bluuebunny/crossref_metadata_2025_split huggingface dataset:
ICEMS: Intelligent Condition-Based Engine/Equipment Management System (www.icems.com)
Authors: Jaw Link , Wang Yu-tsung (Jim) , Friend Richard 
Published: July 2014

Health management of a machine, such as a gas turbine engine, offers the potential benefits of efficient operations planning and the reduced cost of ownership. It requires a tight integration of major health management functions, such as trending, failure identification, forecasting, life prediction, operations and maintenance planning. This paper introduces a suite of plug-in tools that enhance the condition monitoring and health management capabilities of operational (or legacy) systems. One of these systems is the U. S. Air Force Comprehensive Engine Trending and Diagnostics System (CETADS), which has been used as the baseline for the development of the tools.
These tools are collectively called the Intelligent Condition-based Engine/Equipment Management System (ICEMS). These tools are configured as software modules, which can be incorporated into an operational health management system individually or as a group. ICEMS modules implement the advanced algorithms containing artificial intelligence, statistical, model-based analysis techniques, and RCM practices. Although these modules have been developed and tested using data from the Pratt & Whitney F100-PW-220 engine in service at Luke Air Force Base, the modules are also generalized to cover many generic machines (or equipment).
Force Measurements in Magnetic Bearings Using Fiber Optic Strain Gauges
Authors: Raymer Stephen G. , Childs Dara W. 
Published: July 2014

A new method for measuring forces in magnetic bearings is presented. Fiber-optic strain gauges (FOSGs) mounted to the side of the magnet poles are used to detect the small levels of strain that the metal experiences as the bearing exerts a force. These strains can be converted into force components, providing measurements with a previously unattainable level of accuracy and precision.
Tests were done using the Magnetic Bearing Test Rig at the Texas A&M University Turbomachinery Laboratory. Two FOSGs were placed approximately 90° apart on two separate poles of one of the bearings, and the strain levels for different load magnitudes and directions were measured. The raw signal has several undesirable attributes that prevent an accurate static measurement. However, dynamic measurements proved to be very effective in the frequency domain, as most of the noise in the signal is confined to frequencies below 1 Hz.
Due to the raw signal characteristics, new techniques for load application and calibration were developed. By using these new approaches, an equation relating reaction force components and strain was generated. This equation provides precise knowledge of any force vector in the bearing. An uncertainty analysis was performed on the resulting equation, providing a measure of resolution and a reduction in error several times more precise than any previous result.
As a result of these findings, magnetic bearings can now be used to perform precise diagnostic analysis, determine rotordynamic coefficients, and improve magnetic bearing design and performance.
Improved Combustion Mixture Control Using a Novel Fuel Injector
Authors: Brundish K. D. , Wilson C. W. 
Published: July 2014

A fuel injector has been designed with the capacity to change effective area and fuel placement by varying the swirl number. This gives more flexibility on fuel/air mixture control than current designs, allowing a potentially wide turndown to be achieved whilst maintaining low emissions at high power. The fuel injector utilises fluidic control, eliminating the need for mechanical moving parts in the hot region commonly found in current variable geometry fuel injector designs.
The concept was evaluated and showed promising improvement in stability compared to the baseline fuel injector. The control flow system, using fluidics, was developed in isolation. The concept and control systems were then combined and evaluated. Although variable swirl using fluidic control was achieved, it was not sufficiently optimised to separate the downstream outer and inner airflow as with the concept design. As such the observed improvement in stability was not as good as expected. However, the ability to control effective area, and fuel placement without the need for moving parts was proven.
It is therefore recommended that further work be performed to allow the optimisation of the device such that controllable improvements in stability performance can be achieved in line with the potential shown with concept testing.
Modulation of a Liquid-Fuel Jet in an Unsteady Cross-Flow
Authors: Anderson Torger J. , Proscia William , Cohen Jeffrey M. 
Published: July 2014

This paper describes an experimental study of a fuel jet in an unsteady cross flow as part of a program to evaluate active control of combustion instabilities that involve acoustic / spray coupling.
The results provide insights into the different physical mechanisms through which the jet and cross flow interact and the degree to which acoustic velocity fluctuations modulate liquid jet mixing, penetration and spray distribution. They also provide a means of evaluating the effectiveness of fuel flow modulation for controlling fuel jet behavior, demonstrating that fluctuations in the downstream spray distribution can be significantly reduced by phased fuel flow modulation. The paper describes a unique method for modulating the fuel and a relatively simple diagnostic for evaluating the fuel spray density and uniformity.
Investigation of Unsteady Gas Mixing Processes in Gas Turbine Burners Applying a Tracer-LIF Method
Authors: Schneiders T. , Hoeren A. , Michalski B. , Pfost H. , Scherer V. , Koestlin B. 
Published: July 2014

The profound understanding of the mixing process of gaseous fuels and air is essential for the development of high temperature gas turbine premix-combustion with low pollutant emissions. At the Chair of Steam and Gas Turbines at the University of Bochum, a new approach has been made to obtain more information on the fuel gas-air mixing process. Investigations were undertaken applying an acetone Tracer-LIF-method with a high temporal resolution. Combined with statistical analysis, it yields insights into spatial and temporal mixture distributions and inhomogeneities.
The test rig operated at ambient conditions represents a generic model for gas mixing processes in gas turbine premix burners. Experiments are undertaken with different injection configurations by varying the geometry and the momentum flux ratio. The results of the investigations for opposed rows of gas injection orifices reveal similar characteristics and dependencies of spatial and temporal mixing distributions on the injection set-up.
Comparison of Numerical and Experimental Results of a Premixed DLE Gas Turbine Combustor
Authors: Eggels Ruud L. G. M. , Brown Christopher T. 
Published: July 2014

A numerical and experimental study on a premixed DLE gas turbine combustor has been performed. Experiments and CFD modelling have been carried out at isothermal and combusting conditions. The measurements were obtained at ERC using two component Laser Doppler Velocimetry. To be able to access the inner part of the combustor, the liners of the combustion chamber were outfitted with quartz windows. Temperature measurements were obtained at a few planes using a thermocouple.
Modelling of the combustor has been performed using an in-house CFD code. The combustion process has been modelled using a global reaction mechanism and a Flame Generated Manifold reaction mechanism in combination with a presumed PDF model to incorporate the effect of turbulent fluctuations. The Flame Generated Manifold method uses a flame library, which has been generated by performing a number of laminar one-dimensional flame calculations at representative conditions.
Comparing the numerical and experimental quite some differences are observed. The CFD model is able to predict the main features of the flow and combustion process, but does not predict the recirculation length accurately. Both combustion models, however, are able to predict the low combustion efficiency measured at the 1atm test condition.
NOx Formation in High-Pressure Jet-Stirred Reactors With Significance to Lean-Premixed Combustion Turbines
Authors: Rutar Teodora , Malte Philip C. 
Published: July 2014

Measurements of NOx and CO in methane-fired, lean-premixed, high-pressure jet-stirred reactors (HP-JSRs) independently obtained by Rutar [1] and Rutar et al. [2] and by Bengtsson [3] and Bengtsson et al. [4] are well predicted assuming simple chemical reactor models and the GRI 3.0 chemical kinetic mechanism. The single-jet HP-JSR of Rutar [1] and Rutar et al. [2] is well modeled for NOx and CO assuming a single PSR for Damköhler number below 0.15. Under these conditions, the estimates of flame thickness indicate the flame zone, that is, the region of rapid oxidation and large concentrations of free radicals, fully fills the HP-JSR. For Damköhler number above 0.15, that is, for longer residence times, the NOx and CO are well modeled assuming two PSRs in series, representing a small flame zone followed by a large post-flame zone. The multi-jet reactor of Bengtsson [3] and Bengtsson et al. [4] is well modeled assuming a large PSR (over 88% of the reactor volume) followed by a short PFR, which accounts for the exit region of the HP-JSR and the short section of exhaust prior to the sampling point. The Damköhler number is estimated between 0.01 and 0.03.
Our modeling shows the NOx formation pathway contributions. Although all pathways, including Zeldovich (under the influence of super-equilibrium O-atom), nitrous oxide, Fenimore prompt, and NNH, contribute to the total NOx predicted, of special note are the following findings: 1) NOx formed by the nitrous oxide pathway is significant throughout the conditions studied; and 2) NOx formed by the Fenimore prompt pathway is significant when the fuel-air equivalence ratio is greater than about 0.7 (as might occur in a piloted lean-premixed combustor) or when the residence time of the flame zone is very short. The latter effect is a consequence of the short lifetime of the CH radical in flames.
Low NOX Combustion for Liquid Fuels: Atmospheric Pressure Experiments Using a Staged Prevaporizer-Premixer
Authors: Lee John C. Y. , Malte Philip C. , Benjamin Michael A. 
Published: July 2014

Low emissions of NOx are obtained for a wide range of liquid fuels by using a staged prevaporizing-premixing injector. The injector relies on two stages of air temperature and fires into a laboratory jet-stirred reactor operated at atmospheric pressure and nominal ϕ of 0.6. The liquid fuels burned are methanol, normal alkanes from pentane to hexadecane, benzene, toluene, two grades of light naphtha and four grades of No. 2 diesel fuel. Additionally, natural gas, ethane and industrial propane are burned. For experiments conducted for 1790 K combustion temperature and 2.3±0.1 ms combustion residence time, the NOx (adjusted to 15% O2 dry) varies from a low of 3.5 ppmv for methanol to a high of 11.5 ppmv for No. 2 diesel fuel. For the most part, the NOx and CO are positively correlated with the fuel carbon to hydrogen ratio (C/H). Chemical kinetic modeling suggests the increase in NOx with C/H ratio is caused in significant part by the increasing super-equilibrium concentrations of O-atom created by the increasing levels of CO burning in the jet-stirred reactor. Fuel bound nitrogen also contributes NOx for the burning of the diesel fuel.
This paper describes the staged prevaporizing-premixing injector, the examination of the injector and the NOx and CO measurements and their interpretation. Optical measurements, using beams of He-Ne laser radiation passed across the outlet stream of the injector, indicate complete vaporization and a small variation in the cross-stream averaged fuel/air ratio. The later is determined by measuring the standard deviation and mean of the transmission of the laser beam passed through the stream. Additional measurements and inspections indicate no pressure oscillations within the injector and no gum and carbon deposition. Thus, the NOx and CO measurements are obtained for fully vaporized, well premixed conditions devoid of preflame reactions within the injector.
A Hybrid System Based on a Personal Turbine (5 kW) and a SOFC Stack: A Flexible and High Efficiency Energy Concept for the Distributed Power Market
Authors: Magistri Loredana , Massardo Aristide , Rodgers Colin , McDonald Colin F. 
Published: July 2014

In this paper a high efficiency and flexible hybrid system representing a new total energy concept for the distributed power market is presented.
The hybrid system is composed of a very small size (5 kW) micro gas turbine (named personal turbine – PT) presented in a companion paper by the authors (McDonald and Rodgers, 2001) coupled to a small size Solid Oxide Fuel Cell (SOFC) stack. The power of the whole system is 36 kW depending on the design parameters assumed for the stack.
The design and off design performance of the hybrid system have been obtained through the use of an appropriate modular code named “HS-SOFC” developed at the University of Genoa (Magistri, 1999) and described in detail in this paper.
The results of the simulation are presented and discussed with particular regards to: choice of the Hybrid System (HS) design point data, HS design point performance, off design performance of PT and SOFC stack, off design performance of the whole HS.
Some preliminary economic results are also included based on different fuel and capital cost scenarios and using the cost of electricity as the parameter for comparison between PT and HS.
A Novel Gas Turbine Concept for Combined Power, Heat and Cooling Generation
Authors: Arriagada Jaime , Rosén Per , Torisson Tord 
Published: July 2014

An attractive and innovative technology for gas turbines for obtaining power, heat and cooling simultaneously has been developed and studied in Lund.
The basic idea behind this technology, called the TRIGENERATION™, is to interrupt the expansion in the gas turbine expander at an elevated pressure level, at which the heat rejection is carried out in a heat exchanger. After that, the expansion of the flue gas continues until ambient pressure, but the temperature is below the ambient temperature. This “negative” temperature difference allows the use of the exhaust for cooling purposes. The performance coefficient, defined as the ratio between all the benefits (power, heat and cooling) and the fuel heat, can reach values higher than 100% (HHV). This technology has its major potential when integrated with “wet” cycles, e.g. HAT and STIG. In such cycles, an easier extraction of the latent heat of vaporization within the humid flue gas is allowed, due to the higher water dew point at higher pressures. In this work, this technology is evaluated through simulations in a heat and mass balance program for the simple cycle gas turbine.
Applications of Gas Turbine Plants With Cooled Compressor Intake Air
Authors: Kakaras E. , Doukelis A. , Scharfe J. 
Published: July 2014

The operation of gas turbines at ambient air temperatures higher than the ISO standard conditions (15°C) causes performance penalties both in the generated power and the efficiency of the engine. At high inlet-air temperatures, there can be a power loss of more than 20% combined with a significant increase in specific fuel consumption, compared to the ISO standard conditions. Thus, over a long period of time, gas turbines have a lower power output and efficiency than the equipment could actually perform.
It is the purpose of this work to present the possibilities and advantages from the integration of an innovative air-cooling system for reducing the gas turbine intake-air temperature. The advantages of this system are demonstrated by examining alternative scenarios of usage, representative of different countries and different climatic conditions.
A Converging Slot-Hole Film-Cooling Geometry: Part 1 — Low-Speed Flat-Plate Heat Transfer and Loss
Authors: Sargison J. E. , Guo S. M. , Oldfield M. L. G. , Lock G. D. , Rawlinson A. J. 
Published: July 2014

This paper presents experimental measurements of the performance of a new film cooling hole geometry - the Converging Slot-Hole or Console. This novel, patented geometry has been designed to improve the heat transfer and aerodynamic loss performance of turbine vane and rotor blade cooling systems. The physical principles embodied in the new hole design are described, and a typical example of the console geometry is presented.
The cooling performance of a single row of consoles was compared experimentally with that of typical 35° cylindrical and fan-shaped holes and a slot, on a large-scale, flat-plate model at engine representative Reynolds numbers in a low speed tunnel with ambient temperature main flow. The hole throat area per unit width is matched for all four hole geometries. By independently varying the temperature of the heated coolant and the heat flux from an electrically heated, thermally insulated, constant heat flux surface, both the heat transfer coefficient and the adiabatic cooling effectiveness were deduced from digital photographs of the colour play of narrow-band thermochromic liquid crystals on the model surface.
A comparative measurement of the aerodynamic losses associated with each of the four film-cooling geometries was made by traversing the boundary layer at the downstream end of the flat plate.
The promising heat transfer and aerodynamic performance of the console geometry have justified further experiments on an engine representative nozzle guide vane in a transonic annular cascade presented in Part 2 of this paper [1].
A Converging Slot-Hole Film-Cooling Geometry: Part 2 — Transonic Nozzle Guide Vane Heat Transfer and Loss
Authors: Sargison J. E. , Guo S. M. , Oldfield M. L. G. , Lock G. D. , Rawlinson A. J. 
Published: July 2014

This paper presents the first experimental measurements on an engine representative nozzle guide vane, of a new film cooling hole geometry, a Converging Slot-Hole or Console. The patented console geometry is designed to improve the heat transfer and aerodynamic performance of turbine vane and rotor blade cooling systems. These experiments follow the successful validation of the console design in low-speed flat-plate tests described in Part 1 of this paper (Sargison et al [1]).
Stereolithography was used to manufacture a resin model of a transonic, engine representative nozzle guide vane in which 7 rows of previously tested fan-shaped film-cooling holes were replaced by 4 rows of consoles. This vane was mounted in the annular vane ring of the Oxford Cold Heat Transfer Tunnel for testing at engine Reynolds numbers, Mach numbers and coolant to mainstream momentum flux ratios using a heavy gas to simulate the correct coolant to mainstream density ratio.
Heat transfer data were measured using wide band thermochromic liquid crystals and a modified analysis technique. Both surface heat transfer coefficient and the adiabatic cooling effectiveness were derived from computer-video records of hue changes during the transient tunnel run. The cooling performance, quantified by the heat flux at engine temperature levels, of the console vane compares favourably with that of the previously tested vane with fan-shaped holes.
The new console film cooling hole geometry offers advantages to the engine designer due to a superior aerodynamic efficiency over the fan-shaped hole geometry. These efficiency measurements are demonstrated by results from mid span traverses of a four hole pyramid probe downstream of the nozzle guide vane.
Film Cooling Effectiveness Downstream of Compound and Fan-Shaped Holes
Authors: Yuen C. H. N. , Martinez-Botas R. F. , Whitelaw J. H. 
Published: July 2014

The steady-state wide band liquid crystal technique is used to study the film cooling performance downstream of a variety of geometries in a flat plate. This technique provides a detailed measurement of both cooling effectiveness and heat transfer coefficient. This paper presents the effects of compound and fan–shaped holes, the effect of streamwise angle variation has been presented at previous meetings. The following configurations are investigated: a single hole, a row of holes with a pitch-to-diameter ratio, p/D, of 3, two inline rows with p/D of 3 and two staggered rows with p/D of 6; all with a stream–wise angle of 30°. The spacing between two rows was chosen as 12.4D. Two lateral injection are investigated: 30° and 60° compound angle. The fan shaped hole used comprised of a lateral expansion of 14° from the original simple cylindrical shape with streamwise inclination of 30°; forward expansion was not incorporated. The length-to-diameter ratio, L/D, was maintained at a value of 4 for all the compound cases, the L/D for the fan shaped-hole was 6, larger due to its physical limitation. The tests were performed with a jet-to-freestream density ratio of 1.5; achieved by using a foreign gas (CO2) injection. The range of momentum flux ratios (M) covered was 0.33 to 1.67.
The row of 30° compound angle holes gave a lower value of effectiveness when compared to the non-compound case at M<0.67, but greater values and coverage at M>1.0, consistent with previous experiments. The row of 60° compound angle gave greater effectiveness, coverage and uniformity than the row of 30° compound at a given blowing ratio; the jet-to-jet interaction was greater for the 60° row due to the added lateral momentum. The row of 60° compound gave an increase of order 100% relative to the non-compounded row for M>1.
Two inline rows of fan-shape holes delivered less effectiveness than the corresponding single row at the same spanwise distance for a given jet fluid mass, or blowing ratio with twice the jet fluid mass. For equal blowing ratios and equal flow rates the fan-shaped hole gave a much higher effectiveness.
Effect of Crossflows on the Discharge Coefficient of Film Cooling Holes With Varying Angles of Inclination and Orientation
Authors: Gritsch Michael , Schulz Achmed , Wittig Sigmar 
Published: July 2014

Measurements of discharge coefficients for five configurations of cylindrical film cooling hole geometries are presented. These comprise holes of varying angles of inclination (α= 30, 45, and 90deg) and orientation (γ= 0, 45, and 90deg) which are tested over a wide range of engine like conditions in terms of internal and external crossflow Mach numbers (Mam=0…1.2, Mac=0…0.6) as well as pressure ratios (ptc/pm=1…2.25).
Results show that discharge coefficients do not solely depend on hole geometry but are also profoundly affected by the internal and external crossflow conditions. The effect of increasing the orientation angle on the discharge behavior is very similar to the effect of increasing the inclination angle. Both result in higher losses particularly at the cooling hole inlet while the losses at the hole exit are only slightly affected.