Fuel Control Unit Research Articles

Micro Gas Turbine Operation with Biomass Producer Gas and Mixtures of Biomass Producer Gas and Natural Gas

We report the performance of a commercial recuperated micro gas turbine on biomass producer gas and mixtures of biomass producer gas with natural gas. The biomass producer gas, obtained by gasification at 850 °C with air at atmospheric pressure, contains about 7% H2, 17% CO, 15% CO2, 4% CH4, 2% other hydrocarbons, 2% H2O, and a balance of N2 and Ar from air. It has a net heating value of about 6 MJ/(N m3). The micro gas turbine delivers full power (30 kWe) on gas mixtures with a net heating value of at least 15 MJ/(N m3). For gas of lower heating value, the maximum fuel gas flow allowed by the fuel control unit limits the attainable power. At reduced power, the lower limit for stable operation is a net heating value of about 8 MJ/(N m3). The gross efficiency of the micro gas turbine depends on the output power but not on the gas heating value, within our estimated measurement accuracy of about 2%. Above 70% of full power, NO emission is 5 times lower than that allowed by Dutch or German legislation, and C...

Failure of a screw in a helicopter fuel-control unit: Was it the cause of a fatal crash?

Investigations into a fatal helicopter crash centered around the failure of a cadmium-plated, non-conforming, steel screw in a fuel-control unit. The present study, which includes a critical evaluation of previous investigations, was undertaken with the aim of getting more definitive answers as to whether the screw failed in flight due to hydrogen-embrittlement or stress-corrosion cracking, or whether the screw failed due to liquid-metal embrittlement during a post-crash fire. Previous investigations had not resulted in any consensus regarding the mode of failure or whether the failure was responsible for the crash.

Modelling and simulation of a temperature compensation device in a fuel control unit

A model is developed for the simulation of a temperature compensation device of a gas turbine engine main fuel control unit. For this purpose the appropriate conservation laws (mass, momentum and energy) are employed. Both the effects of temperature and pressure is taken into consideration for the calculation of the thermophysical properties of the working medium in order to accurately predict the thermal expansion and contraction of the actuating mechanism. The behaviour of the system (temperature, pressure and displacement) is described by a system of ordinary differential equations which is solved using a variable step Runge–Kutta algorithm of order 5(4). A parametric study is carried out comparing the system performance for various design variables such as the liquid mass, the heat transfer coefficient and two working mediums, ethanol and acetone.

The Entomological Evidence

Abstract The primary task was to investigate and explain the source of blockage in an elbow (B2) and in other parts of the fuel supply unit recovered from the wreckage of a private airplane. A small clump of pollen associated with a disc-shaped gummy mass of plant fibers suggested that bees belonging to the family Megachilidae might have been responsible for accumulating these plant materials. Examination of other parts of the fuel control unit revealed three dead adult bees identified as Osmia gaudiosa Cockerell (Megachilidae) and a single dead individual of the genus Ashmeadiella (Megachilidae). A survey of the tubing of a heater that had been stored showed that 69% of its tubings and fittings contained nest material and other arthropod debris including those of Ashmeadiella meliloti (Cockerell) and Anthidium sp. (Megachilidae). Through SEM examination, a single branched hair partly embedded in the clump of pollen was matched with the postgenal hairs of an adult Ashmeadiella. These facts left no doubt that the B2 elbow mass was part of a nest of Ashmeadiella. This conclusion was consistent with the facts that the wreckage had been available to the bees for nesting during the entire time of the spring and summer nesting season, and that the plant materials (leaves of Sphaeralcea and pollen sources) were readily available near the storage yard during that time. Contamination of the wreckage by nesting bees was obviously a post-crash phenomenon. Plant materials as well as dead bees would have been consumed by the intense fire that accompanied the crash if they had been present before.

The Formal Verification of Safety-critical Assembly Code

This paper describes the use of the SPADE static analysis and verification tools to model, analyse and formally verify the LUCOL assembly code modules used in the fuel control unit of the Rolls-Royce RB211-524G jet engine. This is probably the first tool-supported formal proof of correctness of safety-critical assembly code in the U.K. The work described is further novel in a number of aspects: the construction of a rigorous model of Z8002 assembly code amenable to analysis and formal verification by SPADE, the rapid development in Prolog of a translator from Z8002 assembly code to FDL (SPADE’s modelling language), the formalisation of the written specifications provided into pre- and post-conditions expressed in first-order predicate calculus, and the use of the SPADE Proof Checker to carry out the proofs of correctness.

Month in the Patent Office

In a helicopter rotor comprising a propulsion unit mounted at the tip of each blade, each unit including rotating masses subject to gyroscopic reaction forces tending to alter the attitude of the propulsion unit, means are provided for applying a force to the unit in opposition to the gyroscopic forces, the magnitude of the opposition force being varied in accordance with changes in the rotative speed of the rotating masses. The invention is described for a two‐bladed rotor wherein each blade 14 which is mounted for conventional pitch‐changing and flapping movements, comprises a spar 13 formed at its tip with a yoke 21 which supports a gas‐turbine engine 19. The engine carries rearwardly extending arms 32 which terminate in brackets 33 forming pivots for a control surface 31 located in the stream for propulsion gases from nozzle 26. The surface 31 has an arm 34 connected by a link 35 to a power element 36 which is controlled by an engine fuel control unit 37 adjusted by the pilot through a linkage 39 to vary the fuel supplied to the engine (and thereby the engine speed) from a fuel line 38. The rotating compressor and turbine of the engine exert gyroscopic forces which apply a positive pitching moment to the engine and this is counter‐acted by increasing the incidence of surface 31 with an increase in fuel supply where the surface, through arms 32, applies an opposing negative pitching moment to the engine. The adjustment of the surface may be made responsive directly to the speed of rotation of the engine or to twisting stresses applied to the spar 13.