bluuebunny/crossref_metadata_2025 huggingface dataset:
Bartonella henselae infection in a dog with recalcitrant ineffective erythropoiesis
Authors: Randell Martin G. , Balakrishnan Nandhakumar , Gunn‐Christie Rebekah , Mackin Andrew , Breitschwerdt Edward B.
Published: February 2018

Ineffective erythropoiesis was diagnosed in an 8‐year‐old male castrated Labrador Retriever. Despite treatment with immunosuppressive therapy for suspected immune‐mediated erythrocyte maturation arrest, resolution of the nonregenerative anemia was not achieved. Following documentation of Bartonella henselae bacteremia by Bartonella alpha proteobacteria growth medium (BAPGM) enrichment blood culture, immunosuppressive therapy was discontinued, and the anemia resolved following prolonged antibiotic therapy. Bartonella immunofluorescent antibody testing was negative, whereas B henselae western blot was consistently positive. The contribution of B henselae bacteremia to ineffective erythropoiesis remains unknown; however, the potential role of B henselae in the pathophysiology of bone marrow dyscrasias warrants additional investigation.
Red blood cell antigen genotyping for haemoglobinopathies: considerations for thalassaemia and sickle cell disease
Authors: Chou S. T.
Published: February 2018

There are 36 blood group systems and over 300 blood group antigens. Genetic characterization of blood group antigens has demonstrated significant diversity among populations. DNA‐based red cell typing methods can offer a cost‐effective means to determine red cell antigen profiles of both patients and donors. For patients with thalassaemia and sickle‐cell disease, red cell alloimmunization remains a significant problem, particularly those who require chronic transfusion therapy. These patients often benefit from molecular red cell antigen typing to facilitate complex antibody evaluations and guide donor red cell selection. DNA‐based red cell typing can also be used to determine red cell antigen phenotypes in patients recently transfused or with interfering allo‐ or autoantibodies, to resolve discrepant serologic typing, and/or when typing antisera are not readily available. High‐resolution RH genotyping can identify variant RHD and RHCE alleles that have been associated with alloimmunization in patients with sickle‐cell disease and less commonly, thalassaemia. In the future, broader access to cost‐efficient, high‐resolution red cell genotyping technology for both patient and donor populations may be transformative for the field of transfusion medicine.
Application of tendon plating to manage failed calcaneal tendon repairs in a dog
Authors: Zellner Eric M. , Hale Michael J. , Kraus Karl H.
Published: February 2018

Objective

To report the application of a plate to treat a complicated calcaneal tendon rupture and the resulting outcome.

Study Design

Clinical case report.

Animals

A 3‐year‐old Labrador retriever.

Methods

A 3‐year‐old Labrador retriever was treated for a partially ruptured calcaneal tendon. Two primary tendon repairs with sutures and external fixation had failed. A veterinary cuttable plate was placed to internally span the tendon over the primary repair. The external fixation that had been previously placed was maintained, and the dog was placed in a non–weight‐bearing sling for 3 weeks after surgery. Adjunct therapy included an injection of platelet‐rich plasma in the tendon and laser therapy. The external fixator was removed 4 weeks postoperatively, and the plate was removed 8 weeks postoperatively.

Results

A mature fibrous union bridged the site of anastomosis 8 weeks after surgery. The owners reported normal activity 6 months after surgery and symmetric hock angles and musculature 2 years after surgery.

Conclusion

Adjunct plating of previously failed calcaneal tendon repairs in a dog resulted in an excellent long‐term outcome.

Clinical Significance

Plating tendons can be considered as an additional method that may improve tendon apposition and decrease gap formation.
Species delimitation in the morphologically conserved Coecobrya (Collembola: Entomobryidae): A case study integrating morphology and molecular traits to advance current taxonomy
Authors: Zhang Feng , Jantarit Sopark , Nilsai Areeruk , Stevens Mark I. , Ding Yinhuan , Satasook Chutamas
Published: February 2018

Traditional species delimitation only based on morphological diagnostics does not fully meet the needs of modern taxonomy. Cryptic diversity revealed by molecular evidence has been increasingly discovered in many groups; however, subsequent species description is often lacking because of inadequate taxonomy and being devoid of operational criteria. In this study, we focus on the collembolan Coecobrya which has been suspected to be a species complex living on cave guanos. Our study aimed to integrate both morphological and molecular character traits to explore this group across geographically separated cave populations. Among seven sampled populations, only minor chaetotaxic differences were detected, and between populations, there was partial overlap of discriminating characters. However, using three genes (COI, 16S and 28S), we consistently recovered across distance‐ and evolutionary model‐based molecular delimitations seven molecular lineages, corresponding to seven candidate morphospecies. A final seven‐species hypothesis was validated and seven new species were described: Coecobrya phanthuratensis sp. n., Coecobrya ranongica sp. n., Coecobrya donyoa sp. n., Coecobrya khaopaela sp. n., Coecobrya specusincola sp. n., Coecobrya khromwanaramica sp. n. and Coecobrya promdami sp. n. A tentative taxonomic workflow integrating multiple lines of evidence is proposed to facilitate the subsequent formal species description for Collembola. Unified species concept is preferable to accommodate most species concepts, delimitation criteria and data analysis methods. In practice, DNA‐based diagnoses are recommended as the standard component for the current taxonomy of Collembola, particularly within morphologically conserved groups.
An Examination of Case Studies in Management Research: A Paradigmatic Bridge
Authors: Masud Mehedi
Published: February 2018

The paper maps the value of case study in management research. In particular, it deals with the paradigmatic aspects of case study as a research strategy. In order to analyse the convergence and divergence on different dimensions of the case study research, I focus on three well-known methodology experts, namely Robert Yin, Sharan Merriam and Robert Stake. I argue that case study is a comprehensive research strategy. It has the capacity to embrace paradigm plurality representing both inductive and deductive strategies. Because of its epistemological, ontological and methodological flexibility case study has become one of the established research approaches in management. There is no fixed set of methods for the case study research. This depends on the ontological presuppositions of the researchers. The significance of the ontology becomes apparent depending on the nature of the case and the types of the research questions. As case study research is reflexive, flexible and context-specific, it allows emerging contexts to shape methods. That is why it can act as a bridge across the research paradigms. I then look at the considerable influence that the case study approach has on the management research, i.e., the role for case study in the research process. Because of its overarching role, multi-paradigmatic approach can be adopted under case study research. Case study research is, in practice a varied methodology with paradigmatic pluralism covering an array of research methods and techniques and different levels of analysis.
Umbilical cannulation optimizes circuit flows in premature lambs supported by the EXTra‐uterine Environment for Neonatal Development (EXTEND)
Authors: Hornick Matthew A. , Davey Marcus G. , Partridge Emily A. , Mejaddam Ali Y. , McGovern Patrick E. , Olive Aliza M. , Hwang Grace , Kim Jenny , Castillo Orlando , Young Kathleen , Han Jiancheng , Zhao Sheng , Connelly James T. , Dysart Kevin C. , Rychik Jack , Peranteau William H. , Flake Alan W.
Published: February 2018

Key points

Bronchopulmonary dysplasia is a disease of extreme prematurity that occurs when the immature lung is exposed to gas ventilation.

We designed a novel ‘artificial womb’ system for supporting extreme premature lambs (called EXTEND) that obviates gas ventilation by providing oxygen via a pumpless arteriovenous circuit with the lamb submerged in sterile artificial amniotic fluid.

In the present study, we compare different arteriovenous cannulation strategies on EXTEND, including carotid artery/jugular vein (CA/JV), carotid artery/umbilical vein (CA/UV) and umbilical artery/umbilical vein (UA/UV).

Compared to CA/JV and CA/UV cannulation, UA/UV cannulation provided significantly higher, physiological blood flows to the oxygenator, minimized flow interruptions and supported significantly longer circuit runs (up to 4 weeks).

Physiological circuit blood flow in UA/UV lambs made possible normal levels of oxygen delivery, which is a critical step toward the clinical application of artificial womb technology.

EXTEND (EXTra‐uterine Environment for Neonatal Development) is a novel system that promotes physiological development by maintaining the premature lamb in a sterile fluid environment and providing gas exchange via a pumpless arteriovenous oxygenator circuit. During the development of EXTEND, different cannulation strategies evolved with the aim of improving circuit flow. The present study examines how different cannulation strategies affect EXTEND circuit haemodynamics in extreme premature lambs. Seventeen premature lambs were cannulated at gestational ages 105–117 days (term 145–150 days) and supported on EXTEND for up to 4 weeks. Experimental groups were distinguished by cannulation strategy: carotid artery outflow and jugular vein inflow (CA/JV; n = 4), carotid artery outflow and umbilical vein inflow (CA/UV; n = 5) and double umbilical artery outflow and umbilical vein inflow (UA/UV; n = 8). Circuit flows and pressures were measured continuously. As we transitioned from CA/JV to CA/UV to UA/UV cannulation, mean duration of circuit run and weight‐adjusted circuit flows increased (P < 0.001) and the frequency of flow interruptions declined (P < 0.05). Umbilical vessels generally accommodated larger‐bore cannulas, and cannula calibre was directly correlated with circuit pressures and indirectly correlated with flow:pressure ratio (a measure of post‐membrane resistance). We conclude that UA/UV cannulation in fetal lambs on EXTEND optimizes circuit flow dynamics and flow stability and also supports circuit flows that closely approximate normal placental flow.
Asymptotic Approximations to the Isothermal Pyrolysis of Deodara Leaves using Gamma Distribution
Authors: Dhaundiyal Alok , Singh Suraj
Published: February 2018

The main aim of th is paper pivote d ar ound th e influence of some parameters relev ant to biomass pyrolys is on the numerical solutions of the nth order distributed activation energy model (DAEM) using the Gamma distribution. The upper limit of ‘dE’ integral, frequency factor, reaction order, and the shape and rate parameters of the Gamma distribution are investigated. Analys is of the mathematical model is done with the help of asymptotic expansion.
Effects of Effusion and Film Cooling Jet Momenta on Combustor Flow Fields
Authors: Briones Alejandro M. , Stouffer Scott D. , Vogiatzis Konstantinos , Rein Keith , Rankin Brent A.
Published: February 2018

The effects of effusion and film cooling momenta on combustor flow fields are investigated. Steady, compressible three-dimensional (3D) simulations are performed on a single-swirler combustor using Reynolds-averaged Navier–Stokes (RANS) with flamelet generated manifold and Lagrangian–Eulerian multiphase spray, while accounting for dome and liner cooling. Two simulations are performed on the same mesh. One simulation is conducted using a parallelized, automated, predictive, imprint cooling (PAPRICO) model with dynamic flux boundary conditions and downstream pressure probing (DFBC-DPP). PAPRICO involves removing the cooling jet geometry from the dome and liner while retaining the cooling hole imprints. The PAPRICO model does not require a priori knowledge of the cooling flow rates through various combustor liner regions nor specific mesh partitioning. The other simulation is conducted using the homogenously patched cooling (HPC) model, which involves removing all the cooling jets. The HPC model applies volumetric sources adjacent to the combustor wall regions where cooling jets are present. The momentum source, however, becomes negligible. The HPC model is not predictive and requires tedious ex situ mass flow measurements from an auxiliary flowbench experiment, afflicted with systematic errors. Hence, the actual in situ air flow splits through the several combustor regions is not known with absolute certainty. The numerical results are compared with measurements of mass flow rates, static pressure drops, and path-integrated temperatures. The results demonstrate that it is critical to account for the discrete dome and liner cooling momentum to better emulate the reacting flow in a combustor.
Complex Flow Generation and Development in a Full-Scale Turbofan Inlet
Authors: Guimarães Tamara , Todd Lowe K. , O'Brien Walter F.
Published: February 2018

The future of aviation relies on the integration of airframe and propulsion systems to improve aerodynamic performance and efficiency of aircraft, bringing design challenges, such as the ingestion of nonuniform flows by turbofan engines. In this work, we describe the behavior of a complex distorted inflow in a full-scale engine rig. The distortion, as in engines on a hybrid wing body (HWB) type of aircraft, is generated by a 21-in diameter StreamVane, an array of vanes that produce prescribed secondary flow distributions. Data are acquired using stereoscopic particle image velocimetry (PIV) at three measurement planes along the inlet of the research engine (Reynolds number of 2.4 × 106). A vortex dynamics-based model, named StreamFlow, is used to predict the mean secondary flow development based on the experimental data. The mean velocity profiles show that, as flow develops axially, the vortex present in the profile migrates clockwise, opposite to the rotation of the fan, and toward the spinner of the engine. The turbulent stresses indicate that the center of the vortex meanders around a preferred location, which tightens as flow gets closer to the fan, yielding a smaller radius mean vortex near the fan. Signature features of the distortion device are observed in the velocity gradients, showing the wakes generated by the distortion screen vanes in the flow. The results obtained shed light onto the aerodynamics of swirling flows representative of distorted turbofan inlets, while further advancing the understanding of the complex vane technology presented herein for advanced ground testing.
EBFOG: Deposition, Erosion, and Detachment on High-Pressure Turbine Vanes
Authors: Casari Nicola , Pinelli Michele , Suman Alessio , di Mare Luca , Montomoli Francesco
Published: February 2018

Fouling and erosion are two pressing problems that severely affect gas turbine performance and life. When aircraft fly through a volcanic ash cloud, the two phenomena occur simultaneously in the cold as well as in the hot section of the engine. In the high-pressure turbine (HPT), in particular, particles soften or melt due to the high gas temperatures and stick to the wet surfaces. The throat area, and hence the capacity, of the HPT is modified by these phenomena, affecting the engine stability and possibly forcing engine shutdown. This work presents a model for deposition and erosion in gas turbines and its implementation in a three-dimensional Navier–Stokes solver. Both deposition and erosion are taken into account, together with deposit detachment due to changed flow conditions. The model is based on a statistical description of the behavior of softened particles. The particles can stick to the surface or can bounce away, eroding the material. The sticking prediction relies on the authors' Energy Based FOulinG (EBFOG) model. The impinging particles which do not stick to the surface are responsible for the removal of material. The model is demonstrated on a HPT vane. The airfoil shape evolution over the exposure time as a consequence of the impinging particles has been carefully monitored. The variation of the flow field as a consequence of the geometrical changes is reported as an important piece of on-board information for the flight crew.
Position and Force Switching Control for Gear Engagement of Automated Manual Transmission Gear-Shift Process
Authors: Wang Xiangyu , Li Liang , He Kai , Liu Yahui , Liu Congzhi
Published: February 2018

Gear-shift control is essential in automated manual transmission (AMT) systems, because it has a significant influence on comfort of vehicle and lifespan of AMT. Gear engagement process is the most important part of gear-shift process, and it has multistage and nonlinear characteristics, which make it difficult to realize smooth and fast control. This paper proposes a position and force switching control scheme for gear engagement. At the beginning and the end of gear engagement process, the combination sleeve is supposed to reach the desired position quickly with a small resistance for which a position controller is designed by using sliding mode control (SMC) method. A force controller is designed for the midsynchronizing stage, because the combination sleeve is blocked at this stage until the synchronization is finished. Simulations and experiments are carried out to show that gear-shift quality is improved and gear-shift shock is reduced greatly by the proposed method.
Development of Hierarchical Control Logic for Two-Channel Hydraulic Active Roll Control System
Authors: Pi Dawei , Wang Xianhui , Wang Hongliang , Kong Zhenxing
Published: February 2018

In this paper, a hierarchical control logic for two-channel hydraulic active roll control (ARC) system, which includes vehicle level control and actuator level control is proposed. Vehicle level control consists of antiroll torque controller and antiroll torque distributor. The antiroll torque controller is designed with “PID + feedforward” algorithm to calculate the total antiroll moment. The antiroll torque distributor is devised based on fuzzy control method to implement an antiroll moment allocation between the front and rear stabilizer bar. Actuator level control is designed based on pressure and displacement, respectively. The contrastive analysis of the two proposed actuator control method is presented. The hardware-in-the-loop (HIL) test platform is proposed to evaluate the performance of the devised control algorithm. The HIL simulation result illustrates that actuator displacement control could generate a relatively accurate antiroll moment, and the vehicle roll stability, yaw stability can be enhanced by the proposed ARC control method.
Bridge Deck Flutter Control Using Winglets and Static Output Feedback
Authors: Bera K. K. , Chandiramani N. K.
Published: February 2018

Control of wind-induced flutter of a bridge deck is studied using static output feedback. Servomotor-actuated winglets provide the control forces. Deck and winglets are modeled as flat plates and their aerodynamic interaction is neglected. Self-excited wind forces acting on deck and winglets are modeled using the Scanlan–Tomko model, with flat plate flutter derivatives (FDs) obtained from Theodorsen functions. Rogers rational function approximation (RFA) is used for time domain representation of wind forces in order to simplify the stability and control analyses. Control input to servomotors is based on direct feedback of vertical and torsional displacements of deck. Feedback gains that are constant, or varying with wind speed, are considered. Winglet rotations being restricted, flutter and divergence behavior is studied using system eigenvalues as well as responses. Results show that variable gain output feedback (VGOF) control using servomotor driven winglets is very effective. It provides the maximum increase in critical speed and maximum attenuation of response, followed by control with gain scheduling, with the former requiring less input power. Control with constant gain is least effective. Control of deck rotation generally appears to improve with wind speed.
Toward the Effect of Dependent Distribution Parameters on Reliability Prediction
Authors: Cheng Yao , Du Xiaoping
Published: February 2018

Random variables are commonly encountered in engineering applications, and their distributions are required for analysis and design, especially for reliability prediction during the design process. Distribution parameters are usually estimated using samples. In many applications, samples are in the form of intervals, and the estimated distribution parameters will also be in intervals. Traditional reliability methodologies assume independent interval distribution parameters, but as shown in this study, the parameters are actually dependent since they are estimated from the same set of samples. This study investigates the effect of the dependence of distribution parameters on the accuracy of reliability analysis results. The major approach is numerical simulation and optimization. This study demonstrates that the independent distribution parameter assumption makes the estimated reliability bounds wider than the true bounds. The reason is that the actual combination of the distribution parameters may not include the entire box-type domain assumed by the independent interval parameter assumption. The results of this study not only reveal the cause of the imprecision of the independent distribution parameter assumption, but also demonstrate a need of developing new reliability methods to accommodate dependent distribution parameters.
Learning From the Past: Uncovering Design Process Models Using an Enriched Process Mining
Authors: Lan Lijun , Liu Ying , Feng Lu Wen
Published: February 2018

Design documents and design project footprints accumulated by corporate information technology systems have increasingly become valuable sources of evidence for design information and knowledge management. Identification and extraction of such embedded information and knowledge into a clear and usable format will greatly accelerate continuous learning from past design efforts for competitive product innovation and efficient design process management in future design projects. Most of the existing design information extraction systems focus on either organizing design documents for efficient retrieval or extracting relevant product information for product optimization. Different from traditional systems, this paper proposes a methodology of learning and extracting useful knowledge using past design project documents from design process perspective based on process mining techniques. Particularly different from conventional techniques that deal with timestamps or event logs only, a new process mining approach that is able to directly process textual data is proposed at the first stage of the proposed methodology. The outcome is a hierarchical process model that reveals the actual design process hidden behind a large amount of design documents and enables the connection of various design information from different perspectives. At the second stage, the discovered process model is analyzed to extract multifaceted knowledge patterns by applying a number of statistical analysis methods. The outcomes range from task dependency study from workflow analysis, identification of irregular task execution from performance analysis, cooperation pattern discovery from social net analysis to evaluation of personal contribution based on role analysis. Relying on the knowledge patterns extracted, lessons and best practices can be uncovered which offer great support to decision makers in managing any future design initiatives. The proposed methodology was tested using an email dataset from a university-hosted multiyear multidisciplinary design project.
Magnetic Chest Tube Positioning System
Authors: Laan Danuel , Diem Vu Trang Ngoc , Hernandez Matthew , Schiller Henry
Published: February 2018

Tube thoracostomy (TT) insertion can serve as a life-saving adjunct for thoracic trauma. Unfortunately, suboptimal positioning using the open, standard of care technique is associated with complications resulting in impaired TT function. Using a porcine model, we aimed to determine whether a magnetic chest tube positioning system (MCTPS) could be utilized to direct the intrathoracic TT position. Using recently deceased cross-bred domestic swine, we performed TT using our MCTPS and the standard of care open technique. The operator held one magnet outside of the thorax. The second magnet was positioned at the distal aspect of the TT. The operator was tasked with positioning the TT to distinct premarked intra-thoracic locations under blinded conditions. The experiment was video-recorded through an open sternotomy incision. As a control, TT was inserted using the standard of care open technique. The utilization of MCTPS successfully directed TT from one premarked location to another in 4 of 5 attempts (80%). Conversely, the control TT without magnetic guidance failed to navigate the premarked intra-thoracic locations with 0 of 5 attempts successful (p = 0.05). Positional flaws after TT placement are common. We demonstrate the feasibility of the MCTPS as an alternative to traditional hand-guided technique under simulated TT insertion conditions. The MCTPS is possibly superior to the current standard of care technique of TT. Additional studies are needed to develop this emerging technology in humans.
Flow Field Investigation in a Partial Admission Supersonic Turbine of LOX Booster Turbopump for Staged Combustion Cycle Based Rocket Engine
Authors: Mishra Arpit , Ghosh Parthasarathi
Published: February 2018

To obtain high specific work output with small mass flow rate, high-pressure ratios across the turbines are required in liquid rocket engine turbopumps. An impulse-type supersonic turbine can achieve this. To prevent losses due to low blade aspect ratio and issues related to manufacturing and industrial problems, partial admission configuration is adopted. Partial entry in a turbine is achieved by adjusting the extent of the nozzle arc of admission, leading to a strong unsteady circumferential asymmetry of flow parameters in the rotor passage, and degradation in efficiency. The pressing need of aerodynamic design of supersonic partial admission turbines to improve their efficiency demands an investigation of the viscous fluid dynamic of the turbine flow field. This work reports the aerothermodynamic steady state CFD analysis to obtain the performance parameters of a three-dimensional partial admission turbine for LOX booster turbopump in a semicryogenic engine using ANSYS® CFX. The areas of steady loss have been identified through entropy generation contours, and the effects associated with aerodynamic loss structures like secondary flow, shock location, recirculation with additional pumping and mixing losses have been investigated for designed operating condition corresponding to 100% nominal thrust.
A Study on Tribological Behavior of Linz-Donawitz Slag Filled Polypropylene Composites Using Experimental Design and Neural Networks
Authors: Pati Pravat Ranjan , Satapathy Alok
Published: February 2018

Short fiber-reinforced polymer composites are used in numerous tribological applications. In the present work, an attempt has been made to improve the wear resistance of short glass fiber (SGF) reinforced polypropylene composites by incorporation of micro-sized Linz-Donawitz slag (LDS) particles. Composites with different LDS content (0, 7.5, 15 and 22.5 wt%) in a polypropylene matrix base with 20 wt% SGF reinforcement are prepared by injection molding technique. Solid particle erosion trials, as per ASTM G76 test standards, are conducted on the composite samples following a well-planned experimental schedule based on Taguchi design-of-experiments. Significant process parameters predominantly influencing the rate of erosion are identified. The study reveals that the LDS content and impact velocity are the most significant among various factors influencing the wear rate of these composites. Further, a prediction model based on artificial neural network (ANN) is proposed to predict the erosion performance of the composites under a wide range of erosive wear conditions. This work shows that an ANN model is quite helpful in saving time and resources that are required for a large number of experimental trials and thus, successfully predicts the erosion rate of composites both within and beyond the experimental domain.
Interaction Between Unbalance and Misalignment Responses in Flexibly Coupled Rotor Systems Integrated With AMB
Authors: Siva Srinivas Rangavajhala , Tiwari Rajiv , Babu Ch. Kanna
Published: February 2018

This paper studies the rotor dynamic behavior of misaligned-coupled rotor systems integrated with active magnetic bearings. The simplest possible numerical model has been derived with a 4-degree of freedom two coupled Jeffcott rotor systems. The effect of flexible coupling on the interaction between the response due to unbalance and misalignment has been studied. To demonstrate the influence three cases have been considered a) pure misalignment b) pure unbalance c) presence of both unbalance and misalignment. This is an original attempt considering the standard practice of using beam element based finite element modeling techniques for such systems. To simplify the problem, the weight dominance of discs has been assumed. Also the coupling considered in the problem is of flexible type. Misalignment in coupled rotors has been reported in literature to produce all harmonics both odd and even (...−2, −1, 0, 1, 2...) on either side of full spectrum. A suitable coupling excitation function has been chosen so that the response yields all the harmonics in spectrum. The numerical simulation has been performed in MATLAB/SIMULINK™ to generate the responses in time domain. Though AMB is incorporated in the system for vibration attenuation, the emphasis of the present paper shall be to demonstrate the interplay between unbalance and misalignment in flexibly coupled rotor systems.
Computational Study of Film Cooling With Mist and Air for a Flat Plate
Authors: Pabbi Setty Mallikarjuna Rao , Biswal Pratibha , Prasad Bhamidi
Published: February 2018

The inlet air temperature of turbines are significantly high which may result in the damage of the blade material. As a consequence, it is required to cool the turbine blades and a number of cooling techniques are introduced in the past. The cooling technique involving evaporation of water droplets is the motivation and focus of this work. When the water droplets are injected along with the dry air, the existing concentration difference between the water droplets and dry air results in the evaporation leading in the drop of the coolant temperature. This phenomena does not occur when the coolant is dry air and this part is addressed for the first time in this study. The cooling performance is investigated on wall of straight channel in the presence of a film cooling hole. Dry air along with water droplets are supplied through the film cooling hole and the computations are carried out for different droplet diameters and mist concentrations. Results showed that, the overall cooling effectiveness is always larger for the mist-air case compared to that for the dry air case. Also, the cooling effectiveness increases with the percentage of mist in the mist-air system for a specific droplet diameter. At a specific mass flow rate and specific mist percentage, the increase in droplet diameter results in the decrease of cooling effectiveness.
Aerodynamic Performance of an Elliptical-Bladed Savonius Rotor Under the Influence of Number of Blades and Shaft
Authors: Alom Nur , Kumar Nitish , Saha Ujjwal K.
Published: February 2018

In the past, various influencing parameters of the conventional semicircular-bladed Savonius rotor such as overlap ratio, aspect ratio, number of rotor blades have been optimized through numerical and experimental investigations to improve its performance. Furthermore, the rotor performance under the influence of various blade profiles, shaft, endplates, and augmentation techniques has also been studied. Recent rudimentary studies with an elliptical-bladed Savonius rotor have demonstrated its potential to harness the wind energy more efficiently; however, its influencing parameters have not been thoroughly studied and therefore they need to be optimized to arrive at a suitable design configuration. In view of this, the objective of the present investigation is to optimize the number of elliptical blades on the rotor and then to find the influence of shaft with the optimized number of blades on the rotor performance. For this, 2D unsteady simulation is carried out with different combinations of blades, and after having optimized the number of blades, the influence of shaft on the rotor performance is studied. The continuity, unsteady Reynolds-Averaged Navier-Stokes (RANS) equations, and two equation eddy viscosity SST (Shear Stress transport) k-ω model are solved by using the commercial FVM based solver ANSYS Fluent. The torque and power coefficients are calculated as a function of tip speed ratio (TSR) and at rotating conditions. The total pressure, velocity magnitude, turbulence intensity and streamline patterns are obtained and analyzed to arrive at the intended objective. The numerical investigation demonstrates an improved flow characteristics and performance coefficients of the 2-elliptical-bladed profile without shaft.
Flow and Heat Transfer Analysis of Mist-Film Cooling on a Flat Plate
Authors: Dwivedi Anjali , Verma Ankit , Sarkar S.
Published: February 2018

Film cooling is one of the preferred methods for effective cooling of a gas turbine that forms a protective layer between hot flue gases and blade surface. This paper investigates the interaction of mist in the secondary flow and physics indicating the upper limit of mist concentration. Numerical simulations are performed on a flat plate having a series of discrete holes with 35 degree streamwise orientation and the holes are connected to a common delivery plenum chamber. The blowing ratio, density ratio and Reynolds number based on freestream and hole diameter (D) are 0.5, 1.2 and 15885 respectively. A two-phase mist consisting of finely dispersed water droplets of 10 micron in an airstream is introduced as the coolant from these holes. The latent heat absorbed by the evaporating droplets significantly reduces the sensible heat of the main stream, providing heat sinks that result in enhanced cooling effectiveness. The coupling between the two-phases is modelled through the interaction terms in the transport equations. Computations are performed by ANSYS Fluent 15.0 using k-ε realizable model.

The results illustrate insight of complex transport phenomena associated with the mist of varying concentration from 2% to 7%. It has been observed that the maximum enhancement of cooling effectiveness reaches 43% at X/D = 10 for 2% mist by mass with an average enhancement of 26.5%. For 3% mist, the maximum enhancement becomes 80% at X/D = 16 with the average cooling enhancement of 43%. Mist concentrations 5% and beyond trend to increase average cooling because of more absorption of latent heat by droplets, but its trajectories shift towards wall, detrimental to the blade due to corrosion effect and thermal stresses.
In-Situ Experiments to Estimate the Performance Characteristics of a Double-Step Helical-Bladed Hydrokinetic Turbine
Authors: Talukdar Parag K. , Kulkarni Vinayak , Das Amarendra K. , Dwivedy Santosha K. , Kakoty Sashindra Kumar , Mahanta Pinakeswar , Saha Ujjwal K.
Published: February 2018

With the rising level of greenhouse gas emissions and fuel prices, the hydrokinetic turbines have become increasingly popular for electricity generation in rural and remote areas teemed with small river streams. Such lift-based helical-bladed hydrokinetic turbines were invented over a decade ago, however, they could not find their wide application in commercial power generation. The present investigation deals with the in-situ experiments of a double-step three-bladed helical hydrokinetic turbine for possible electricity generation. Further, its performance is compared with that of a conventional single-step helical-bladed turbine. The main parameters that influence the performance of a helical-bladed hydro turbine are solidity ratio, blade wrap ratio, helix angle, blade profile and number of blades. In the present work, the helical NACA 0022 bladed turbines with solidity ratio of 0.20 and blade wrap ratio of 1.0 have been developed. The developed single and double-step configurations have been field-tested in the Brahmaputra river and their performance characteristics are estimated at different mechanical loading conditions using mechanical dynamometer.
Experimental Investigation of Low Emission Liquid Fuelled Reverse Cross Flow Combustor
Authors: Sharma Preetam , Arghode Vaibhav
Published: February 2018

This study deals with an experimental investigation of a low emission liquid fuelled (ethanol) reverse cross-flow combustor. This investigation is carried out to cater to the need of burning liquid fuels (including alternative fuels) with minimum emissions in gas turbine engines used for both aircraft and land based power generation applications using modern combustion technologies. In the present combustor design, the air inlet and the exhaust ports are located on the same side (and hence the name reverse-flow) whereas the liquid fuel is injected directly into the strong cross-flow of the air using a small diameter round tube to aid fuel atomization. Hence, a conventional atomization system is absent in the investigated combustor. The reverse-flow configuration allows effective internal product gas recirculation to facilitate the preheating and dilution of the oxidizer stream and stabilization of a distributed reaction zone. This apparently suppresses near stoichiometric reactions and hot spot regions resulting in low pollutant (NOx and CO) emissions. In the present case, the heat load is varied (keeping a constant air flow rate) from 3.125 kW to 6.25 kW which results in the thermal intensity variation from 19 MW/m3-atm to 39 MW/m3-atm. Two different tubes with internal diameters (dfuel) of 0.5 mm and 0.8 mm are used for injection of liquid fuel into the cross flow of air. The combustor was also tested in premixed-prevaporized (PP) mode with ethanol for benchmarking. The combustion process was found to be stable with NOx emissions of 1.6 ppm (premixed-prevaporized), 8 ppm (dfuel = 0.5 mm), 9 ppm (dfuel = 0.8 mm). The CO emissions were 5 ppm (premixed-prevaporized), ∼100 ppm (dfuel = 0.5, 0.8 mm), at atmospheric pressure operation (corrected to 15% O2) and ϕ = 0.7, Tadiabatic ∼1830 K. Reaction zone positioning inside the combustor was investigated using OH* chemiluminescence imaging and global flame pictures, and the same was found to be located in the vicinity of the air jet.
Force Estimation in Electromagnetic System Using Augmented Kalman Filter
Authors: Redekar Rahul Vijaykumar , Kumar Gaurav , Kalita Karuna , Tammi Kari
Published: February 2018

The analytical modelling and real time estimation of electromagnetic forces brings many challenges and in many situations, it is very difficult to develop an accurate model of force production. The present work describes an estimation of the actual forces generated by an electromagnetic actuator based on augmented Kalman filter.

A cantilever beam with end concentrated mass has been chosen as a vibrating system and an E–shaped laminated core with coils on the middle limb has been chosen as the electromagnetic exciter. The available analytical formulation has been chosen for the calculation of the generated forces which have been corrected using augmented Kalman filter.

The developed experimental setup has a mild steel beam of 150 mm length with a mass of 560 g at its tip and an E shaped lamination core with a stack thickness of 38 mm.
CFD Studies on the Performance of a Centrifugal Compressor With Single Wall Rotating Vaneless Diffusers at the Wall Extension Ratios of 1.1 and 1.15
Authors: Konakala Srinivasa Rao , Govardhan Mukka
Published: February 2018

Efficiency of the centrifugal compressor is affected by non-uniform flow at the exit of the impeller and the losses in the diffuser. This causes a significant loss of total pressure and drop in the performance of a centrifugal compressor. By rotating some portion of stationary vaneless diffuser walls with the speed of the impeller, the shear forces between the flow and diffuser walls are greatly reduced. Thereby improvement in the operating range and performance is achieved. This paper presents CFD studies on the effect of different single wall rotations i.e. hub rotation and shroud rotation of the vaneless diffusers on the overall performance at 10% and 15% extension of impeller walls. It is observed that the performance characteristics of compressors with all RVD models offer higher static pressure recovery and also higher rate of diffusion compared to the base compressor with SVD. It is clear that as extended radius increases from 10% to 15%, substantial improvement of efficiency and reduction of losses are observed for both type of models. Out of two single wall rotation models, SRVD model is able to better mix the jet-wake type of impeller exit flows and minimizes the losses therein and improve the performance of the centrifugal compressor.
Prediction of Gas Turbine Afterburner Performance Using CFD for Different Operating Conditions and Reheat Strength
Authors: Kattegollahalli Shivakumar Darshan , Sabbani Ganesan , Singh Gursharanjit , Harthi Revanasiddappa Purushothama
Published: February 2018

A gas turbine afterburner is required to operate under severe conditions of pressure and temperature to meet the design requirements of next generation gas turbine engines. This fact, coupled with the current trends towards higher turbine discharge temperature and the requirement for satisfactory operation over extended fuel/air ratios and flight maps call for greater understanding of the internal aerodynamics for improving thrust developed by the afterburner. The present work focuses on prediction of performance of a practical afterburner for different altitude conditions and reheat strengths (i.e., fuel-air ratios) using Computational Fluid Dynamics (CFD) simulations. Combustion efficiency and thrust boost at these conditions have been predicted. The reacting flow field has been analyzed and changes suggested for improving thrust at low performance points.
Optimization of Electrical Discharge Coating Process Using MOORA Based Firefly Algorithm
Authors: Sahu Anshuman Kumar , Mahapatra Siba Sankar , Chatterjee Suman
Published: February 2018

Electrical discharge machining (EDM), a thermo-mechanical machining process, is used in producing a complicated intrinsic cavity in difficult-to-machine materials with excellent surface finish. One of the major disadvantages of EDM process is the tool wear. However, tool wear can be used advantageously for coating purpose. Coating is a unique method of EDM process by the use of electrode prepared through powder metallurgy (PM) route. This process is also cheaper as compared to other deposition processes like chemical vapor deposition (CVD) and physical vapor deposition (PVD) processes. Therefore, electrical discharge coating (EDC) can be employed in industries for coating purpose where the corrosion resistance and hardness of the work piece material are required to be increased for their use in a wide range of environmental condition. Copper (Cu) and tungsten (W) powders in weight percentage of 30 and 70 respectively are used for the preparation of the tool electrode. The PM process parameters like compaction pressure (CP) and sintering temperature (ST) are varied to prepare the tool electrodes. The density and electrical conductivity of the electrodes are found to increase with an increase in compaction pressure and sintering temperature. The substrate on which coating is made is chosen as AISI 1040 stainless steel with EDM oil as the dielectric fluid. During coating, the influence of parameters like discharge current (Ip), duty cycle (τ) and pulse-on-time (Ton) on material deposition ratio (MDR), Average surface roughness (Ra), coated layer thickness (LT) and micro-hardness of the coated layer are studied. To reduce the number of the experiment, Taguchi’s L18 orthogonal array has been used. To find out the best parametric combination that can simultaneously optimize all performance measures, multi-objective optimization on the basis of ratio analysis (MOORA) method combined with Firefly algorithm has been employed.
Parametric Studies of Vortex Generators Using Source Term Modelling
Authors: Kumar Kanneri Thettiyepath Arun , Madsen Jesper , Piragalathalwar Sudhakar , Narayana Aswatha
Published: February 2018

The Vortex Generators located over the airfoils are generally small in size. Due to its small size and shape, the mesh requirements are high and mesh generation becomes complex. In this study, the source term modelling approach termed as BAY model developed by Bender et al. is used to simulate the effect of Vortex Generators. One of the advantages of BAY model is its simplicity eliminating the complex grid requirements around the Vortex Generator for the Computational Fluid Dynamic simulations. Comparing with the BAY model approach, mesh resolved Vortex Generator approach will need more number of cells in the domain. Hence using the B AY model is advantageous in computational cost also.

The solver EllipSys3D, which is an incompressible structured multi-block finite volume based RANS (Reynolds Averaged Navier-Stokes) solver, is used for the studies. Parametric studies using BAY model are carried out for different heights, lengths, chord wise locations and spacing of Vortex Generators on a wind turbine airfoil. The qualitative results predicted using BAY model are in lined with experimental results from literature showing that it is capable to mimic the effect of Vortex Generators. So overall due to its simplicity source term modelling through BAY model can be used for quick parametric studies.
A Variable Viscosity Approach for the Analysis of Steady State and Dynamic Characteristics of Two-Lobe Journal Bearing With TiO2 Based Nanolubricant
Authors: Kumar Ashutosh , Kakoty Sashindra Kumar
Published: February 2018

Steady-state and dynamic characteristics of two-lobe journal bearing, operating on TiO2 based Nano-lubricant has been obtained. The effective viscosity is obtained by using Krieger-Dougherty viscosity model for a given volume fraction of nanoparticle in the base fluid. Various bearing performance characteristics are then obtained by solving modified Reynolds equation for variable viscosity model and couple stress model. The stiffness and damping coefficients are also determined for various values of the volume fraction of the nanoparticle in the nanofluid. Results reveal that load carrying capacity and flow coefficient increase whereas friction variable decreases without affecting the stability condition of two-lobe journal bearing operating on TiO2 based nanolubricant. On the other hand attitude angle and dynamic coefficients remains constant for all the values of volume fraction of nanoparticle.