bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance Assessment of Semi-Closed Chemically Recuperated Gas Turbine Systems
Authors: Cau Giorgio , Cocco Daniele 
Published: August 2014

The paper is concerned with thermochemical recuperation in semi-closed gas turbine systems. Semi-closed turbines use CO2 as the main working fluid and the combustion process takes place with pure oxygen, allowing the CO2 produced to be easily removed. On the other hand, the exhaust heat recovery through thermochemical recuperation offers interesting capabilities in terms of high conversion efficiency and low polluting emissions.
System analysis and performance evaluation of the semi-closed, chemically recuperated gas turbine systems has been conducted and their performance assessed. A comparative analysis of semi-closed and open gas turbine cycles, with and without thermochemical recuperation, has been also carried out.
The results of the analysis show that thermochemical recuperation in semi-closed gas turbine systems can allow to remove the CO2 with high cycle efficiency and specific power.
Estimation of the Operating Characteristics of the Adjustable Speed Gas Turbine Power Generation System During Partial Load Operation
Authors: Nagafuchi Naoyuki , Kobayashi Nariyoshi , Utamura Motoaki 
Published: August 2014

This paper proposes an application of the simple cycle adjustable speed gas turbine power generation system for use as an independent power producer combined with a heavy duty gas turbine (output power 25MW, turbine inlet temperature 1400K class) having adjustable speed generators. Comparison results for a method to improve the thermal efficiency of this system using low NOx combustors are obtained.
The results of a performance study of the static characteristics for the system using forced IGV (Inlet Guide Vane) opening control during partial load adjustable speed operation, show an effect on thermal efficiency improvement. Comparison of the dynamic characteristics for the system using existing controllers and the system using the proposed controllers shows, the latter is able to restrain fluctuation of the fuel to air mass ratio during a transient changing the target rotational speed, under restricted operating conditions.
The Influence of the Boundary Layer State and Reynolds Number on Film Cooling and Heat Transfer on a Cooled Nozzle Guide Vane
Authors: Reiss Hans , Bölcs Albin 
Published: August 2014

Film cooling and heat transfer measurements were carried out on a cooled nozzle guide vane in a linear cascade, using a transient liquid crystal technique. Three flow conditions were realized: the nominal operating condition of the vane with an exit Reynolds number of 1.47e6, as well as two lower flow conditions: Re2L = 1.0e6 and 7.5e5. The vane model was equipped with a single row of inclined round film cooling holes with compound angle orientation on the suction side. Blowing ratios ranging form 0.3 to 1.5 were covered, all using foreign gas injection (CO2) yielding an engine-representative density ratio of 1.6. Two distinct states of the incoming boundary layer onto the injection station were compared, an undisturbed laminar boundary layer as it forms naturally on the suction side, and a fully turbulent boundary layer which was triggered with a trip wire upstream of injection.
The aerodynamic flow field is characterized in terms of profile Mach number distribution, and the associated heat transfer coefficients around the uncooled airfoil are presented. Both detailed and spanwise averaged results of film cooling effectiveness and heat transfer coefficients are shown on the suction side, which indicate considerable influence of the state of the incoming boundary layer on the performance of a film cooling row. The influence of the mainstream flow condition on the film cooling behavior at constant blowing ratio is discussed for three chosen injection regimes.
Experimental Investigation on Impingement Heat Transfer From Rib Roughened Surface Within Arrays of Circular Jets: Correlation
Authors: Chang Haiping , Zhang Jingyu , Huang Taiping 
Published: August 2014

Impingement heat transfer is one of the useful cooling methods for high temperature gas turbine blades and/or guide vanes in aeroengines. After the cooling jet impinges on the leading edge of the turbine blade and/or guide vane, it flows downstream and turns to be the initial crossflow for the aft row of impinging jet. The process of impingement heat transfer is quite complicated, especially when the target surface is rib roughened.
In this paper, the correlation of the impingement heat transfer characteristics has been analyzed based on thousands of experimental data in different parameter matching conditions (Ref = 7000∼20000, Gc/Gj = 0∼0.5, Xn = 5∼15, Zn = 1.5∼5, p/e = 5∼12 and e/d = 0.5∼1.5). The impingement heat transfer characteristics can be generally expressed as a functional formulation with the exponential functions of Ref, Zn, Xn, e/d and p/e, and a polynomial function of Gc/Gj. The interaction among the parameters are reflected in the exponents i, j, k, n, etc. and the weighing coefficients. By the regression processing to the experimental data, the exponents and the weighing coefficients are determined. The correlation equation of impingement heat transfer characteristics to the parameters has been finally concluded. Comparison shows that the correlation results are in good agreement with the experimental data.
Influence of Injection Type and Feed Arrangement on Flow and Heat Transfer in an Injection Slot
Authors: Cho Hyung Hee , Ham Jin Ki 
Published: August 2014

An experimental investigation is conducted to improve a slot film cooling system used for the cooling of a gas turbine combustor liner. The tangential slots are constructed of discrete holes with different injection types which are the parallel, vertical and combined to the slot lip. The investigation is focused on the coolant supply systems of normal-, inline-, and counter-flow paths to the mainstream flow direction. A naphthalene sublimation technique has been employed to measure the local heat/mass transfer coefficients in a slot wall with various injection types and coolant feeding directions. A numerical simulation is also conducted to help understand the flow patterns inside the slot for different injection types.
The velocity distributions at the exit of slot lip for the parallel and vertical injection types are fairly uniform with mild periodical patterns with respect to the injection hole positions. However, the combined injection type increases the nonuniformity of flow distribution with the period equaling twice that of hole-to-hole pitch due to splitting and merging of the ejected flows. The dimensionless temperature distributions at the slot exits differ little with blowing rates, injection types and secondary flow conditions.
In the results of heat/mass transfer measurements, the best cooling performance inside the slot is obtained with the vertical injection type among the three different injection types due to the effects of jet impingement. The lateral distributions of heat/mass transfer coefficients with the inline- and counter-flow paths are more uniform than the normal-flow path. The average heat/mass transfer coefficients with the injection holes are about 2∼5 times higher than that of a smooth two-dimensional slot path.
Measurement of Local Heat Transfer Coefficient and Film Cooling Effectiveness Through Discrete Holes
Authors: Martinez-Botas R. F. , Yuen C. H. N. 
Published: August 2014

An efficient steady-state wide band liquid crystal technique is used to study the film cooling performance of a variety of geometries in a flat plate: a single row of holes, a double row of holes (both in-line and staggered), and a single cooling hole. This method allows temperature information to be captured in one image, without the difficulty involved in a transient experiment. The streamwise inclinations tested are 30°, 60°, and 90°. The freestream is maintained at 13m/s, and at ambient temperature. The range of blowing ratios varied from 0.33 to 2.0. Both heat transfer coefficient and adiabatic cooling effectiveness are measured for all the cases. Air is used to produce a density ratio near unity.
From the range of blowing ratios tested, the most effective film cooling is achieved at a value close to 0.5, for near unity density ratio. It has been revealed that film cooling effectiveness is improved when the jet remains attached to the surface, however, this is generally coupled with an augmentation in heat transfer owing to the disturbance the attached jet causes to the boundary layer. The 30° inclined holes show to be the most effective. Results demonstrate the full coverage capability of liquid crystal thermography.
Heat Transfer Analysis in a Modern DLN Combustor
Authors: Ferrara Giovanni , Innocenti Luca , Migliorini Giacomo , Facchini Bruno , Dean Anthony J. 
Published: August 2014

The increasingly stringent emissions standards in recent years have mandated low gas turbine emissions and thus changed the approach to combustion chamber design. In particular, lean burners based on highly premixed fuel-air flows have become more important. These combustors, termed Dry Low NOx (DLN), can now achieve emissions of 25 ppm and below in commercial operation.
This development together with the inlet turbine temperature increase has resulted in less cooling air for combustion chambers and turbine blade cooling systems. The designer now needs to optimise cooling air flows that control the wall temperature of the components that confine the hot gases. Moreover, much of the air coming from the compressor is used to premix the fuel and only a smaller fraction is now available for cooling processes. In annular combustor configurations the air available for cooling the combustion chamber walls sometimes also has to cool the first stage nozzle. So the pressure loss along the combustor cooling passages has to be limited in order to assure a suitable supply pressure for these downstream cooling passages.
We analysed the cooling air flow around the liner of an annular combustion chamber and we investigated the thermal flux and friction losses. In this paper we show the development of a calculation model that allows the critical components heat transfer analysis of a typical annular combustion chamber. The code developed is based on the generalised 1–D flow treatment. We have used experimental correlations for convection, film cooling and impingement borrowed from works found in literature. The code is provided with a graphical interface that helps the user during the calculation. This code was used in practical application to optimize the PGT5B combustion chamber cooling.
A Study on Models to Simulate Boundary Layer Transition in Turbomachinery Flows
Authors: Müller M. , Gallus H. E. , Niehuis R. 
Published: August 2014

The objective of this paper is to investigate the modeling of transition in turbomachinery flows. Under steady state conditions four modes of transition can be identified. One of them, reverse transition, can be modeled sufficiently well by turbulence models. For the other modes — natural, bypass and separated-flow transition — specific models have to be applied. These transition models are either based on stability analysis or a statistic approach that describes the production and growth of turbulent spots in the intermittent flow.
This paper focuses on separated flow transition. Different models are presented and a classification is attempted. Based on these findings specific models are chosen and implemented into a Navier-Stokes solver to be studied in more detail. First an annular compressor cascade is computed two-dimensionally and the results are compared with experiments. In a second step three-dimensional computations are performed and the effect of transition modeling is analysed.
Gas Turbine Field Performance Determination: Sources of Uncertainties
Authors: Pinelli M. , Spina P. R. 
Published: August 2014

This paper presents an analysis of the uncertainties in the determination of gas turbine health, which arise by using a method of Gas Path Analysis. This method uses field measurements to estimate, through a mathematical model of the gas turbine thermodynamic cycle, the characteristic geometric and performance parameters, which are indices of gas turbine health.
The investigated sources of uncertainties are the inaccuracy of measurements and the necessity of fixing a priori a number of characteristic parameters. This fact implies that variations occurring on these parameters in the actual gas turbine cause an estimation error on the characteristic parameters used as problem variables.
The analysis leads to the selection of the appropriate measurements to be used in the gas turbine health determination and identification of both the most critical measurements and parameters.
The Design and Implementation of a PLC Based Gas Turbine Controller for a Shipboard Application
Authors: Tolotta Vincent P. 
Published: August 2014

A paper will be presented describing the design and development of the Gas Turbine Local Controller replacement used on the Magnetic Minesweeping Gas Turbine Generator (MMGTG) on the US Navy MCM-1 Class of ships. The advent of processor based controllers including PLCs has provided a low cost alternative for control system upgrades when faced with increasing maintenance costs and obsolescence issues of analog and hard relay logic control systems. The replacement controller is a Programmable Logic Controller (PLC) based system linked to a flat panel display and a supervisory control system.
A MMGTG during pulsing operations applies a severe load transient cycle to the gas turbine for the fuel control to meet in a stable and safe manner. The algorithms which employ an adaptive Proportional Integral Derivative (PID) loop control structure with internal limiting constraints based on engine state are used to manage these transients, power turbine entry temperature and a wide range of steady state operation. The controller includes logic for alarming, start/stop and automatic shutdown. The design of the hardwired automatic shutdown logic integrated to the PLC will be presented.
The control system design will be described in terms of its integration to a supervisory network, local control functionality and shipboard considerations. The Human Machine Interface screens of the flat panel display and their design are also considered.
Italian Navy Evaluation Concerning the Use of Electronic Fuel Control and Hydraulic Starters for Fiat - GE LM2500 Gas Turbine
Authors: Maggini Massimo , Giuliano Michele 
Published: August 2014

The LM2500 gas turbine has been used on Italian Navy (ITN) ships for more than twenty years. The first engines were installed onboard the “Lupo” class Frigates during the second half of the 1970’s.
These gas turbines are operated by means of a Hydro-Mechanical Fuel Control (HMFC) system and started by a pneumatic starter. However, it is known that in some of the latest applications of the LM2500 gas turbines, (e.g. direct drive and water jet systems - Military Sealift Command LMSR cargo vessels and Tirrenia Ferries), electronic fuel control systems and hydraulic starters are used to improve the control and maintenance of the engine, and to reduce the number of air bottles and compressors that have to be installed.
The ITN is now evaluating the convenience of using the electronic fuel control systems and hydraulic starters in future surface combatant applications (cruisers, destroyers & frigates) of FIAT GE LM2500 gas turbines.
This paper describes the comparison between the different systems that have been carried out by the ITN in the following fields: operations, maintenance and cost effectiveness.
The Effect of Primary Axis and Low Angle Boundary Misorientation on CMSX-10K Mechanical Properties
Authors: Patel Yakin , Browning Paul F. , Fitzpatrick Michael D. , Schmiedechnekt Dean , Price Allen , Simpson Tammy , Erickson Gary , Harris Ken 
Published: August 2014

The U. S. Department of Energy’s Advanced Turbine Systems (ATS) program supports the development of high efficiency gas turbines for industrial and power generation applications. As part of this program, CMSX-10K, a third generation single crystal Ni-base superalloy, is being considered for use in turbine blade applications in an ATS engine. In support of the design and casting process development of CMSX-10K, assessment of component tolerance to casting defects was performed.
Single crystal specimens with primary axis orientation between 4 and 26 degrees and bicrystal specimens with low angle boundaries (LABs) having between 0 and 18 degrees of misorientation were used. The effects of primary axis misorientation and LABs on critical mechanical properties were evaluated. Primary axis misorientation of greater than 15 degrees reduced tensile and high-cycle fatigue properties. Similarly, stress rupture properties were reduced for primary axis misorientation of greater than 20 degrees. LABs having greater than 10 degrees of misorientation caused significantly reduced stress rupture life. LABs having greater than 12 degrees of misorientation also resulted in reduced tensile and high-cycle fatigue properties.
Microphone Probe for In-Duct Measurement of Gas Turbine Exhaust Noise
Authors: Sacks M. P. , Kawall J. G. , Behboudi R. , Buttell J. 
Published: August 2014

A new probe has been developed for Bruel & Kjaer 6.35 mm (1/4″) microphones in order to allow in-duct measurements in high temperature gas turbine exhaust ducts without exposing the microphone to excessive temperatures. The motivation for this design was the need for a probe system that is easily transported and installed on site.
The new probe is made from readily available 6.35 mm (1/4″) o.d. tubing and compression fittings. It consists of a stem to sample the in-duct acoustic field, a shut off valve, a “T” connector to provide a microphone port remote from the hot gas and an anechoic termination.
The termination provides a true anechoic response down to 20 Hz. The probe provides a smooth, resonant free response between 20 Hz and 20 kHz allowing for accurate calibration and measurement.
This paper describes the probe design and installation details, probe frequency response calibration, probe flanking limit and performance of the anechoic termination. The paper also compares the probe response to theoretical predictions. Relative to other potential in-duct measurement probe systems the new design is seen to be lightweight, compact and inexpensive.
Three Practical Examples of Magnetic Bearing Control Design Using a Modern Tool
Authors: Spirig M. , Schmied J. , Jenckel P. , Kanne U. 
Published: August 2014

The use of magnetic bearing in industrial applications has increased due to their unique properties. Nowadays efficiency and predictability in handling rotors on magnetic bearings is asked with the same standard as conventional rotors on oil or roller bearings.
First of all one must be aware of the special technical properties of magnetic bearing designs. The dynamic behaviour of the rotor combined with requirements of the application define the desired bearing characteristic. With modern tools /1/, covering the mechanical aspects as well as the electronic controllers and their digital implementation on a DSP, these properties can be designed.
However, despite the use of such efficient tools engineering practice is needed. Therefore this paper summarises the major steps in the control design process of industrial applications. Three rotors supported on magnetic bearing with their specific dynamic behaviour are presented:
• A very small high speed spindle (120000 rpm),
• a small, industrial turbo molecular pump rotor (36000 rpm) and
• a large multi-stage centrifugal compressor (600 to 6300 rpm).
The results of the analyses and their experimental verification are given.
Control of Surge for Centrifugal Compression System by Using a Bouncing Ball
Authors: Mizuki Shimpei , Tsujita Hoshio , Hishinuma Yumin 
Published: August 2014

An experimental study for the control of surge in a centrifugal compression system by using a bouncing ball was tried. The bouncing ball was placed on a hole outside of the upper wall of a plenum installed to a delivery of a compressor. The hole was surrounded by a tube and had the conical slope toward the hole. When surge occurred, the ball bounced by the fluctuating pressure force in an irregular manner.
By the irregular fluctuation of the bouncing ball, the frequency of surge was suppressed. The peak in the spectrum caused by surge disappeared. Thus, the simple method to control surge by using the bouncing ball was shown to be effective.
Numerical Simulation of Tip Leakage Flows in Axial Flow Turbines, With Emphasis on Flow Physics: Part I — Effect of Tip Clearance Height
Authors: Tallman J. , Lakshminarayana B. 
Published: August 2014

A pressure-correction based, 3D Navier-Stokes CFD code was used to simulate the effects of turbine parameters on the tip leakage flow and vortex in a linear turbine cascade to understand the detailed flow physics. A baseline case simulation of a cascade was first conducted in order to validate the numerical procedure with experimental measurements. The effects of realistic tip clearance spacing, inlet conditions, and relative endwall motion were then sequentially simulated, while maintaining previously modified parameters. With each additional simulation, a detailed comparison of the leakage flow’s direction, pressure gradient, and mass flow, as well as the leakage vortex and its roll-up, size, losses, location, and interaction with other flow features, was conducted.
Part I of this two-part paper series focuses on the effect of reduced tip clearance height on the leakage flow and vortex. Reduced tip clearance resulted in less mass flow through the gap, a smaller leakage vortex, and less aerothermal losses in both the gap and the vortex. The shearing of the leakage jet and passage flow to which leakage vortex roll-up is usually attributed to was not observed in any of the simulations. Alternative explanations of the leakage vortex’s roll-up are presented. Additional secondary flows that were seen near the casing were also discussed.
A more thorough thesis on the research presented in this paper can be found at the World Wide Web address http://navier.aero.psu.edu/∼jat.
Numerical Simulation of Tip Leakage Flows in Axial Flow Turbines, With Emphasis on Flow Physics: Part II — Effect of Outer Casing Relative Motion
Authors: Tallman J. , Lakshminarayana B. 
Published: August 2014

A pressure-correction based, 3D Navier-Stokes CFD code was used to simulate the effects of turbine parameters on the tip leakage flow and vortex in a linear turbine cascade to understand the detailed flow physics. A baseline case simulation of a cascade was first conducted in order to validate the numerical procedure with experimental measurements. The effects of realistic tip clearance spacing, inlet conditions, and relative endwall motion were then sequentially simulated, while maintaining previously modified parameters. With each additional simulation, a detailed comparison of the leakage flow’s direction, pressure gradient, and mass flow, as well as the leakage vortex and its roll-up, size, losses, location, and interaction with other flow features, was conducted.
Part II of this two-part paper series focuses on the effect of relative motion of the outer casing on the leakage flow and vortex development. Casing relative motion resulted in less mass flow through the gap and a smaller leakage vortex. The structure of the aerothermal losses in the passage changed dramatically when the outer casing motion was incorporated, but the total losses in the passage remained very similar. Additional secondary flows that were seen near the casing are also discussed.
A more thorough thesis on the research presented in this paper can be found at the World Wide Web address http://navier.aero.psu.edu/∼jat.