Life Cycle Management of Infrastructures

By definition, life cycle management (LCM) is a framework “of concepts, techniques, and procedures to address environmental, economic, technological, and social aspects of products and organizations in order to achieve continuous ‘sustainable’ improvement from a life cycle perspective” (Hunkeler et al.\ua02001). Thus, LCM theoretically integrates all sustainability dimensions, and strives to provide a holistic perspective. It also assists in the efficient and effective use of constrained natural and financial resources to reduce negative impacts on society (Sonnemann and Leeuw\ua02006; Adibi et al.\ua02015). The LCM of infrastructures is the adaptation of product life cycle management (PLM) as techniques to the design, construction, and management of infrastructures. Infrastructure life cycle management requires accurate and extensive information that might be generated through different kinds of intelligent and connected information workflows, such as building information modeling (BIM)

Utilisation of bio-fuels in aviation gas turbines: An experimental and theoretical evaluation

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

Status of surface modification techniques for artificial hip implants

Surface modification techniques have been developed significantly in the last couple of decades for enhanced tribological performance of artificial hip implants. Surface modification techniques improve biological, chemical and mechanical properties of implant surfaces. Some of the most effective techniques, namely surface texturing, surface coating, and surface grafting, are applied to reduce the friction and wear of artificial implants. This article reviews the status of the developments of surface modification techniques and their effects on commonly used artificial joint implants. This study focused only on artificial hip joint prostheses research of the last 10 years. A total of 27 articles were critically reviewed and categorized according to surface modification technique. The literature reveals that modified surfaces exhibit reduced friction and enhanced wear resistance of the contact surfaces. However, the wear rates are still noticeable in case of surface texturing and surface coating. The associated vortex flow aids to release entrapped wear debris and thus increase the wear particles generation in case of textured surfaces. The earlier delamination of coating materials due to poor adhesion and graphitization transformation has limited the use of coating techniques. Moreover, the produced wear debris has adverse effects on biological fluid. Conversely, the surface grafting technique provides phospholipid like layer that exhibited lower friction and almost zero wear rates even after a longer period of friction and wear test. The findings suggest that further investigations are required to identify the role of surface grafting on film formation and heat resistance ability under physiological hip joint conditions for improved performance and longevity of hip implants

Characterization of liquid sheet breakup using numerical experiments

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

Electric discharge damage in aircraft propulsion bearings

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 examples observed in aviation propulsion systems

Manufacture, qualification and approval of new aviation turbine fuels and additives

Energy consumption has always been instrumental in raising the living standards of the people of this planet. Unfortunately, it is predicted that the fossils fuels which have heretofore been the main source of energy will be practically depleted in 50 years. It is also now abundantly clear that the use of the fossil fuels involves environmentally damaging emissions such as CO2 , SO2 and a variety of Nitrogen Oxides. The lifting of hundreds of millions of people in the developing world from poverty into the middle class has greatly increased the demand for energy, which is currently derived mainly from fossil fuels and thus dramatically exacerbating the pollution trends. Due to the limiting nature of the fossil fuels and their undesirable pollution effects, there is a concerted effort to find alternative and less polluting energy sources. Since the aviation industry is on the cusp of unprecedented expansion to accommodate the travelling needs of the rapidly increasing middle class of the emerging economies, the quest for alternative fuels, such as biofuels, for aviation has assumed a form of urgency. Since the approval of the use of Fischer Tropsch Hydroprocessed Synthesized Paraffinic Kerosenes (SPK) produced by Sasol as a blending stock in DEFSTAN 91-91 research has been ongoing to introduce feedstock from alternative feedstock using different methods. However, the use of biofuels in aviation presents greater restrictions for any candidate fuel and may require extensive changes to engines. The aim of this paper is to review and provide a guideline in the production and certification of aviation

Investigation of flow seperation inside a conical rocket nozzle with the aid of an annular cross flow

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

An advanced zero-head hydro-propulsion

This paper provides an overview on the theoretical aspects of a newly developed concept for harnessing the kinetic energy contained in random fluid flows of particles. Because of a number of constraints associated with current power-generating methods of utilisation of random and turbulent zero-head flows, such practices are bound to be inefficient and expensive. However, using a recently developed system and on the basis of the features introduced by the new concept, a large portion of the kinetic energy available from such zero-levelled, multidirectional and turbulent fluid motions can be captured effectively

An overview on dry low NOx micromix combustor development for hydrogen-rich gas turbine applications

The paper presents a survey of the interactive optimization cycle at Aachen University of Applied Sciences, used for the development of a new low emission Micromix combustor module for application in hydrogen fueled industrial gas turbines. During the development process, experimental and numerical methods are applied to optimize a given baseline combustor with 0.3 mm nozzles with respect to combustion efficiency, combustion stability, higher thermal power output per nozzle and reduced manufacturing complexity. Within the described research cycle combustion and flow simulations are used in the context of parametric studies for generating optimized burner geometries and the phenomenological interpretation of the experimental results. Experimental tests, carried out on an atmospheric combustion chamber test stand provide the basis for validation of simulation results and proof of the predicted combustion characteristics under scaled down gas turbine conditions. In the presented studies, an integration-optimized Micromix combustor with a nozzle diameter of 0.84 mm is tested at atmospheric pressure over a range of gas turbine operating conditions with hydrogen fuel. The combustor module offers an increase in the thermal power output per nozzle by approx. 390% at a significant reduced number of injectors when compared to the baseline design. This greatly benefits manufacturing complexity and the robustness of the combustion process against fuel contamination by particles. During atmospheric testing, the optimized combustor module shows satisfactory operating behavior, combustion efficiency and pollutant emission level. Within the evaluated operating range, which correlates to gas turbine part-, full- and overload conditions, the investigated combustor module exceeds 99% combustion efficiency. The Micromix combustor achieves NO x emissions less than 2.5 ppm corrected to 15 Vol% O 2 at the design point. Based on numerical analyses and experimental low pressure testing, a