

There has been renewed interest recently in the injection of water at inlet to gas turbine plants. As is to be expected there is a drop in temperature at the inlet face to the compressor and this obviously has an effect on compressor performance. But a second effect occurs within the early stages of the compressor itself, associated with an increase in the effective specific heat due to continuing evaporation of the water droplets. Consequently there are movements away from design operating conditions on the stage characteristics.
A one-dimensional analysis of compressor off-design performance is developed to illustrate these effects, which appear to be appreciable, even for very small quantities of water injection.
3D Transonic Flow in a Compressor Cascade With Shock-Induced Corner Stall
Authors: Weber Anton , Schreiber Heinz-Adolf , Fuchs Reinhold , Steinert Wolfgang 
Published: July 2014

An experimental and numerical study of the transonic flow through a linear compressor cascade with endwalls was conducted. The cascade with a low aspect ratio of 1.34 was tested at an inlet Mach number of 1.09 and a Reynolds number of 1.9×106. Detailed flow visualizations on the surfaces and 5-hole probe measurements inside the blading and in the wake region showed clearly a 3-dimensional boundary layer separation on the blade surface and the sidewall, and a severe corner stall induced by a strong 3D shock system at blade passage entrance.
The experimental data has been used to validate and improve the 3D Navier-Stokes code TRACE. Results showed an excellent resolution of the complex flow field. Surface pressure distributions on the entire blade surface and the endwalls, flow angle and total pressure contours within the blade passage and the wake are compared with the experimental results. An analysis of the secondary flow of this highly staggered cascade did not show the classical corner vortex. Instead, a severe flow deviation and partly reverse flow near the walls is seen. The flow solver helped to identify a weak ring vortex that originates from the passage sidewall. Surface oil flow pictures on the blade contour and the sidewall are in qualitatively good agreement to numerical surface streaklines. A considerable improvement of the numerical results could be achieved by a gradual grid refinement especially in the corner region and by successive code development.
Automised Calibration of Empirical Loss- and Deviation Models for Compressor Blade Rows
Authors: Hansen Andreas , Kappis Wolfgang 
Published: July 2014

Within a project of German research co-operation AG Turbo, the operational behaviour of a 15-stage transonic compressor rig was experimentally and numerically investigated. The rig is geometrically scaled from an existing advanced heavy-duty gas turbine compressor with CDA-blading.
The development and validation of a process for automatic calibration of empirical loss and deviation correlations implemented in a compressor map calculation program for multistage axial compressors (mean section performance calculation), based on existing compressor map measurement data is the target of this project.
In Order to calibrate the empirical loss- and deviation models 1D-data as overall pressure ratio, mass flow and polytropic efficiency was extracted from the measurement data.
Subsequently the coupling of an optimisation algorithm, the compressor map calculation program and the extracted measurement data had to be realised for the automised process of calibration as the second step.
Due to different targets for the parameterised loss- and deviation models they were adjusted separately with different objectives as mass flow for the deviation model and as efficiency for the loss model. Following the cumulative calibration was carried out with a combined target of mass flow and efficiency deviations.
The process for the automatic calibration of the empirical loss and deviation correlations implemented in a compressor map calculation program has been successfully developed and validated for different speed lines based on the measurement data of a 15-stage compressor rig.
Compressor Characteristics in Gas Turbine Performance Modelling
Authors: Jones Geoff , Pilidis Pericles , Curnock Barry 
Published: July 2014

The choice of how to represent the performance of the fans and compressors of a gas turbine engine in a whole-engine performance model can be critical to the number of iterations required by the solver or indeed whether the system can be solved.
This paper therefore investigates a number of compressor modelling methods and compares their relative merits. Particular attention is given to investigating the ability of the various representations to model the performance far from design point. It is noted that, for low rotational speeds and flows, matching on pressure ratio will produce problems, and that efficiency is a discontinuous function at these conditions. Thus, such traditional representations of compressors are not suitable for investigations of starting or windmilling performance.
Matching on pressure ratio, Beta, the Crainic exit flow function and the true exit flow function is investigated. The independent parameters of isentropic efficiency, pressure loss, a modified pressure loss parameter, specific torque, and ideal and actual enthalpy rises are compared.
The requirements of the characteristic choice are investigated, with regard to choosing matching variables and ensuring that relationships are smooth and continuous throughout the operating range of the engine.
Convective Blade Cooling Modelling for the Analysis of Innovative Gas Turbine Cycles
Authors: Jordal Kristin , Torbidoni Leonardo , Massardo Aristide F. 
Published: July 2014

With the objective to perform reliable gas-turbine cycle calculations, a new, simultaneous use of two different thermodynamic blade cooling evaluation codes is presented. The proposed approach can be used to evaluate: (i) the blade coolant mass flow rate; (ii) the blade internal geometry data, necessary for the evaluation of (iii) the pressure drop of the coolant that flows through the blade; (iv) the main flow (hot gas side) Stanton number (employed to get concordance between input data for the two models), and (v) the temperature of the coolant as it leaves the blade at the outlet section Tco. The results for the cooled blade can easily be employed on a system level.
The base of the study is available data for air-cooled conventional gas turbine blades. Thereafter, for a given blade geometry, it is possible to investigate the influence of changing fluid properties for both coolant and hot gas, which is useful for studies of innovative gas turbine cycles.
Options to Maximize Power Output for Merchant Plants in Combined Cycle Applications
Authors: Tawney Rattan , Pearson Cheryl , Brown Mona 
Published: July 2014

Deregulation and growth in the power industry are causing dramatic changes in power production and distribution. The demand for peak power and potentially high revenues due to premium electricity rates has attracted independent developers to the concept of Merchant Power Plants (MPPs).
Over 100,000 MW of greenfield capacity is currently being developed through approximately 200 merchant plants in North America. These MPPs will have no captive customers or long-term power purchase agreements, but will rely on selling electricity into a volatile electricity spot market. Because of this, MPPs need the capability to export as much power as possible on demand. MPPs must also have the capability to produce significant assets in order to compete in the marketplace, based on both technical and commercial operation factors such as value engineering, life-cycle cost management, and information technology. It is no surprise then, that almost all merchant project developers have specified combined cycle (CC) technology. The CC power plant offers the highest thermal efficiency of all electric generating systems commercially available today. It also exhibits low capital costs, low emissions, fuel and operating flexibility, low operation and maintenance costs, short installation schedule, and high reliability/availability.
However, since gas turbines (GTs) are the basis for CC power plants, these plants experience power output reductions in the range of 10 to 15 percent during summer months, the period most associated with peak power demand. In order to regain this loss of output as well as to provide additional power to meet peak demands, the most common options are GT inlet fogging, GT steam injection, and heat recovery steam generator (HRSG) supplemental firing. This paper focuses on plant design, cycle performance, and the economics of plant configuration associated with these options. Guidelines are presented in this paper to assist the owner in selecting power enhancement options for the MPP that will maximize their Return on Equity (ROE).
Qualification of a Frequency Scanning Eddy Current Equipment for Nondestructive Characterization of New and Serviced High-Temperature Coatings
Authors: Antonelli Giampiero , Crisafulli Paola , Tirone Giacomo 
Published: July 2014

As modern gas turbines are continuously being upgraded, mainly through the increase of their firing temperature and cooling optimization, the prime protection of the high technology and high-cost hot gas path parts is increasingly being transferred to the coatings. In order to avoid the risk of structural damage of these components, with its potential for greater economic losses — mostly traceable to unexpected prime time outages — refurbishment cycle should be dictated by the amount of the life actually expended by the coating.
To address the issues of quality and condition assessment of new and serviced high-temperature coatings applied on buckets and vanes, an innovative non-destructive system was developed based on a frequency scanning eddy current technique. It combines outstanding high frequency hardware with model based analysis of raw data.
In the paper, quantitative data on equipment qualification are presented, relating to its capability in measuring both the thickness and β-aluminide depletion of MCrAlY coatings applied on Ni-base superalloys. The results of an inspection campaign on serviced blades, performed during major overhauls of ENEL gas turbines, will also be reported, together with recent system upgrades, aiming at extending its applicability to newer coatings such as thermal barriers and over-aluminized MCrAlY’s.
Pressure Surface Separations in Low Pressure Turbines: Part 1 of 2 — Midspan Behaviour
Authors: Brear Michael J. , Hodson Howard P. , Harvey Neil W. 
Published: July 2014

This paper describes an investigation into the behaviour of the pressure surface separation at midspan in a linear cascade. It is found that the pressure surface separation can be a significant contributor to the profile loss of a thin, solid, low pressure turbine blade that is typical of current engine designs.
Numerical predictions are first used to study the inviscid behaviour of the blade. These show a strong incidence dependence around the leading edge of the profile. Experiments then show clearly that all characteristics of the pressure surface separation are controlled primarily by the incidence. It is also shown that the effects of wake passing, freestream turbulence and Reynolds number are of secondary importance.
A simple two-part model of the pressure surface flow is then proposed. This model suggests that the pressure surface separation is highly dissipative through the action of its strong turbulent shear. As the incidence is reduced, the increasing blockage of the pressure surface separation then raises the velocity in the separated shear layer to levels at which the separation can create significant loss.
A Turbine Airfoil Aerodynamic Design Process
Authors: Xu C. , Amano R. S. 
Published: July 2014

A turbine airfoil aerodynamic design process, similar to the current industry practice, is used to design turbine airfoil sections. The airfoil generator code employs Bezier polynomial curves to produce smooth airfoil shapes.
For the calculations of the airfoil pressure distributions a discrete vortex method is used after the airfoil is designed and the novel Navier-Stokes (N-S) solver is developed for further examination of the airfoil performance. The vortex method can provide a fast way to calculate the airfoil pressure distributions. The N-S code is used to obtain the blade-to-blade quasi-three-dimensional, turbulent, and viscous flow characteristics. The time-dependent N-S equations are discretized and integrated in a coupled manner based on a finite-volume formulation as well as a flux-difference splitting. The flux-difference splitting method enables us to compute with a rapid convergence.
After the flow solver is validated with experimental data, this new code is further used to obtain an optimal airfoil design by analyzing the cascade flows. The present N-S code can handle computations of both subsonic and supersonic flows and can be connected to an external optimizer code with the airfoil generator.
Integrated Vehicle Comparison of Turbo-Ramjet Engine and Pulsed Detonation Engine (PDE)
Authors: Kaemming Tom 
Published: July 2014

The Pulsed Detonation Engine, PDE, is a unique propulsion system that uses the pressure rise associated with detonations to efficiently provide thrust. A study was conducted under the direction of the NASA Langley Research Center to identify the flight applications that provide the greatest potential benefits when incorporating a PDE propulsion system. The study was conducted in three phases. The first two phases progressively screened a large matrix of possible applications down to three applications for a more in-depth, advanced design analysis. The three applications best suited to the PDE were: 1) a supersonic tactical aircraft, 2) a supersonic strike missile and 3) a hypersonic single-stage-to-orbit, SSTO, vehicle. The supersonic tactical aircraft is the focus of this paper.
The supersonic, tactical aircraft is envisioned as a Mach 3.5 high altitude reconnaissance aircraft with possible strike capability. The high speed was selected based on the perceived high speed fuel efficiency benefits of the PDE. Relative to a turbo-ramjet powered vehicle, the study identified an 11% to 21% takeoff gross weight, TOGW, benefit to the PDE on the baseline 700 n.mi. radius mission depending on the assumptions used for PDE performance and mission requirements. The TOGW benefits predicted were a result of the PDE lower cruise specific fuel consumption, SFC, and lower vehicle supersonic drag. The lower vehicle drag resulted from better aft vehicle shaping, which was a result of better distribution of the PDE cross-sectional area.
The reduction in TOGW and fuel usage produced an estimated 4% reduction in life cycle cost for the PDE vehicle. The study also showed that the simplicity of the PDE enables concurrent engineering development of the vehicle and engine.
Development of a Temporally Modulated Fuel Injector With Controlled Spray Dynamics
Authors: Chang Hyeonsoo , Sipperley Chad , Nelson David , Edwards Chris 
Published: July 2014

It is now well established that combustion instability in liquid-fueled gas turbines can be controlled through the use of active fuel modulation. What is less clear is the mechanism by which this is achieved. This results from the fact that in most fuel modulation strategies not only is the instantaneous mass flow rate of fuel affected but so to are the parameters which define the post-atomization spray that takes part in the combustion. Specifically, experience with piezoelectric modulated sprays has shown that drop size, velocity, cone angle, and patternation are all affected by the modulation process. This inability to decouple changes in the fueling rate from changes in the spray distribution makes understanding of the mechanism of instability control problematic.
This paper presents the results of an effort to develop an injector which can provide temporal modulation of the fuel flow rate but without concomitant changes in spray dynamics. This is achieved using an atomization strategy which is insensitive to both fuel flow rate and combustor acoustics (an over-pressured spill-return nozzle) coupled with an actuator with flat frequency response (a low-mass voice coil). The design and development of the actuator (and its control system) are described, and a combination of Phase-Doppler Interferometry and imaging are used to establish its performance. Results show that the system is capable of producing sprays which have little variation in cone angle or spray distribution function despite variations in mass flow rate (number density) of greater than 50% over a range of frequencies of interest for control of combustion instability (10 Hz to 1 kHz).
The Model Steam Turbine: A Method of Evaluating a Heat Recovery Steam Generator in a Combined Cycle Plant
Authors: Schmidt Dietmar , Sullivan Terrence 
Published: July 2014

Turnkey and thermal island supply scopes present turbine manufacturers with a perfect way to sell their rotating products. The popularity of these plant configurations, along with the recent availability of more holistic test codes, has led to the need for an accurate and reasonable method of determining the thermal performance of the externally-purchased HRSG component.
To assess a multiple pressure HRSG, it is advantageous and convenient to have one single criterion for the evaluation of performance, especially when this criterion provides for the compensation of the different outlet energy streams. The so-called Model Steam Turbine method of HRSG evaluation was developed for these reasons. The result of the calculation, a lone performance criterion, is the shaft power of the fictitious Model Steam Turbine.
In this paper we will detail the components of the Model Steam Turbine calculation and explore the merits of this method. Some thoughts on performance corrections are also presented.
Contact Stresses in Dovetail Attachments: Alleviation via Precision Crowning
Authors: Sinclair G. B. , Cormier N. G. 
Published: July 2014

Previous studies of contact stresses in dovetail attachments provide verified finite element stresses as well as some simple physical models of such stresses. Generally there is good agreement between the finite element analysis and the simple physical models. Together the two identify a pinching mechanism as leading to large fluctuations in hoop stresses at the edges of contact. These fluctuating hoop stresses can be expected to be a major contributor to the fatigue of dovetail attachments.
The present study investigates a method of alleviating the fluctuating hoop stresses. This method entails crowning of the contacting flat on a blade. Such crowning is in two orthogonal directions on the blade flat. Two-dimensional finite element analyses are made in both directions. These analyses indicate that significant reductions in fluctuating hoop stresses can be achieved by the method, provided the crowning is controlled sufficiently precisely.
Semi-Closed Gas Turbine Cycles: An Ecological Solution
Authors: Laganelli A. L. , Rodgers C. , Lear W. E. , Meitner P. L. 
Published: July 2014

The impact on global warming of transportation and the infrastructure that supports it has been investigated over several decades. Anthropogenic heat and the generation of greenhouse gases from burning of fossil fuels and are major contributors to the warming process. An approach to mitigate these effects is discussed that considers semi-closed cycle gas turbine engines as a practical approach to slowing the release of greenhouse gases. Semi-closed cycle gas turbine engines have an inherent capability to reduce all regulated emissions while maintaining high efficiency, which in turn reduces CO2 emissions.
With emerging technology development that includes higher component efficiencies, high temperature material development, improved control devices, and advanced combustor designs, aided by computational fluid dynamics, semi-closed cycle engines appear to have the potential to mitigate global warming with little economic or infrastructural impact. A specific semi-closed engine type is described, the high pressure recuperated turbine engine (HPRTE), along with the inherent mechanisms for control of NOx, CO, unburned hydrocarbons, and particulates. Results from a breadboard demonstration of the HPRTE are discussed, as well as emerging technologies which benefit this type of engine.
Development of the Advanced Closed-Cycle Gas Turbine System
Authors: Koyama Miki , Mimaki Toshio 
Published: July 2014

This aims to put the fruits of the R&D; “The Hydrogen Combustion Turbine” in WE-NET Phase I Program(1993-1998) to practical use at an early stage. The topping regenerating cycle was selected as the optimum cycle, with energy efficiency expected to be more than 60%(HHV) under the conditions of the turbine inlet temperature of 1973K(1700°C) and the pressure of 4.8MPa,in it.
• As the turbine inlet temperature and pressure increase, issues to be resolved include the amount of NOx emissions and the durability of super alloys for turbine blades under such thermal conditions. In this respect, the development of the highly efficient methane-oxygen combustion technology, the turbine blade cooling technology, and the ultrahigh-temperature materials including thermal barrier coatings is being carried out.
• In 1999, the results made it clear that there are little error among the three analytic programs used to verify the system efficiency, it was verified that the burning rate was going to arrive at over 98% from the methane-oxygen combustion test (under the atmospheric pressure). And the type of vane “Film cooling plus recycle type with internal cooling system” was selected as the most suitable vane.