ORCID Profile
0000-0003-0110-3135
Current Organisation
RMIT University
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Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.MSEC.2019.04.017
Abstract: Despite the tremendous acceptance of additively manufactured (AM) Titanium alloys (Ti6Al4V) in the field of biomedical engineering, the high surface roughness due to partially-melted particles (fabricated in selective laser melting (SLM) process), limits their uses as hip implants. The objective of this study, therefore, is to modify the SLM fabricated Ti6Al4V implant interfaces with 2-Methacryloyloxyethyl phosphorylcholine (MPC) polymer, in the hope of enhancing surface properties and preventing the attachment of the cell simultaneously without affecting the mechanical properties significantly. Three different monomer concentrations were examined to determine the influence of monomer concentrations on polymerisation rate, chain length, and surface properties of the implants. S les grafted with 0.6 M monomer concentration showed more uniform surface and less surface roughness in comparison with other s les and untreated Ti6Al4V surfaces. 0.6 M monomer concentration was found to be the best option for grafting PMPC to the hip implant interfaces because of its improved surface morphology, surface roughness, polymerisation rate, penetration depth and hardness results. Moreover, cell study on optimal surfaces revealed that PMPC grafted surfaces prevent the implant interfaces from uncontrollable cell attachment which is of utmost importance in smoothing the motion of the hip implant under cyclic loading. Overall, the PMPC grafting demonstrated the potentiality of its application on SLM Ti6Al4V substrate for improved hip arthroplasty performance.
Publisher: ASMEDC
Date: 2002
Abstract: This is Part I of a two-part paper describing a new compressor volute design system, which is applied to an interactive program that completely describes volute geometry and its interactions with CFD. Part I goes into the theory behind the program and the design of the volute geometry by application of Bezier polynomials while Part II fully describes the actual design system approach and its application to the program. Based on the developed mathematics of B-spline and Bezier polynomials, the present paper further develops the extent of Bezier polynomials by application of Bezier to volute design. Bezier polynomials will be used to describe and define volute geometry for centrifugal compressors with the objective of serving as an aid for volute design and performance analysis. The current research aims to develop an algorithm for volute design that will enable the volute geometry, to be fully described and viewed, in two-dimensional (2D) and three-dimensional (3D) modes. A program based on this algorithm will deliver output data for grid generation and CFD flow simulation and eventual manufacture of the volute. These procedures will be developed for a family of centrifugal compressors.
Publisher: SAE International
Date: 20-11-2013
DOI: 10.4271/2013-01-9121
Publisher: Elsevier BV
Date: 2012
Publisher: American Society of Mechanical Engineers
Date: 26-06-2017
DOI: 10.1115/GT2017-64795
Abstract: The Dry-Low-NOx (DLN) Micromix combustion technology has been developed originally as a low emission alternative for industrial gas turbine combustors fueled with hydrogen. Currently the ongoing research process targets flexible fuel operation with hydrogen and syngas fuel. The non-premixed combustion process features jet-in-crossflow-mixing of fuel and oxidizer and combustion through multiple miniaturized flames. The miniaturization of the flames leads to a significant reduction of NOx emissions due to the very short residence time of reactants in the flame. The paper presents the results of a numerical and experimental combustor test c aign. It is conducted as part of an integration study for a dual-fuel (H2 and H2/CO 90/10 Vol.%) Micromix combustion chamber prototype for application under full scale, pressurized gas turbine conditions in the auxiliary power unit Honeywell Garrett GTCP 36-300. In the presented experimental studies, the integration-optimized dual-fuel Micromix combustor geometry is tested at atmospheric pressure over a range of gas turbine operating conditions with hydrogen and syngas fuel. The experimental investigations are supported by numerical combustion and flow simulations. For validation, the results of experimental exhaust gas analyses are applied. Despite the significantly differing fuel characteristics between pure hydrogen and hydrogen-rich syngas the evaluated dual-fuel Micromix prototype shows a significant low NOx performance and high combustion efficiency. The combustor features an increased energy density that benefits manufacturing complexity and costs.
Publisher: Informa UK Limited
Date: 25-11-2016
Publisher: ASME International
Date: 23-10-2018
DOI: 10.1115/1.4041495
Abstract: The dry-low-NOx (DLN) micromix combustion technology has been developed originally as a low emission alternative for industrial gas turbine combustors fueled with hydrogen. Currently, the ongoing research process targets flexible fuel operation with hydrogen and syngas fuel. The nonpremixed combustion process features jet-in-crossflow-mixing of fuel and oxidizer and combustion through multiple miniaturized flames. The miniaturization of the flames leads to a significant reduction of NOx emissions due to the very short residence time of reactants in the flame. The paper presents the results of a numerical and experimental combustor test c aign. It is conducted as part of an integration study for a dual-fuel (H2 and H2/CO 90/10 vol %) micromix (MMX) combustion chamber prototype for application under full scale, pressurized gas turbine conditions in the auxiliary power unit Honeywell Garrett GTCP 36-300. In the presented experimental studies, the integration-optimized dual-fuel MMX combustor geometry is tested at atmospheric pressure over a range of gas turbine operating conditions with hydrogen and syngas fuel. The experimental investigations are supported by numerical combustion and flow simulations. For validation, the results of experimental exhaust gas analyses are applied. Despite the significantly differing fuel characteristics between pure hydrogen and hydrogen-rich syngas, the evaluated dual-fuel MMX prototype shows a significant low NOx performance and high combustion efficiency. The combustor features an increased energy density that benefits manufacturing complexity and costs.
Publisher: SAE International
Date: 04-2014
DOI: 10.4271/2014-01-0648
Publisher: ASMEDC
Date: 2002
Abstract: This paper examines the impact on the power generation capacity of a wind turbine as a result of the modification of the shape of the blades of an existing wind turbine. The modification involves curving the blades in the direction of rotation resulting in an increase in generated lift and therefore an increase in the power output of the wind turbine. Two three-bladed models were tested in a wind tunnel, one original straight-bladed model and one modified model both of which were 0.84 m in diameter. A study of the methods of flow visualization for a wind turbine in a wind tunnel was investigated. The corresponding results are presented. It was discovered that the china clay method of flow visualization in conjunction with a strobe light gave a good indication of the direction of the airflow over the turbine blades as did condensed oil droplets from a smoke wand which presented a very clear indication of the span-wise flow. It was concluded from the investigation that curving the blade into the direction of rotation on a wind turbine produced a greater power output at the same wind speed as an unmodified wind turbine.
Publisher: Informa UK Limited
Date: 10-12-2017
Publisher: SAE International
Date: 04-2014
DOI: 10.4271/2014-01-0646
Publisher: ASMEDC
Date: 2002
Abstract: Volutes are widely used in industrial process, refrigeration system, small gas turbines and gas pipeline centrifugal compressors as the transition from the impeller-diffuser to the pipings, because of their simple structure, ease of production and wide operating range. This paper illustrates a new design tool that incorporates a new volute design system that integrates and automates geometry generation, grid generation and aerodynamic analysis. In optimizing the available technology in terms of grid generation, CFD, and computer graphics, the program will utilize existing technology used by industry to generate a powerful volute design tool. The design tool is programmed in a way that integrates the features and methods a designer would use for volute design. This is fundamentally by means of geometrical constraints and/or functional relationships. Grids can be generated in minutes accommodating geometrical changes thus reducing the bottlenecks associated with geometry/grid generation for CFD applications. Prior to most CFD analysis work, a structured grid must be produced ensuring high quality such that convergence is assured and the time to convergence of the solution is minimized. However, there are usually only a few people that have the required skills to produce the geometry and generate a high quality structured grid. In essence, the tool provides a sidestep around both the geometry generation and the grid generation process. It automates the process such that anybody can produce a high quality grid from the geometry and move straight to the CFD component of the work and hence can incorporate CFD as part of the design process. The volute design tool will enable the user to generate a family of volutes and display 2D volute cross sections and 3D solid models of the scroll, diffuser inlet, discharge conic, and connecting channel. Separate interfaces will be written to accommodate the different operating systems. The geometry generation will be written in windows however, a separate interface will be written to produce the grid being compatible in NT, Unix, and Linux platforms.
Publisher: Springer International Publishing
Date: 14-08-2019
Publisher: American Society of Mechanical Engineers
Date: 13-06-2016
DOI: 10.1115/GT2016-56430
Abstract: The Dry-Low-NOx (DLN) Micromix combustion technology has been developed as low emission combustion principle for industrial gas turbines fueled with hydrogen or syngas. The combustion process is based on the phenomenon of jet-in-crossflow-mixing. Fuel is injected perpendicular into the air-cross-flow and burned in a multitude of miniaturized, diffusion-like flames. The miniaturization of the flames leads to a significant reduction of NOx emissions due to the very short residence time of reactants in the flame. In the Micromix research approach, CFD analyses are validated towards experimental results. The combination of numerical and experimental methods allows an efficient design and optimization of DLN Micromix combustors concerning combustion stability and low NOx emissions. The paper presents a comparison of several numerical combustion models for hydrogen and hydrogen-rich syngas. They differ in the complexity of the underlying reaction mechanism and the associated computational effort. For pure hydrogen combustion a one-step global reaction is applied using a hybrid Eddy-Break-up model that incorporates finite rate kinetics. The model is evaluated and compared to a detailed hydrogen combustion mechanism derived by Li et al. including 9 species and 19 reversible elementary reactions. Based on this mechanism, reduction of the computational effort is achieved by applying the Flamelet Generated Manifolds (FGM) method while the accuracy of the detailed reaction scheme is maintained. For hydrogen-rich syngas combustion (H2-CO) numerical analyses based on a skeletal H2/CO reaction mechanism derived by Hawkes et al. and a detailed reaction mechanism provided by Ranzi et al. are performed. The comparison between combustion models and the validation of numerical results is based on exhaust gas compositions available from experimental investigation on DLN Micromix combustors. The conducted evaluation confirms that the applied detailed combustion mechanisms are able to predict the general physics of the DLN-Micromix combustion process accurately. The Flamelet Generated Manifolds method proved to be generally suitable to reduce the computational effort while maintaining the accuracy of detailed chemistry. Especially for reaction mechanisms with a high number of species accuracy and computational effort can be balanced using the FGM model.
Publisher: American Society of Mechanical Engineers
Date: 17-06-2019
DOI: 10.1115/GT2019-90095
Abstract: The negative effects on the earth’s climate make the reduction of the potent greenhouse gases carbon-dioxide (CO2) and nitrogen oxides (NOx) an imperative of the combustion research. Hydrogen based gas turbine systems are in the focus of the energy producing industry, due to their potential to eliminate CO2 emissions completely as combustion product, if the fuel is produced from renewable and sustainable energy sources. Due to the difference in the physical properties of hydrogen-rich fuel mixtures compared to common gas turbine fuels, well established combustion systems cannot be directly applied for Dry Low NOx (DLN) hydrogen combustion. The paper presents initial test data of a recently designed low emission Micromix combustor adapted to flexible fuel operation with variable fuel mixtures of hydrogen and methane. Based on previous studies, targeting low emission combustion of pure hydrogen and dual fuel operation with hydrogen and syngas (H2/CO 90/10 vol.%), a FuelFlex Micromix combustor for variable hydrogen methane mixtures has been developed. For facilitating the experimental low pressure testing the combustion chamber test rig is adapted for flexible fuel operation. A computer-controlled gas mixing facility is designed and installed to continuously provide accurate and homogeneous hydrogen methane fuel mixtures to the combustor. An evaluation of all major error sources has been conducted. In the presented experimental studies, the integration-optimized FuelFlex Micromix combustor geometry is tested at atmospheric pressure with hydrogen methane fuel mixtures ranging from 57 vol.% to 100 vol.% hydrogen in the fuel. For evaluating the combustion characteristics, the results of experimental exhaust gas analyses are applied. Despite the design compromise, that takes into account the significantly different fuel and combustion properties of the applied fuels, the initial results confirm promising operating behaviour, combustion efficiency and pollutant emission levels for flexible fuel operation. The investigated combustor module exceeds 99.4% combustion efficiency for hydrogen contents of 80–100% in the fuel mixture and shows NOx emissions less than 4 ppm corrected to 15 vol.% O2 at the design point.
Publisher: SAE International
Date: 04-2014
DOI: 10.4271/2014-01-0642
Publisher: Informa UK Limited
Date: 06-2006
Publisher: SAGE Publications
Date: 26-06-2015
Abstract: Spectrometric oil analysis has been a popular technique used by oil analysis laboratories to determine the concentration of elements in an oil s le. The primary application of this technique has been the identification of fine wear in lubricated systems as an indicator of abnormal wear in order to prevent failure. It has also found some use for monitoring contaminants and fluid additives. While the literature has varying accounts of the effectiveness of this technique for machinery condition monitoring purposes, the introduction of fine filtration to many modern machines has profound implications for the effectiveness of spectrometric oil analysis. This paper will assess the effectiveness of spectrometric oil analysis in a fine filtered system and compare it with the results from an inductive wear debris sensor. The inductive wear debris sensor is a relatively new sensor for detecting abnormal wear in recirculating lubrication systems. A combination of experimental data and aircraft data is presented.
Publisher: Springer International Publishing
Date: 26-05-2015
Publisher: Elsevier BV
Date: 03-2019
Publisher: ASME International
Date: 26-04-2018
DOI: 10.1115/1.4038882
Abstract: The Dry-Low-NOx (DLN) Micromix combustion technology has been developed as low emission combustion principle for industrial gas turbines fueled with hydrogen or syngas. The combustion process is based on the phenomenon of jet-in-crossflow-mixing (JICF). Fuel is injected perpendicular into the air-cross-flow and burned in a multitude of miniaturized, diffusion-like flames. The miniaturization of the flames leads to a significant reduction of NOx emissions due to the very short residence time of reactants in the flame. In the Micromix research approach, computational fluid dynamics (CFD) analyses are validated toward experimental results. The combination of numerical and experimental methods allows an efficient design and optimization of DLN Micromix combustors concerning combustion stability and low NOx emissions. The paper presents a comparison of several numerical combustion models for hydrogen and hydrogen-rich syngas. They differ in the complexity of the underlying reaction mechanism and the associated computational effort. The performance of a hybrid eddy-break-up (EBU) model with a one-step global reaction is compared to a complex chemistry model and a flamelet generated manifolds (FGM) model, both using detailed reaction schemes for hydrogen or syngas combustion. Validation of numerical results is based on exhaust gas compositions available from experimental investigation on DLN Micromix combustors. The conducted evaluation confirms that the applied detailed combustion mechanisms are able to predict the general physics of the DLN-Micromix combustion process accurately. The FGM method proved to be generally suitable to reduce the computational effort while maintaining the accuracy of detailed chemistry.
Publisher: Inderscience Publishers
Date: 2018
Publisher: Elsevier BV
Date: 11-2018
DOI: 10.1016/J.JMBBM.2018.07.031
Abstract: A significant number of hip replacements (HR) fail permanently despite the success of the medical procedure, due to wear and progressive loss of osseointegration of implants. An ideal model should consist of materials with a high resistance to wear and with good biocompatibility. This study aims to develop a new method of grafting the surface of selective laser melted (SLM) titanium alloy (Ti-6Al-4V) with poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC), to improve the surface properties and biocompatibility of the implant. PMPC was grafted onto the SLM fabricated Ti-6Al-4V, applying the following three techniques ultraviolet (UV) irradiation, thermal heating both under normal atmosphere and UV irradiation under N
Publisher: ASMEDC
Date: 2009
Abstract: An experimental and theoretical investigation was undertaken to identify and evaluate the key technical issues surrounding the ‘drop-in’ utilisation of alternative bio-fuels in aviation gas-turbine propulsion systems. Region-suitable biofuels were identified and suitability evaluated based on the following three criteria: ‘drop-in’ capability, environmental and economic sustainability and industrialisation prospects. Bio-fuel engine performance will be evaluated based on the specific fuel consumption, specific thrust, nature and quantity of emissions through theoretical modelling. This paper outlines a variety of different bio-fuel type options that were investigated. By using engineering and scientific methodology the fuels were evaluated to verify their suitability for gas-turbine aviation use. The eventual bio-fuel selected for further evaluation was a locally produced mustard seed oil derivative bio-fuel which was blended at various blend ratios with standard Jet A-1 turbine fuel. Verification testing processes for future investigation are detailed. In addition to engine performance evaluation endeavours, this paper also seeks to address and offer recommendations in the areas of bio-fuel production, transport, storage, certification and emissions.
Publisher: Springer International Publishing
Date: 17-10-2018
Publisher: ASMEDC
Date: 2007
Abstract: Flow separation is a phenomenon that occurs in all kinds of supersonic nozzles sometimes during run-up and shut-down operations. Especially in expansion nozzles of rocket engines with large area ratio, flow separation can trigger strong side loads that can damage the structure of the nozzle. The investigation presented in this paper seeks to establish measures that may be applied to alter the point of flow separation. In order to achieve this, a supersonic nozzle was placed at the exit plane of the conical nozzle. This resulted in the generation of cross flow surrounding the core jet flow from the conical nozzle. Due to the entrainment of the gas stream from the conical nozzle the pressure in its exit plane was found to be lower than that of the ambient. A Cold gas instead of hot combustion gases was used as the working fluid. A mathematical simulation of the concept was validated by experiment. Measurements confirmed the simulation results that due to the introduction of a second nozzle the pressure in the separated region of the conical nozzle was significantly reduced. It was also established that the boundary layer separation inside the conical nozzle was delayed thus allowing an increased degree of overexpansion. The condition established by the pressure measurements was also demonstrated qualitatively using transparent nozzle configurations.
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.JMBBM.2019.103412
Abstract: The incidence of total hip arthroplasty (THA) has been evidently growing over the last few decades. Surface modification, such as polymer grafting onto implant surfaces using poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC), has been gaining attention due to its excellent biocompatibility and high lubricity behaviour resulting in reducing surgical recurrence number and increasing implant lifetime. Investigating thermal stability and mechanical properties of the grafted polymer is, therefore, extremely important as these properties define the failure mechanism of implants. This study focuses on optimising monomer concentration to achieve the best physical, thermal and mechanical properties of the grafted additively manufactured titanium (Ti6Al4V) implants. Three different concentration of monomers, 0.4 M, 0.6 M and 0.8 M, were investigated, and grafted implants were characterised. The results from thermal analysis confirmed that the PMPC polymer is thermally stable for implant applications regardless of the monomer concentrations. A significant reduction in Young's modulus of polymer grafted s les (33.2-42.9%), in comparison with untreated Ti6Al4V s les and consequent improvement of wear resistance and elasticity behaviour, proved the potentiality of polymer films for implant applications. In summary, polymer grafted implant prepared with 0.6 M monomer concentration showed the optimal thermal, physical and wear resistance properties.
Publisher: AIP Publishing
Date: 06-2020
DOI: 10.1063/1.5133981
Abstract: Shape memory alloys (SMAs) are a class of functional materials with the ability to regain their original shapes after a large inelastic deformation upon external stimuli. In recent years, SMAs have been employed in many applications in different fields. Nitinol is the most widely used SMA due to its outstanding properties such as shape memory effect, superelasticity, biocompatibility, and corrosion resistance among other types of SMAs. Some efforts are also made to implement SMAs on filtration devices that require deployable structures. This motivates the authors to write a review of the recent developments in the field of SMA based filtration devices as far as the use of SMAs is concerned. The present work provides a brief overview of history and basics of SMAs. This paper then reviews and discusses the recent progress and applications of SMA based filtration devices and the challenges of these filtration devices. It is found that most devices are made of nitinol. The aim of this paper is to introduce SMA based filtration devices and promote future developments of functional filtration applications.
Publisher: ASMEDC
Date: 2005
Abstract: The main function of the crosshead bearing of a crosshead engine is to transmit the load from the connecting rod, which is directly attached to the piston of the engine, through a second rod to the guide shoe, which bears the entire crosshead. Apart from this function it enables the large normal forces, which are usually borne by the piston skirt in the case of a trunk piston engine, to be transmitted to the guide shoe from which it is subsequently transmitted to the rails along which the guide shoe glides. The dynamics of the crosshead bearing is such that the bearing pin is subjected to very low levels of incomplete rotation resembling that executed by a pendulum over a reduced arc. The bearing is also subjected to the load in only one direction. These operating conditions augur poorly for the formation of the hydrodynamic oil film necessary to support the imposed load. This type of bearing is therefore susceptible to considerable friction losses and significant wear as a result of lack of the capacity to generate lubrication film. This paper evaluates a model to determine the levels of achievable hydrodynamic film and the measures introduced to generate a hydrostatic squeeze lubricating film in the bearing as a result of the introduction of high pressure oil during part of the operating cycle of the engine.
Publisher: ASMEDC
Date: 2005
Abstract: In the computation of aeroacoustic noise, both the Lighthill analogy and the linearized Euler approaches require the definition of source terms involving instantaneous flow fluctuations, which are generally obtained from either Direct Numerical Simulation (DNS) or Large Eddy Simulation (LES). However, these approaches are not economically viable in terms of computational resources, as they require very fine grids to deliver accurate results. Therefore, the Stochastic Velocity Field generation model (SVFG) has has been applied in this paper. The SVFG model is based on the concept of the Stochastic Noise Generation and Radiation (SNGR) without sound propagation and linearized equations. The SVFG model uses time-averaged quantities from the Reynolds Averaged Navier-Stokes equations (RANS) to generate a synthetic time dependent turbulent flow field. The turbulent fluctuations are modeled using a stochastic description of the three-dimensional turbulent motion with a discrete set of Fourier modes. This synthetic turbulent field represents many of the characteristics of real turbulence. Nevertheless, it still has some imperfections although it exhibits the expected correlation length and the required ratio of length scales, it does not predict the convective properties of shear flow turbulence, as the approach generates homogenous and isotropic turbulence. These properties are shown in this paper with the test case of an axial-symmetrical subsonic jet. The SVFG model is used to generate the turbulent flow field, which then is used to compare with actual experiment measurement and other prediction methods. The results of the comparison show strengths and weaknesses of the model. Since the SVFG approach is relatively low cost when compared to both LES and DNS, it offers an attractive alternative to derive the turbulent flow field.
Publisher: SAGE Publications
Date: 02-08-2013
Abstract: Rolling contact fatigue (RCF) is a common failure mode for rolling element bearings, however evidence of precursor failure modes or initiators can be lost or obscured by the subsequent severe damage caused by RCF. Although electric discharge damage (EDD) is not normally associated with rolling element bearings in aviation propulsion applications, it can occur and may not be instantly recognisable. Unlike factors such as lubricant cleanliness or misalignment, EDD does not normally form part of the life prediction of aviation propulsion rolling element bearings. Early identification of EDD and subsequent mitigation or elimination is, therefore, essential to prevent significant reduction in life or failure of rolling element bearings. This paper will review the phenomenon of EDD and discuss several recent ex les observed in aviation propulsion systems.
Publisher: SAE International
Date: 08-04-2013
DOI: 10.4271/2013-01-0879
Publisher: SAGE Publications
Date: 19-04-2020
Abstract: Splash-lubricated gearboxes are widely used in many industries. Contaminant removal systems are rarely employed in splash-lubricated gearboxes, such as some gearboxes are used in helicopters and mining machines. The maintenance of lubrication systems in those machines relies on periodic onsite inspection and lubricant change. However, wear debris generated during operation will suspend in lubricant and cause damage to contacting surfaces of gearbox’s components. In this first part of a two-part paper, a novel light-weight passive filtration system that utilises gravitational sedimentation and shape memory alloys is presented for unfiltered splash-lubricated gearboxes. A predictive model is developed for the estimation of flake-like wear particles’ settling behavior in the lubricant. Experiments based on a simplified test rig are also conducted to validate the theoretical results. This mathematical model can also be used to elucidate the impact of sedimentation time of wear particles on the cleanliness of the lubricant after the installation of passive filtration system.
Publisher: Springer International Publishing
Date: 28-06-2018
Publisher: Informa UK Limited
Date: 31-07-2017
DOI: 10.1080/15389588.2017.1316843
Abstract: Thoracic side airbags (tSABs) deploy within close proximity to the occupant. Their primary purpose is to provide a protective cushion between the occupant and the intruding door. To date, various field studies investigating their injury mitigation has been limited and contradicting. The research develops efficacy estimations associated for seat-mounted tSABs in their ability to mitigate injury risk from the German collision environment. A matched cohort study using German In-Depth Accident Study (GIDAS) data was implemented and aims to investigate the efficacy of seat-mounted tSAB units in preventing thoracic injury. Inclusion in the study required a nearside occupant involved in a lateral collision where the target vehicle exhibited a design year succeeding 1990. Collisions whereby a tSAB deployed were matched on a 1:n basis to collisions of similar severity where no airbag was available in the target vehicle. The outcome of interest was an incurred bodily or thoracic regional injury. Through conditional logistic regression, an estimated efficacy value for the deployed tSAB was determined. A total of 255 collisions with the deployed tSAB matched with 414 collisions where no tSAB was present. For the given s le, results indicated that the deployed tSAB was not able to provide an unequivocal benefit to the occupant thoracic region, because in iduals exposed to the deployed tSAB were at equal risk of injury (Thorax Maximum Abbreviated Injury Scale (Tho.MAIS)2+ odds ratio [OR] = 1.04, 95% confidence interval [CI], 0.41-2.62 Tho.MAIS3+ OR = 1.15, 95% CI, 0.41-3.18). When attempting to isolate an effect for skeletal injuries, a similar result was obtained. Yet, when the tSAB was coupled with a head curtain airbag, a protective effect became apparent, most noticeable for head/face/neck (HFN) injuries (OR = 0.59, 95% CI, 0.21-1.65). The reduction in occupant HFN injury risk associated with the coupled tSAB and curtain airbag may be attributable to its ability to provide coverage over previous mechanisms of injury. Yet, the sole presence of the tSAB showed no ability to provide additional benefit for the occupant's thoracic region. Future work should identify mechanisms of injury in tSAB cases and attempt to quantify improvements in the vehicle's ability to resist intrusion.
Publisher: SAE International
Date: 24-10-2016
DOI: 10.4271/2016-01-9076
Publisher: Informa UK Limited
Date: 11-04-2018
DOI: 10.1080/15389588.2018.1428314
Abstract: Thoracic side airbags (tSABs) were integrated into the vehicle fleet to attenuate and distribute forces on the occupant's chest and abdomen, dissipate the impact energy, and move the occupant away from the intruding structure, all of which reduce the risk of injury. This research piece investigates and evaluates the safety performance of the airbag unit by cross-correlating data from a controlled collision environment with field data. We focus exclusively on vehicle-vehicle lateral impacts from the NHTSA's Vehicle Crash Test Database and NASS-CDS database, which are replicated in the controlled environment by the (crabbed) barrier impact. Similar collisions with and without seat-embedded tSABs are matched to each other and the injury risks are compared. Results indicated that dummy-based thoracic injury metrics were significantly lower with tSAB exposure (P <.001). Yet, when the controlled collision environment data were cross-correlated with NASS-CDS collisions, deployment of the tSAB indicated no association with thoracic injury (tho. MAIS 2+ unadjusted relative risk [RR] = 1.14 90% confidence interval [CI], 0.80-1.62 tho. MAIS 3+ unadjusted RR = 1.12 90% CI, 0.76-1.65). The data from the controlled collision environment indicated an unequivocal benefit provided by the thoracic side airbag for the crash dummy however, the real-world collisions demonstrate that no benefit is provided to the occupant. This has resulted from a noncorrelation between the crash test/dummy-based design taking the abstracting process too far to represent the real-world collision scenario.
Publisher: American Society of Mechanical Engineers
Date: 08-07-2012
Abstract: For the plain orifice nozzle configuration, breakup mode analysis of the issuing liquid jet has been extensively, over the years, undertaken. The works of Rayleigh, Haenlein, Ohnesorge, Reitz and others have used an Ohnesorge-Reynolds chart to clearly characterize breakup into four distinct modes. These include: (1) Rayleigh, (2) first wind induced, (3) second wind induced, and (4) prompt atomization. Planar liquid sheet flows have not undergone such intensive characterization analysis. In this work a non-expanding (nor thinning) liquid sheet is injected into a quiescent volume of gas from a planar nozzle of constant opening height. The flow has no co-flowing gas stream nor air-assistance to drive the disintegration. The nozzle configuration and subsequent liquid primary breakup is somewhat similar to an outward opening fuel injector having an annular outlet with a large radius to needle lift height ratio. The numerical experiments in this work use a high fidelity Computational Fluid Dynamics (CFD) modeling approach. This includes the Volume-Of-Fluid (VOF) two-phase method to represent the liquid and gas fluids both considered to be incompressible, coupled with the Large Eddy Simulation (LES) treatment of turbulence modeling. The initial primary breakup of the liquid sheet into large droplets, ligaments and other structures is the main focus of the modeling. As such, secondary breakup and possible evaporation of the liquid is not considered. Due to the configuration of the planar nozzle, upstream cavitation of the liquid within the nozzle is also not considered. Breakup studies were conducted within the Reynolds number range of 3,000 to 23,400, and Ohnesorge number range of 0.004 to 0.1. Results are extensively validated with the works of Heukelbach and Scholz. In-nozzle velocity profiles are characterized with Reynolds number showing laminar, semi- and fully-turbulent states in the flow boundary layer and core. Velocity profile relaxation is studied as the liquid sheet transitions from a wall-bounded flow within the nozzle to a free shear flow surrounded by gas. Particularly, the axial velocity component is seen to weaken, whilst the sheet normal velocity component strengthens and aids in disintegration of the liquid sheet.
Publisher: Informa UK Limited
Date: 2000
Publisher: Springer International Publishing
Date: 28-06-2018
Publisher: Informa UK Limited
Date: 2000
Publisher: Informa UK Limited
Date: 2000
Publisher: SAGE Publications
Date: 24-11-2014
Abstract: A relatively recent development for the condition monitoring of oil-wetted machinery has been the in-line full-flow inductive wear debris sensor (hereafter referred to as inductive wear debris sensors). These sensors detect a disturbance to a magnetic field caused by metallic wear debris shed from deteriorating dynamic components that is entrained in the lubricant. Applications for these sensors currently include (but are not limited to) aviation machinery, wind-turbine generators, marine propulsion systems, and locomotives. Inductive wear debris sensors can distinguish between ferromagnetic and nonferromagnetic particles as well as providing size and other related information. One of the primary advantages of this sensor type is that the detectable size range is broad and may be used to track the progress of an incipient failure such as the rolling contact fatigue of a bearing or gear as it occurs. One aspect that has received little attention in the literature is the methodology for determining a suitable limit for a particular application. Limits are a critically important aspect of machinery condition monitoring and need to be established by a robust and reliable method otherwise unnecessary maintenance can occur or an incipient fault may be missed. This paper describes a generic method for determining a physically meaningful debris limit for a deteriorating rolling element bearing when utilizing an inductive wear debris sensor.
Publisher: Elsevier BV
Date: 11-2018
Publisher: Springer Singapore
Date: 2019
Publisher: Elsevier BV
Date: 11-2001
Location: Germany
No related grants have been discovered for Sylvester Abanteriba.