Henri Temianka (Concert Programs)

This collection contains material pertaining to the life, career, and activities of Henri Temianka, violin virtuoso, conductor, music teacher, and author. Materials include correspondence, concert programs and flyers, music scores, photographs, and books.https://digitalcommons.chapman.edu/temianka_ephemera/1093/thumbnail.jp

Gas Turbines for Marine Applications

Gas turbines have been established as the main power plant for all medium to large aircraft propulsions due to their superior power-to-weight ratio. They also have a significant and growing share in the power-generation sector as a result of the relatively low initial cost, short installation time, high efficiency when operated in combined cycle configurations, and low emissions compared to other fossil fuel power plants. However, their share in the marine propulsion sector is very small because of the more economically viable well-established diesel engine systems. Gas turbines have lower efficiency and poor part load performance. They are however favored when space and weight are at a premium or when high speed is required. It is conceivable that their use may increase, as emission restrictions get tougher. This article aims at giving an overview of gas turbine technology aimed at ship propulsion. Future prospects of carbon neutral zero emissions gas turbine systems are also explored

Reinforcement learning for condition-based control of gas turbine engines

A condition-based control framework is proposed for gas turbine engines using reinforcement learning and adaptive dynamic programming (RL-ADP). The system behaviour, specifically the fuel efficiency function and constraints, exhibit unknown degradation patterns which vary from engine to engine. Due to these variations, accurate system models to describe the true system states over the life of the engines are difficult to obtain. Consequently, model-based control techniques are unable to fully compensate for the effects of the variations on the system performance. The proposed RL-ADP control framework is based on Q-learning and uses measurements of desired performance quantities as reward signals to learn and adapt the system efficiency maps. This is achieved without knowledge of the system variation or degradation dynamics, thus providing a through life adaptation strategy that delivers improved system performance. In order to overcome the long standing difficulties associated with the application of adaptive techniques in a safety critical setting, a dual-control loop structure is proposed in the implementation of the RL-ADP scheme. The overall control framework maintains guarantees on the main thrust control loop whilst extracting improved performance as the engine degrades by tuning sets of variable geometry components in the RL-ADP control loop. Simulation results on representative engine data sets demonstrate the effectiveness of this approach as compared to an industry standard gain scheduling

Autoignition Characteristics of Gaseous Fuels at Representative Gas Turbine Conditions,”

ABSTRACT The autoignition properties of gas turbine fuels have been studied for many years and by numerous researchers. The advent of ultra low emission industrial gas turbines using lean premixed technologies has given rise to premixer designs with longer residence times. This, in conjunction with the everincreasing pressure ratios of aeroderivative machines, leads to the potential for autoignition within premix ducts, and has therefore renewed the interest in this field. Although much has been published, data in the region of interest to high pressure ratio gas turbines is extremely sparse. Similarly, modelled autoignition delay times are not very accurate, as most reaction mechanisms were not generated to cover this range of conditions. Hence the uncertainties of autoignition delay times at gas turbine conditions are significant, thereby either imposing over-stringent design limitations or introducing risks of ignition occurrence in the early design process. A series of experiments have been carried out for methane and simulated natural gas fuels in the region of interest, using shock tubes as the test vehicle. The experimental technique was chosen to isolate only the chemical kinetic component of the autoignition delay time, without any additional delays due to mixing and heating of the test gases. Predictive correlations and a chemical kinetic model (the GRI mechanism) have also been used to predict autoignition delay times at the same conditions. The correlation between experiment and prediction has been shown to be poor at representative temperatures. This paper discusses some of the possible explanations for this poor agreement. INTRODUCTION As world-wide emissions legislation is becoming ever more stringent, there is a requirement for combustion engineers to design gas turbine combustors with the capability to produce extremely low levels of NOx and CO in the exhaust. Such low levels of pollutant emissions can only be achieved by extending our understanding of current premixers, to maximise the mixing quality of fuel and air prior to entry into the combustion process. However, with the elevated inlet temperatures and pressures characteristic of high pressure ratio aero-derivative machines, a limit is reached where the time required to fully premix the fuel and air streams becomes comparable with the autoignition delay time for the combustible mixture. A compromise is therefore sought between optimum mixing quality and freedom from autoignition. During the design process, this compromise is currently achieved by experiment. This approach is costly and time-consuming, as it involves the manufacture and testing of many design iterations. If validated predictive chemical kinetic schemes were available, and incorporated into computational fluid dynamics (CFD) codes, then the combustion engineer could have access to a predictive tool, for the optimisation of future designs at minimum cost and in shorter timescales

Calculating and communicating ensemble-based volcanic ash dosage and concentration risk for aviation

During volcanic eruptions, aviation stakeholders require an assessment of the volcanic ash hazard. Operators and regulators are required to make fast decisions based on deterministic forecasts, which are subject to various sources of uncertainty. For a robust decision to be made, a measure of the uncertainty of the hazard should be considered but this can lead to added complexity preventing fast decision making. Here a proof-of-concept risk matrix approach is presented that combines uncertainty estimation and volcanic ash hazard forecasting into a simple warning system for aviation. To demonstrate the methodology, an ensemble of 600 dispersion model simulations is used to characterise uncertainty (due to eruption source parameters, meteorology and internal model parameters) in ash dosages and concentrations for a hypothetical Icelandic eruption. To simulate aircraft encounters with volcanic ash, trans-Atlantic air routes between New York (JFK) and London (LHR) are generated using time-optimal routing software. This approach has been developed in collaboration with operators, regulators and engine manufacturers; it demonstrates how an assessment of ash dosage and concentration risk can be used to make fast and robust flight-planning decisions even 23 when the model uncertainty spans several orders of magnitude. The results highlight the benefit of using an ensemble over a deterministic forecast and a new method for visualising dosage risk along flight paths. The risk matrix approach is applicable to other aviation hazards such as SO2 dosages, desert dust, aircraft icing and clear-air turbulence and is expected to aid flight-planning decisions by improving the communication of ensemble-based forecasts to aviation

KNOWLEDGE MANAGEMENT THROUGH BIM IN CONSTRUCTION SUPPLY CHAINS

ABSTRACT Collaborative working is the key driver for delivering projects in construction industry. In construction supply chains where there is huge knowledge and information flow between the contractors, subcontractors, suppliers and distributors, it is essential to create a collaborative environment during the projects from the bidding phase to the delivery to client. There are some key virtual collaborative tools which have been started to be utilized in major civil engineering projects. The recent concept Building Information modeling (BIM) has been utilized in some major and prestigious construction projects where architects, structural engineers, suppliers, contractors and sub-contractors can work within a three dimensional platform to achieve certain tasks as design, planning, resource allocation, logistics planning, clash detection, coordination and production of design drawings. This paper first explains the recent trends in construction supply chain management, knowledge management and Building Information Modeling. Then, it discusses the integration of Building Information Modeling into construction supply chains for improving information and knowledge management practices throughout the lifecycle of the project which is called as Building Knowledge Model (BKM)

The role of a thermally sprayed CuNiIn underlayer in the durability of a dry-film lubricant system in fretting: a phenomenological model

Dry film lubricant coatings (DFL) are employed to reduce friction and damage in highly loaded contacts. Metallic underlayers, e.g. CuNiIn, can be beneficial however, there is no detailed explanation of the mechanism. This work investigates the effect of CuNiIn on fretting of a MoS2-based DFL in a cylinder-on-flat contact with a fretting amplitude of 300 µm. Two test types were run: 1. DFL without CuNiIn; 2. DFL on the cylindrical sample and DFL with CuNiIn underlayer on the flat sample. The CuNiIn increased the system’s durability. A phenomenological model highlighting the important low friction and highly wear resistant interfacial material is developed. The increased durability is ascribed to the high roughness of the CuNiIn onto which the DFL was deposited

Numerical Simulations of the Cavitating Flow on a Marine Propeller

ABSTRACT This paper deals with numerical simulations of the cavitating flow around a marine propeller operating in open water but mounted on an inclined shaft. The investigation is mainly based on both Large Eddy simulation (LES) and Unsteady Reynolds-Averaged Navier-Stokes (URANS) in combination with a Volume-of-Fluid implementation to capture the liquid-vapour interface and a transport equation-based method for the mass transfer between the phases. Potential flow solver result will also be included to offer a complete picture of the general behaviour and capabilities of a range of computational methods with different levels of detail. Highspeed video recordings from experiments are available for detailed inspection. INTRODUCTION Propeller cavitation is of major concern for vessels in terms of performance degradation, erosion and passenger comfort due to cavitation induced vibrations and noise. However, with increasing demand for faster vessels, and at the same time, for higher propulsive efficiency, it is favourable to decrease the margin of cavitation-free operation or to allow for some "controlled" amounts of sheet cavitation on the propeller blades. These two contradictory demands cause the propeller design to be a game of balancing the pros and cons, and it becomes crucial to be able to determine the characteristics of cavitation and not only its appearance or extent. A common way to study propeller cavitation is through model scale experiments. However, this method has several drawbacks, such as high cost, long execution time, scaling effects, and perhaps more importantly, the limited measurable data that can only indicate the possible existence of a certain problem and will give more limited guidance regarding how to redesign. All these constraints have cultivated the need for developing a reliable, versatile and robust computational tool, to better understand the phenomenon itself as well as to contribute in advanced prediction and design work. Today the standard design tools typically include potential flow solvers on the basis of lifting-line/lifting surface theory, able to predict a reasonable pressure distribution on the blade, but with clear theoretical limitations regarding cavitatio

Improving the operating efficiency of the more electric aircraft concept through optimised flight procedures

The increasing awareness of the environmental risks and costs due to the growing demand in aviation has prompted both academic and industrial research into short-term and long-term technologies which could help address the challenges. Among these, the more electric aircraft has been identified as a key design concept which would make aircraft more environmentally friendly and cost effective in the long run. Moreover, the notion of free-flight and optimised trajectories has been identified as a key operational concept which would help curb the environmental effects of aircraft as well as reduce overall costs. The research in this paper presents a methodology in which these two concepts can be coupled to study the benefits of more electric aircraft (MEA) flying optimised trajectories. A wide range of issues from aircraft performance, engine performance, airframe systems operation, power off-take penalties, emission modelling, optimisation algorithms and optimisation frameworks has been addressed throughout the study. The case study is based on a popular short haul flight between London Heathrow and Amsterdam Schiphol. The culmination of the study establishes the advantage of the MEA over conventional aircraft and also addresses the enhanced approach to the classical aircraft trajectory optimisation problem. The study shows that the operation procedures to achieve a minimum fuel burn are significantly different for a conventional aircraft and MEA. Trajectory optimisation reduced the fuel burn by 17.4% for the conventional aircraft and 12.2% for the more electric compared to the respective baseline cases. Within the constraints of the study, the minimum fuel burn trajectory for the MEA consumed 9.9% less fuel than the minimum fuel burn trajectory for the conventional aircraft