Oil cooling system for a gas turbine engine

A gas turbine engine fuel delivery and control system is provided with means to recirculate all fuel in excess fuel control requirements back to the aircraft fuel tank. This increases the fuel pump heat sink and decreases the pump temperature rise without the addition of valving other than normally employed. A fuel/oil heat exchanger and associated circuitry is provided to maintain the hot engine oil in heat exchange relationship with the cool engine fuel. Where anti-icing of the fuel filter is required, means are provided to maintain the fuel temperature entering the filter at or above a minimum level to prevent freezing thereof. In one embodiment, a divider valve is provided to take all excess fuel from either upstream or downstream of the fuel filter and route it back to the tanks, the ratio of upstream to downstream extraction being a function of fuel pump discharge pressure

Fuel leak detection on large transport airplanes

Fuel leakage has the risk of being ignited by external ignition sources, and therefore it is important to detect any fuel leakage before the departure of the aircraft. Currently, there are no fuel leak detection systems installed on commercial aircrafts, to detect fuel tank leakage, while only a small number of more recent aircraft, have a fuel monitoring system, that generates a fuel leak-warning message in cockpit in the case of fuel imbalance between the tanks. The approach proposed in this paper requires the fuel vent ports on the wings to be replaced with fuel vent valves, which can be controlled to be in open or close position. The fuel vent valve will be in close position, when certain conditions are fulfilled (all the related fuel valves closed, pumps not operating, etc.), the fuel tank ullage area is then pressurized to 4 psi and the rate of change of the pressure is measured over a period. Several experiments have been conducted and, the result show that a continuous fuel leak of one liter per minute can be detected. Further experiments show that if the fuel tank is pressurized to higher pressures, a fuel leak can be detected sooner

Components of Alaska Fuel Costs: An Analysis of the Market Factors and Characteristics that Influence Rural Fuel Prices

Many Alaskans face extremely high, volatile fuel prices. Little is publicly known about the actual structure of Alaska’s rural fuel markets and what drives prices at the community level. The Alaska State Senate Finance Committee asked economists at the University of Alaska Anchorage, Institute of Social and Economic Research (ISER) to investigate rural Alaska fuel markets and identify policy options that could be considered for legislative action to reduce fuel prices. This study is both an update and an evolution of previous ISER Components of Fuel Costs studies.1 It does not include road-accessible communities.Alaska State Legislature Senate Finance CommitteeAcknowledgements / Executive Summary / Introduction / Western Alaska Fuel Market / Ice Free Coastal Alaska Fuel Market / Community Fuel Survey Results / Policy Options / References / Glossary of Terms / Appendix A. Results of Community Fuel Price Survey January 201

Neutronics Studies on the NIST Reactor Using the GA LEU fuel

The National Bureau of Standards Reactor (NBSR) located on the National Institute of Standards and Technology (NIST) Gaithersburg campus, is currently underway of fuel conversion from high enriched uranium (HEU) fuel to low enriched uranium (LEU) fuel. One particular challenging part of the conversion of the NBSR is the high average flux level (2.5×1014 n/cm2-s) required to maintain experimental testing capabilities of the reactor, without significant changes to the external structures of the reactor. Recently the General Atomics (GA) Training Research Isotopes General Atomics (TRIGA) fuel has shown some promising features as a LEU candidate for the high performance research reactors such as the NBSR. The GA fuel has a long history of success in conversion of research reactors since it was developed in 1980s. The UZrH compound in the GA fuel has seen success in long term TRIGA reactors, and is a proven safe LEU alternative. This study performs a neutronics evaluation of the TRIGA fuel under the schema of the NBSR’s heavy conversion requirements in order to examine whether the TRIGA fuel is a viable option for conversion of the NBSR. To determine the most optimal path of conversion, we performed a feasibility study with particular regard to the fuel dimensions, fuel rod configurations, cladding, as well as fuel structure selection. Based on the outcome of the feasibility study, an equilibrium core is then generated following the NBSR’s current fuel management schema. Key neutronics performance characteristics including flux distribution, power distribution, control rod (i.e., shim arms) worth, as well as kinetics parameters of the equilibrium core are calculated and evaluated. MCNP6, a Monte Carlo based computational modeling software was intensively used to aid in these calculations. The results of this study will provide important insight on the effectiveness of conversion, as well as determine the viability of the conversion from HEU to LEU using the GA fuel

Fuel system technology overview

Fuel system research and technology studies are being conducted to investigate the correlations and interactions of aircraft fuel system design and environment with applicable characteristics of the fuel. Topics include: (1) analysis of in-flight fuel temperatures; (2) fuel systems for high freezing point fuels; (3) experimental study of low temperature pumpability; (4) full scale fuel tank simulation; and (5) rapid freezing point measurement

Наближена оцінка температурного стану керамічного ядерного палива в циліндричних твелах та впливу на нього процесів і параметрів конструкцій активної зони реактора

The approximate mathematical model of the temperature state of ceramic nuclear fuels in cylindrical fuel elements was proposed in the form of linear ordinary differential equation and the boundary conditions. The theory of heat conduction and assumptions about the axial symmetry and absence of heat flows along axis of fuel element, which allow to simplify the common equations in cylindrical coordinates, are the basis of the proposed simplified mathematical model for approximate estimating the temperature state of the nuclear fuel. The intensity of volume heat sources in fuel element was taken into account by using the average values corresponding with the heat power and the structural characteristics of a nuclear reactor core. The conception about the heat transfer coefficient was used for modeling interaction between the fuel and the heat carrier. This heat transfer coefficient depends on characteristic sizes and heat conductions of constituted materials of the fuel element and allows to estimate influence of these on the temperature state of the nuclear fuel. The analytical solution for the temperature of a ceramic fuel in cylindrical fuel elements was obtained and was used for researching. It was shown that the heat conductivity of the fuel has significantly influences both the average temperature and the difference between the inner and outer temperatures in the fuel pellet. At the same time, other parameters have significant influence only on the average temperature of the fuel pellet. Due to these, it is necessary to consider the temperature dependence of the thermal conductivities of the materials constituted the fuel elements for more precisely estimations the temperature state of the fuel pellets, which will lead to nonlinear equations will required the numerical methods for their solving.На основі математичної моделі теплопровідності з урахуванням ряду гіпотез спрощення отримані наближені кількісні оцінки температурного стану керамічного ядерного палива в активній зоні ядерного енергетичного реактора. Досліджено вплив на температурний стан ядерного палива температури теплоносія, тепловіддачі від оболонки твела до теплоносія, теплопровідності оболонки, газового наповнювача твела, керамічного палива, а також розмірів палива. Показано, що теплопровідності палива і конструкційних матеріалів твела мають найбільший вплив на температурний стан керамічного ядерного палива

Fuel distribution measurements in a model low NOx double annular combustor using laser induced fluorescence

Planar laser induced fluorescence (PLIF) was employed in a three sector, low NOx double annular combustor in order to characterise the combusting fuel spray. Naphthalene was employed as a fluorescent agent in odourless kerosene in order to determine the behavior of the light fractions in the fuel vapour, and the light to medium fractions in the fuel spray, while 2,5 di-phenyl oxizol (ppo) was employed to determine the behavior of the heavy fractions in the fuel spray. Counter-swirl air blast atomizing fuel injectors employing a nominal fuel spray included cone angle of 90 deg were employed to inject the kerosene fuel into the double annular combustor. Radial and axial measurements were performed on the combusting spray. Spatial variations in fuel spray placement were observed, together with radial anisotropy

Texas solution or nuclear nightmare? : as a company in the Lone Star State moves to profit from America's dilemma with spent nuclear fuel, others fear the worst

textThe United States government has sought a permanent disposal site for spent nuclear fuel since 1982. To date, no location for disposing of spent fuel exists. The situation is problematic, because spent nuclear fuel is a high-level radioactive waste. It is a byproduct of nuclear power plants' electricity production. It is also incredibly dangerous material. With the government set to continue relying on the nuclear industry for electricity, the amount of spent nuclear fuel in the United States will continue to grow. Waste Control Specialists, a company headquartered in Dallas, Texas that specializes in low-level nuclear waste disposal, is in the process of applying for a Nuclear Regulatory Commission license to temporarily store spent fuel in Andrews, Texas. If successful, WCS could earn millions of dollars. Company officials are promoting the plan as a solution for America, but opinions from industry experts and residents near Andrews conflict over the safety of transporting and storing spent fuel in Texas.Journalis