bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Outlook for Radical Aero Engine Intercooler Concepts
Authors: Petit Olivier , Xisto Carlos , Zhao Xin , Grönstedt Tomas 
Published: September 2016

A state of the art turbofan engine has an overall efficiency of about 40%, typically composed of a 50% thermal and an 80% propulsive efficiency. Previous studies have estimated that intercooling may improve fuel burn on such an engine with a 3–5% reduction depending on mission length. The intercooled engine benefits stem firstly from a higher Overall Pressure Ratio (OPR) and secondly from a reduced cooling flow need. Both aspects relate to the reduced compressor exit temperature achieved by the intercooler action. A critical aspect of making the intercooler work efficiently is the use of a variable intercooler exhaust nozzle. This allows reducing the heat extracted from the core in cruise operation as well as reducing the irreversibility generated on the intercooler external surface which arises from bypass flow pressure losses. In this respect the improvements, higher OPR and lower cooling flow need, are achieved indirectly and not by directly improving the underlying thermal efficiency.
This paper discusses direct methods to further improve the efficiency of intercooled turbofan engines, either by reducing irreversibility generated in the heat exchanger or by using the rejected heat from the intercooler to generate useful power to the aircraft. The performance improvements by using the nacelle wetted surface to replace the conventional intercooler surface is first estimated. The net fuel burn benefit is estimated at 1.6%. As a second option a fuel cooled intercooler configuration, operated during the climb phase, is evaluated providing a net fuel burn reduction of 1.3%.
A novel concept that uses the rejected heat to generate additional useful power is then proposed. A secondary cycle able to convert rejected intercooler heat to useful thrust is used to evaluate three possible scenarios. The two first cases investigate the impact of the heat transfer rate on the SFC reduction. As a final consideration the geared intercooled engine cycle is re-optimized to maximize the benefits of the proposed heat recovery system. The maximum SFC improvement for the three cycles is established to 2%, 3.7% and 3%.
Preliminary Design and Performance of Counter Rotating Turbines for Open Rotors: Part II — 0-D Methodology and Case Study for a 160 PAX Aircraft
Authors: Bellocq Pablo , Garmendia Inaki , Legrand Jordane , Sethi Vishal 
Published: September 2016

Direct Drive Open Rotors (DDORs) have the potential to significantly reduce fuel consumption and emissions relative to conventional turbofans. However, this engine architecture presents many design and operational challenges both at engine and aircraft level. At preliminary design stages, a broad design space exploration is required to identify potential optimum design regions and to understand the main trade offs of this novel engine architecture. These assessments may also aid the development process when compromises need to be performed as a consequence of design, operational or regulatory constraints.
Design space exploration assessments are done with 0-D or 1-D models for computational purposes. These simplified 0-D and 1-D models have to capture the impact of the independent variation of the main design and control variables of the engine. Historically, it appears that for preliminary design studies of DDORs, Counter Rotating Turbines (CRTs) have been modelled as conventional turbines and therefore it was not possible to assess the impact of the variation of the number of stages (Nb) of the CRT and rotational speed of the propellers. Additionally, no preliminary design methodology for CRTs was found in the public domain.
Part I of this two-part publication proposes a 1-D preliminary design methodology for DDOR CRTs which allows an independent definition of both parts of the CRT. A method for calculating the off-design performance of a known CRT design is also described.
In Part II, a 0-D design point efficiency calculation for CRTs is proposed and verified with the 1-D methods. The 1-D and 0-D CRT models were used in an engine control and design space exploration case study of a DDOR with a 4.26m diameter an 10% clipped propeller for a 160 PAX aircraft. For this application:
• the design and performance of a 20 stage CRT rotating at 860 rpm (both drums) obtained with the 1-D methods is presented.
• differently from geared open rotors, negligible cruise fuel savings can be achieved by an advanced propeller control.
• for rotational speeds between 750 and 880 rpm (relatively low speeds for reduced noise), 22 and 20 stages CRTs are required.
• engine weight can be kept constant for different design rotational speeds by using the minimum required Nb.
• for any target engine weight, TOC and cruise SFC are reduced by reducing the rotational speeds and increasing Nb (also favourable for reducing CRP noise). However additional CRT stages increase engine drag, mechanical complexity and cost.
Externally Fired Gas Turbine: Layout Optimization for Micro CHP Generation With Residual Biomass Firing
Authors: Zampilli Mauro , Bidini Gianni , Laranci Paolo , Fantozzi Francesco 
Published: September 2016

The Externally Fired Gas Turbine (EFGT) systems allows the use of unrefined fuels, such as biomass and waste in cogeneration arrangement for adequate efficiencies and high reliability, with respect to internal combustion systems based on gasification. The technology has some technological barriers related to thermal and mechanical resistance of the high temperature heat exchanger (HTHE), which is subject to fouling and corrosion phenomena of the parts exposed to flue gas and fly ash deposits. In this paper an investigation aimed to optimize a 100 kWel, Externally Fired micro Gas Turbine (EFmGT) for combined heat and power generation is presented and discussed. A techno-economic analysis was performed for different plant layouts which are energetically analysed for the case of complete external combustion and co-firing with natural gas, comparing power production, electrical and global efficiency. Each layout was studied by means of mass and energy balance.
An economic analysis is also provided, focused on a comparison of initial investment, NPV and IRR. In the economic analysis the best feed in tariff for energetic valorisation of residual biomass was used to calculate the revenue of electric energy generated from biomass.
Adapting the Zero-Emission Graz Cycle for Hydrogen Combustion and Investigation of Its Part Load Behaviour
Authors: Sanz Wolfgang , Braun Martin , Jericha Herbert , Platzer Max F. 
Published: September 2016

A modern energy system based on renewable energy like wind and solar power inevitably needs a storage system to provide energy on demand. Hydrogen is a promising candidate for this task. For the re-conversion of the valuable fuel hydrogen to electricity a power plant of highest efficiency is needed.
In this work the Graz Cycle, a zero emission power plant based on the oxy-fuel technology, is proposed for this role. The Graz Cycle originally burns fossil fuels with pure oxygen and offers efficiencies up to 65 % due to the recompression of about half of the working fluid. The Graz Cycle is now adapted for hydrogen combustion with pure oxygen so that a working fluid of nearly pure steam is available. The changes in the thermodynamic layout are presented and discussed. The results show that the cycle is able to reach a net cycle efficiency based on LHV of 68.5 % if the oxygen is supplied “freely” from hydrogen generation by electrolysis.
An additional parameter study shows the potential of the cycle for further improvements. The high efficiency of the Graz Cycle is also achieved by a close interaction of the components which makes part load operation more difficult. So in the second part of the paper strategies for part load operation are presented and investigated. The thermodynamic analysis predicts part load down to 30 % of the base load at remarkably high efficiencies.
An Innovative Approach to Model Temperature Influence on Particle Deposition in Gas Turbines
Authors: Agati Giuliano , Borello Domenico , Rispoli Franco , Venturini Paolo 
Published: September 2016

The mechanism of deposit formation on the blade surfaces of a cooled turbine vane is investigated numerically. The prediction of dispersed particles trajectories is affected by temperature, by the mechanics of impact on a solid surface, and by the interaction between particles and film cooling jets and all these aspects must be accounted for. The model here proposed is obtained as a high temperature extension of the well-known Thornton and Ning (1998) approach in a temperature interval ranging between 500 K (where basic model — based on an elastic-plastic impact mechanism assumption — holds) and 1500 K (where the critical viscosity model of Walsh et al., 1990 is usually employed). The transition between the two extreme conditions is modelled through a temperature-driven modification of the mechanical properties of both particles and target surfaces.
Our computations demonstrate that the updated model is able to return credible predictions of deposit formation when compared with the baseline models of Thornton and Ning and of Walsh and co-authors. Moreover in the region where particles bounce off, the model predict the coefficient of restitution according to the actual mechanical properties of particles, thus providing a better particle dynamics description than in both the critical viscosity and original Thornton and Ning models.
Fan Performance Scaling With Inlet Distortions
Authors: Defoe J. J. , Hall D. K. 
Published: September 2016

Applications such as boundary-layer-ingesting fans, and compressors in turboprop engines require continuous operation with distorted inflow. A low-speed axial fan with incompressible flow is studied in this paper. Previous work in the literature has shown that the same flow mechanisms contributing to the response of a fan to distortion are at play in incompressible and transonic flows. The objective is to determine how fan performance scales as the type and severity of inlet distortion varies at the design flow coefficient.
A distributed source term approach to modeling the rotor and stator blade rows is used in numerical simulations in this paper. The approach has been shown to capture overall stage performance and flow field behavior with distortions having length scales much longer than the blade pitch. The approach requires only knowledge of the blade geometry, but the model does not include viscous losses. As a result, efficiency is not assessed but instead a metric based on changes in diffusion factor is defined which is conjectured to be related to efficiency changes.
Distortions in stagnation pressure, swirl, and stagnation temperature are considered. By studying the distortions individually, it is found that the diffusion metric scales linearly with the intensity of the distortions (i.e. the ratio of minimum to maximum values) but that changes in distortion location relative to the fan axis produce nonlinear changes in the diffusion metric. Combinations of distortions are also studied and it is found that the diffusion metric associated with the combined distortion can be predicted using a summation procedure for the metrics associated with the individual constituent distortions. The mechanism found to govern the effectiveness of this summation procedure is the incidence distortions at rotor and stator inlet.
Meanline Modeling of a Radial-Inflow Turbine Nozzle With Supersonic Expansion
Authors: Li Shuo , Krivitzky Eric M. , Qiu Xuwen 
Published: September 2016

High pressure ratio, radial-inflow turbines typically experience supersonic expansion in the nozzle section. Accurate estimation of the flow conditions and velocity triangle at the nozzle outlet is of critical importance in correctly predicting the overall turbine performance. The meanline modeling of such a nozzle requires special attention, due to the significantly altered flow field downstream of the throat.
In this study, the flow field of a supersonic expansion nozzle is investigated, using a three-dimensional (3D) computational fluid dynamics (CFD) simulation calibrated with test data. Three different CFD configurations are explored: the nozzle alone, the nozzle plus rotor coupled with a mixing plane, and the nozzle plus rotor coupled with the nonlinear harmonic (NLH) method. These configurations are compared to each other to gauge the effect of the rotor and stator interaction and the potential for error in establishing the velocity triangles. The exit vane angle, number of vanes, and expansion ratio across the nozzle are systematically varied to provide the data as the base for nozzle modeling. Finally, a meanline method is proposed to calculate the pressure loss and flow deviation at the nozzle outlet and is compared with CFD results.
Numerical Research on the Mixing Mechanism of Lobed Mixer With New De-Swirling Structure
Authors: Lei Zhijun , Gong Jianbo , Zhang Yanfeng , Su Shangmei , Hu Chunyan 
Published: September 2016

A detailed numerical simulation is presented to investigate the new de-swirling methods and their effect on the mixing mechanisms of a turbofan mixer with 12 lobes. The numerical simulation employed a commercial solver, ANSYS CFX, using k-ω SST model. The core-to-bypass temperature ratio and pressure ratio were set to 2.59, and 0.97 respectively, giving the Mach number of 0.66 and bypass ratio of 2.65 at mixing nozzle outlet. The inlet swirl typically accelerates the jet-flow mixing by enhancing the vortices intensity and interaction, but leakage swirling flow can cause a three-dimensional separation bubble and the recirculation zone resulting in the dramatic increasing the total pressure loss and thrust loss. Removal of the leakage swirling flow between the lobes’ trough and centre-body was the key to limit the negative influence of inlet swirl.
Two IGV design were investigated, DS1 and DS2. DS1 was installed at the upstream of the lobed mixer, could remove the negative effect of inlet swirl properly, but also inhibited the active role of the inlet swirl. The total pressure and thrust loss reduced by 0.31% and 3.8%, respectively, but the mixing efficiency also decreased by 1.72%. DS2, an integrated strut with the lobed mixer design, not only ensured the structure strength of the lobed mixer, but also reduced the length and weight of the exhaust system. This method suppressed the flow separation bubble on centre-body to some extent, and eliminated the recirculation zone downstream of the cenrebody, resulting in the total pressure loss decrease of 0.31% and thrust gain of 3.63%. On the other hand, the method DS2 also made full use of the inlet swirl to enhance the jet-flow mixing, resulting in the mixing efficiency increased 1.54% compared with that of the DS1 case. Under the off-design conditions with the incidence angle of ±10°, the aerodynamic performance of the DS2 cases didn’t changed too much such as the DS1 cases.
Design of a Centrifugal Turbo Compressor With the Working Fluid Water for the Operation in a Hybrid Sorption/Compression Heat Pump Cycle
Authors: Eckert Thomas , Dostal Leo , Helm Martin , Schweigler Christian 
Published: September 2016

In various applications the use of sorption chillers and heat pumps is limited by the available temperature level of the driving heat source or the heat sink for export of reject heat. These constraints can be overcome by integrating an efficient high-speed transonic turbo compressor into the internal cycle of a thermally driven water/lithium bromide absorption heat pump.
The operation in a hybrid heat pump with the refrigerant water implies specific challenges for the design of the compressor: Saturation pressures in the sub-atmospheric range, low vapor density, high volume flows and a targeted pressure ratio of 3 result in high impeller tip speeds with machine Mach numbers close to 1. Here the authors present a theoretical design study based on a numerical simulation of a centrifugal compressor, targeted at the given operating conditions. Evaluation of the results is conducted with regard to the relevant thermodynamic and fluid mechanic figures. The optimization of the impeller geometry comprises both fluid dynamic behavior and structural stability.
Highlights of the 11th International Bordetella Symposium: from Basic Biology to Vaccine Development
Authors: Carbonetti Nicholas H. , Wirsing von König Carl Heinz , Lan Ruiting , Jacob-Dubuisson Francoise , Cotter Peggy A. , Deora Rajendar , Merkel Tod J. , van Els Cécile A. , Locht Camille , Hozbor Daniela , Rodriguez Maria E. 
Published: September 2016

ABSTRACTPertussis is a severe respiratory disease caused by infection with the bacterial pathogenBordetella pertussis. The disease affects individuals of all ages but is particularly severe and sometimes fatal in unvaccinated young infants. OtherBordetellaspecies cause diseases in humans, animals, and birds. Scientific, clinical, public health, vaccine company, and regulatory agency experts on these pathogens and diseases gathered in Buenos Aires, Argentina from 5 to 8 April 2016 for the 11th InternationalBordetellaSymposium to discuss recent advances in our understanding of the biology of these organisms, the diseases they cause, and the development of new vaccines and other strategies to prevent these diseases. Highlights of the meeting included pertussis epidemiology in developing nations, genomic analysis ofBordetellabiology and evolution, regulation of virulence factor expression, new model systems to studyBordetellabiology and disease, effects of different vaccines on immune responses, maternal immunization as a strategy to prevent newborn disease, and novel vaccine development for pertussis. In addition, the group approved the formation of an InternationalBordetellaSociety to promote research and information exchange on bordetellae and to organize future meetings. A new Bordetella.org website will also be developed to facilitate these goals.
Burkholderia pseudomallei: Challenges for the Clinical Microbiology Laboratory
Authors: Hemarajata Peera , Baghdadi Jonathan D. , Hoffman Risa , Humphries Romney M. 
Published: September 2016

ABSTRACTMelioidosis is a potentially fatal infection caused by the bacteriumBurkholderia pseudomallei. Clinical diagnosis of melioidosis can be challenging since there is no pathognomonic clinical syndrome, and the organism is often misidentified by methods used routinely in clinical laboratories. Although the disease is more prevalent in Thailand and northern Australia, sporadic cases may be encountered in areas where it is not endemic, including the United States. Since the organism is considered a tier 1 select agent according to the Centers for Disease Control and Prevention and the U.S. Department of Agriculture Animal and Plant Health Inspection Service, clinical laboratories must be proficient at rapidly recognizing isolates suspicious forB. pseudomallei, be able to safely perform necessary rule-out tests, and to refer suspect isolates to Laboratory Response Network reference laboratories. In this minireview, we report a case of melioidosis encountered at our institution and discuss the laboratory challenges encountered when dealing with clinical isolates suspicious forB. pseudomalleior clinical specimens from suspected melioidosis cases.
The Respiratory Syncytial Virus Phosphoprotein, Matrix Protein, and Fusion Protein Carboxy-Terminal Domain Drive Efficient Filamentous Virus-Like Particle Formation
Authors: Meshram Chetan D. , Baviskar Pradyumna S. , Ognibene Cherie M. , Oomens Antonius G. P. 
Published: September 2016

ABSTRACT
Virus-like particles (VLPs) are attractive as a vaccine concept. For human respiratory syncytial virus (hRSV), VLP assembly is poorly understood and appears inefficient. Hence, hRSV antigens are often incorporated into foreign VLP systems to generate anti-RSV vaccine candidates. To better understand the assembly, and ultimately to enable efficient production, of authentic hRSV VLPs, we examined the associated requirements and mechanisms. In a previous analysis in HEp-2 cells, the nucleoprotein (N), phosphoprotein (P), matrix protein (M), and fusion protein (F) were required for formation of filamentous VLPs, which, similar to those of wild-type virus, were associated with the cell surface. Using fluorescence and electron microscopy combined with immunogold labeling, we examined the surfaces of transfected HEp-2 cells and further dissected the process of filamentous VLP formation. Our results show that N is not required. Coexpression of P plus M plus F, but not P plus M, M plus F, or P plus F, induced both viral protein coalescence and formation of filamentous VLPs that resembled wild-type virions. Despite suboptimal coalescence in the absence of P, the M and F proteins, when coexpressed, formed cell surface-associated filaments with abnormal morphology, appearing longer and thinner than wild-type virions. For F, only the carboxy terminus (Fstem) was required, and addition of foreign protein sequences to Fstem allowed incorporation into VLPs. Together, the data show that P, M, and the F carboxy terminus are sufficient for robust viral protein coalescence and filamentous VLP formation and suggest that M-F interaction drives viral filament formation, with P acting as a type of cofactor facilitating the process and exerting control over particle morphology.

IMPORTANCE
hRSV is responsible for >100,000 deaths in children worldwide, and a vaccine is not available. Among the potential anti-hRSV approaches are virus-like particle (VLP) vaccines, which, based on resemblance to virus or viral components, can induce protective immunity. For hRSV, few reports are available concerning authentic VLP production or testing, in large part because VLP production is inefficient and the mechanisms underlying particle assembly are poorly understood. Here, we took advantage of the cell-associated nature of RSV particles and used high-resolution microscopy analyses to examine the viral proteins required for formation of wild-type-virus-resembling VLPs, the contributions of these proteins to morphology, and the domains involved in incorporation of the antigenically important viral F protein. The results provide new insights that will facilitate future production of hRSV VLPs with defined shapes and compositions and may translate into improved manufacture of live-attenuated hRSV vaccines.