bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat Transfer and Pressure Drop Measurements in a High Solidity Pin Fin Array With Variable Hole Size Incremental Impingement
Authors: Sheikhmohamed A. A. , Soma L. W. , Ames F. E. , Acharya S. 
Published: August 2017

Leading edge heat loads on turbine vanes diminish relative to fully turbulent heat loads with increasing Reynolds number. Leading edge regions of turbine nozzles are often cooled using showerhead arrays while the near pressure surface is often protected with rows of shaped holes. However, in environments with impurities in the fuel or air cooling holes are susceptible to clogging and constitute sites where deposition can begin. Showerhead film cooling can be disruptive to downstream boundary layer development and film cooling. Also, high turbulence levels which normally exist in these regions quickly mix away film cooling protection. Consequently, internal cooling has many advantages over showerhead cooling and pressure surface film protection. Internal cooling produces higher levels of internal effectiveness and spent cooling air can be subsequently directed to near optimum discharge geometries for film protection.
Conventional cooling methods have disadvantages when trying to cool leading edge regions and near pressure surfaces. Cooling air in pin fin arrays quickly heats up developing a lower cooling potential. Impingement arrays have issues due to increasing crossflows which deflect impingement jets and insulate the surfaces needing cooling. Incremental impingement overcomes these disadvantages by incrementally adding cooling air where needed and overcoming crossflows by hiding impingement jets behind high solidity pedestals.
This paper presents heat transfer and pressure drop results for an incremental impingement array with variable hole size. The experimental measurements were acquired using a bench scale test rig. The array Reynolds numbers tested ranged from 5000 to 60,000 based on the average velocity of the accumulated flow through the minimum array flow area. The array consisted of an initial impingement row between a row of elongated pedestals followed by 7 additional high solidity round pedestal rows in a staggered arrangement. Impingement holes of variable sizes were placed behind even rows. Generally, the array consisted of rows of round pins spaced at 1.625 diameters in the spanwise direction, 1.074 diameters in the streamwise direction with a channel height to diameter ratio of 0.5. Impingement hole to pin diameter ratios used included d/D of 0.295, 0.351, and 0.417. Hole configurations were limited to arrays where the hole area upstream from the last row of holes was no more than 109% of the minimum array flow area. Heat transfer measurements were acquired at a constant temperature within the array and are reported on a row averaged basis in terms of the local internal effectiveness and the cooling parameter.
An Emerging Technique for Low-Concentration Measurement of Particulate Emissions From Gas-Fired Gas Turbines
Authors: Crosby Kevin J. , England Glenn C. 
Published: August 2017

Concentrations of particulate matter (PM, PM10, PM2.5) from gas-fired gas turbines typically are near or below the overall method detection and quantitation limits of traditional hot filter/cooled impinger methods used for PM/PM10/PM2.5 emissions measurements (e.g., USEPA reference methods 5, 201A, 202). The test results can be highly variable, and may significantly overstate emissions even with application of best practices optimized to minimize bias and variability.
An emerging test protocol for modifying USEPA Conditional Test Method 39 (CTM 39), a dilution sampling method for determining PM10/PM2.5 emissions from stationary sources, was used to accurately measure much lower PM concentrations. The lower concentrations are believed to be more representative of actual PM emissions from gas turbines. The modifications include adding ambient air sample collection and analysis methods for improved method sensitivity. Data from several testing programs are presented to illustrate the limitations of traditional methods for determining PM emissions, including measurement challenges associated with post-combustion emission controls such as SCR. Results from the modified method are presented to demonstrate the potential improvement compared with traditional hot filter/cooled impinger methods.
Analytical Investigation of a Thermal-Supercharged Internal Combustion Engine Compounded With Organic Rankine Cycle for Waste Heat Recovery
Authors: Jiménez-Arreola Manuel , Dal Magro Fabio , Romagnoli Alessandro , Chiong Meng Soon , Rajoo Srithar , Martinez-Botas Ricardo F. 
Published: August 2017

Waste heat recovery is seen as one of the key enablers in achieving powertrain of high efficiency. The exhaust waste heat from an internal combustion engine (ICE) is known to be nearly equivalent to its brake power. Any energy recovered from the waste heat, which otherwise would be discarded, may directly enhance the overall thermal efficiency of a powertrain. Rankine cycle (indirect-recovery method) has been a favorable mean of waste heat recovery due to its rather high power density yet imposing significantly lesser back pressure to the engine compared to a direct-recovery method.
This paper presents the analytical investigation of a thermal-supercharged ICE compounded with Rankine cycle. This system removes the turbocharger turbine to further mitigate the exhaust back pressure to the engine, and the turbocharger compressor is powered by the waste heat recovered from the exhaust stream. Extra caution has been taken when exchanging the in/output parameters between the engine and Rankine cycle model to have a more realistic predictions. Such configuration improves the engine BSFC performance by 2.4–3.9%. Water, Benzene and R245fa are found to be equally good choice of working fluid for the Rankine cycle, and can further advance the BSFC performance by 4.0–4.8% despite running at minimum pressure setting. The off-design analyses suggested the operating pressure of Rankine cycle and its expander efficiency have the largest influence to the gross system performance.
Research on Fluid Flow Stability With Baffles of Different Size in a Hydrodynamic Coupling During Partially Liquid-Filled Operating Conditions
Authors: Yan Qingdong , An Yuanyuan , Wei Wei 
Published: August 2017

The hydrodynamic coupling is a power transmission device dependent on the liquid medium momentum change with the advantage of slow shock, isolation of torsional vibration, start light load and overload protection, which is applied in engineering, mining, construction, lifting the transport machinery, et al[1]. The hydrodynamic coupling without inner ring usually works in partially liquid-filled operating conditions, when the flow state changes suddenly with the rotating speed ratio changing. This may lead to unstable gas-liquid two-phase flow in a hydrodynamic coupling in a certain ratio range. To improve the stability of two-phase flow, a baffle is set inside the circulatory circle of a hydrodynamic coupling. The baffle blocks part of the flow area between two wheels in the hydrodynamic coupling. The size of baffle plays an important role on the effect for improving the flow stability.
To investigate the influence of the baffle to the internal flow stability, the two-phase flow (liquid-filling rate is 80%) in hydrodynamic couplings with baffles in different sizes and without baffles were studied by Computational Fluid Dynamics (CFD) numerical simulation with the rotating speed of pump at constant 2200 r/min and rotating speed of turbine changing from 0 to 2200r/min. The corresponding distributions of streamlines and characteristics curves were obtained.
Through the analysis of turbine torque and efficiency, it is verified that the baffle could improve the flow stability, and the different distributions of streamline could explain the reason. In addition, optimal range of baffle size c = 30% ∼ 40% is obtained by analyzing the simulation results. This will provide a basis for the improvement of design in the hydrodynamic coupling.
Mode Shapes and Dominant Frequency Predictions in a Swirl Stabilized Premixed Air-Methane Combustor Using Modal Analysis and Large Eddy Simulations (LES)
Authors: Jadhav Tushar , Orsino Stefano , Patwardhan Saurabh , Nakod Pravin 
Published: August 2017

Stringent emission regulations force the gas turbine combustor community to come up with new designs. Lean Premixed (LPM) combustion is gaining popularity to meet the emission regulations. However, lean combustion process is prone to other issues like combustion instabilities and noise. Self-excited combustion instabilities in a gas turbine play vital role in the life cycle of combustor, noise generation and pollutant formation. If the instabilities in combustor dominate at natural modes, there are risks of resonance which can lead to bursting damage to the combustors.
In the present work, modal analysis is carried out to predict the longitudinal and the transverse modes in a swirl-stabilized premixed methane-air combustor. The geometrical details and the boundary conditions used in this work are described in Broda et al. [1]. In addition to the modal analysis, Large Eddy Simulations (LES) with Flamelet Generation Manifold (FGM) combustion model are carried out to find out the instabilities and their sources. In the large eddy simulation, at the inlet of the combustor, a broadband impedance boundary condition is used. This will consider the effect of upstream travelling acoustic waves at the inlet. The outlet of combustor is specified with non-reflecting boundary condition. The inlet mass flow rate and the temperature conditions are consistent with Broda et al. [1]. The longitudinal and transverse modes predicted by the modal analysis and the dominant frequency predicted in the LES case are compared with the experimentally observed values. The predicted first longitudinal mode at ∼1760 Hz compares well with the experimental value of 1760 Hz. Predicted values of first and second tangential modes at 10459 Hz and 17344 Hz are also in good agreement with the experimental measurement. The dominant frequency predicted by the LES simulation is 1940 Hz. After applying the appropriate correction to this value for the wall heat transfer effect, it is in-line with that obtained from the modal analysis and the experiments. The spectral analysis at different probe location in LES simulation shows higher thermo-acoustic coupling at natural frequencies. In this work, the effect of variation in inlet swirl number and the temperature is also studies. The predicted trends in the change in dominant frequency with the increase in inlet swirl number and inlet temperature are captured accurately. For each condition, calculations were performed for about four flow-through times (around 12 ms) after the flow field had reached to its limit cycle to obtain statistically steady condition.
Including Pivot Friction in Pad Motion for a Tilting Pad Journal Bearing With Ball-Socket Pivots
Authors: He Feng 
Published: August 2017

Tilting pad journal bearing has its wide application in turbomachinery. For years, frictionless contact has been assumed for all the contact types in bearing coefficients prediction of tilting pad bearings. Existing experimental data demonstrates contact friction does present in pivots and can prevent pads from effective tilting, which is especially true for the surface contact pivot, e.g. ball-socket pivot. However, no open literature is available to discuss individual pad motion with consideration of pivot contact friction and document the effects on the dynamic behaviors of tilting pad bearings. This paper tries to improve the understanding in this area by discussing the pad motion of a tilting pad bearing with ball-socket pivots subject to pivot friction. A model, which couples the journal motion, hydrodynamic pressure from oil film and contact pressure within the pivots, is established. Instead of Hertz contact, a conformal contact model is applied for the ball-socket contact. Through the coupled transient analyses, the effects of contact friction coefficients, bearing dynamic and static loading, and pivot size on pads motion of a 5-pads load-on-pad bearing are considered and compared.
The results show that the presence of friction within ball-socket pivots does not guarantee “locked up” pads motion, but only limits pads from effective tilting for a given range of friction coefficients. Larger dynamic load increases pad tilting amplitude; this does not mean that enlarged tilting magnitudes reduce pivot friction moments for the pads. With varying bearing loads, the pivot friction could result in non-synchronous motion of pads tilting and pivots deformation and bring these non-synchronous components into the journal vibration. Size-reduced pivots are found to diminish the effects of pivot friction and offer preferred pads dynamics and journal vibration.
Large Eddy Simulations of a Pressurized, Partially-Premixed Swirling Flame With Finite-Rate Chemistry
Authors: Jella Sandeep , Gauthier Pierre , Bourque Gilles , Bergthorson Jeffrey , Bulat Ghenadie , Rogerson Jim , Sadasivuni Suresh 
Published: August 2017

Finite-rate chemical effects at gas turbine conditions lead to incomplete combustion and well-known emissions issues. Although a thin flame front is preserved on an average, the instantaneous flame location can vary in thickness and location due to heat losses or imperfect mixing. Post-flame phenomena (slow CO oxidation or thermal NO production) can be expected to be significantly influenced by turbulent eddy structures. Since typical gas turbine combustor calculations require insight into flame stabilization as well as pollutant formation, combustion models are required to be sensitive to the instantaneous and local flow conditions. Unfortunately, few models that adequately describe turbulence-chemistry interactions are tractable in the industrial context. A widely used model capable of employing finite-rate chemistry, is the Eddy Dissipation Concept (EDC) model of Magnussen. Its application in large eddy simulations (LES) is problematic mainly due to a strong sensitivity to the model constants which were based on an isotropic cascade analysis in the RANS context.
The objectives of this paper are: (i) To formulate the EDC cascade idea in the context of LES; and (ii) To validate the model using experimental data consisting of velocity (PIV measurements) and major species (1-D Raman measurements), at four axial locations in the near-burner region of a Siemens SGT-100 industrial gas turbine combustor.
Optimal Gas Turbine Power Plant Operation Regarding Fuel and Maintenance Cost
Authors: Waniczek Phillip , Therkorn Dirk , Lilley Darrel 
Published: August 2017

This paper describes a method that optimizes the commercial benefit by modifying gas turbine control parameters like turbine inlet temperature and variable inlet guide vane position for any dispatched power plant load. The method is a trade-off between best efficiency in the component characteristic together with higher efficiency due to increased turbine inlet temperature and lifetime. With commercial data, both effects are transferred into costs and an optimization routine identifies controller settings for minimum power plant operation cost.
Test cases demonstrate the advantage of the operational cost optimization. Costs are calculated based on historic plant data with the original and the optimized operation concept. Although savings per operating hour are small, the accumulated savings over years or major inspection intervals are significant. It could be demonstrated that in regions with high fuel prices the commercial benefit of the optimized gas turbine operating concept sums up to “several million dollars” of savings. Parametric and sensitivity studies show the effect of the main parameters.
Dispatch power optimization is not subject of the presented model, but can be implemented on top of the proposed concept.
All in all, this work demonstrates and quantifies the commercial benefits when todays and future digital industrial capabilities are applied to gas turbine operation concepts and strategies. The proposed digital approach has the advantage of minimum investment and is attractive for gas turbine operators to generate electricity at lower costs and fuel consumption, increasing revenues and minimizing environmental impact.
Equine Arteritis Virus Elicits a Mucosal Antibody Response in the Reproductive Tract of Persistently Infected Stallions
Authors: Carossino Mariano , Wagner Bettina , Loynachan Alan T. , Cook R. Frank , Canisso Igor F. , Chelvarajan Lakshman , Edwards Casey L. , Nam Bora , Timoney John F. , Timoney Peter J. , Balasuriya Udeni B. R. 
Published: August 2017

ABSTRACT
Equine arteritis virus (EAV) has the ability to establish persistent infection in the reproductive tract of the stallion (carrier) and is continuously shed in its semen. We have recently demonstrated that EAV persists within stromal cells and a subset of lymphocytes in the stallion accessory sex glands in the presence of a significant local inflammatory response. In the present study, we demonstrated that EAV elicits a mucosal antibody response in the reproductive tract during persistent infection with homing of plasma cells into accessory sex glands. The EAV-specific immunoglobulin isotypes in seminal plasma included IgA, IgG1, IgG3/5, and IgG4/7. Interestingly, seminal plasma IgG1 and IgG4/7 possessed virus-neutralizing activity, while seminal plasma IgA and IgG3/5 did not. However, virus-neutralizing IgG1 and IgG4/7 in seminal plasma were not effective in preventing viral infectivity. In addition, the serological response was primarily mediated by virus-specific IgM and IgG1, while virus-specific serum IgA, IgG3/5, IgG4/7, and IgG6 isotype responses were not detected. This is the first report characterizing the immunoglobulin isotypes in equine serum and seminal plasma in response to EAV infection. The findings presented herein suggest that while a broader immunoglobulin isotype diversity is elicited in seminal plasma, EAV has the ability to persist in the reproductive tract, in spite of local mucosal antibody and inflammatory responses. This study provides further evidence that EAV employs complex immune evasion mechanisms during persistence in the reproductive tract that warrant further investigation.
Multiplex Real-Time PCR Assay for Simultaneous Identification of Neisseria gonorrhoeae and Its Ciprofloxacin Susceptibility Status
Authors: Perera Sumudu R. , Khan Nurul H. , Martin Irene , Taheri Ali , Parti Rajinder P. , Levett Paul N. , Horsman Greg B. , Kusalik Anthony , Dillon Jo-Anne R. 
Published: August 2017

ABSTRACT

A real-time PCR (RT-PCR) assay was designed for the simultaneous identification of
Neisseria gonorrhoeae
and its ciprofloxacin susceptibility status. A SYBR green-based multiplex RT-PCR format was used; it comprised two different forward primers and a common reverse primer to detect single nucleotide polymorphisms (SNPs) in
gyrA
of
N. gonorrhoeae
. The primer pairs were evaluated for their sensitivity and specificity using genomic DNA from 254
N. gonorrhoeae
isolates (82 were ciprofloxacin susceptible and 172 were ciprofloxacin resistant) and 23 non-
N. gonorrhoeae
species isolates. The performance of the primers was validated using genomic DNA from 100 different
N. gonorrhoeae
isolates (46 were ciprofloxacin susceptible and 54 were ciprofloxacin resistant) and 52 non-
N. gonorrhoeae
isolates. The latter panel was revalidated by testing 99 (46 isolates were ciprofloxacin susceptible and 53 isolates were ciprofloxacin resistant) of the
N. gonorrhoeae
isolates and 23 non-
N. gonorrhoeae
isolates. These primers detected
N. gonorrhoeae
and its ciprofloxacin susceptibility status with over 99% sensitivity and specificity for all panels tested. This assay has the potential to be an inexpensive and rapid test for the simultaneous identification of
N. gonorrhoeae
and its ciprofloxacin susceptibility status.
Contributions of Individual Domains to Function of the HIV-1 Rev Response Element
Authors: O'Carroll Ina P. , Thappeta Yashna , Fan Lixin , Ramirez-Valdez Edric A. , Smith Sean , Wang Yun-Xing , Rein Alan 
Published: August 2017

ABSTRACT
The HIV-1 Rev response element (RRE) is a 351-base element in unspliced and partially spliced viral RNA; binding of the RRE by the viral Rev protein induces nuclear export of RRE-containing RNAs, as required for virus replication. It contains one long, imperfect double helix (domain I), one branched domain (domain II) containing a high-affinity Rev-binding site, and two or three additional domains. We previously reported that the RRE assumes an “A” shape in solution and suggested that the location of the Rev binding sites in domains I and II, opposite each other on the two legs of the A, is optimal for Rev binding and explains Rev's specificity for RRE-containing RNAs. Using small-angle X-ray scattering (SAXS) and a quantitative functional assay, we have now analyzed a panel of RRE mutants. All the results support the essential role of the A shape for RRE function. Moreover, they suggest that the distal portion of domain I and the three crowning domains all contribute to the maintenance of the A shape. Domains I and II are necessary and sufficient for substantial RRE function, provided they are joined by a flexible linker that allows the two domains to face each other.

IMPORTANCE
Retroviral replication requires that some of the viral RNAs transcribed in the cell nucleus be exported to the cytoplasm without being spliced. To achieve this, HIV-1 encodes a protein, Rev, which binds to a complex, highly structured element within viral RNA, the Rev response element (RRE), and escorts RRE-containing RNAs from the nucleus. We previously reported that the RRE is “A” shaped and suggested that this architecture, with the 2 legs opposite one another, can explain the specificity of Rev for the RRE. We have analyzed the functional contributions of individual RRE domains and now report that several domains contribute, with some redundancy, to maintenance of the overall RRE shape. The data strongly support the hypothesis that the opposed placement of the 2 legs is essential for RRE function.