Search results

This paper aims to improve the previous fuel scrubbing model and find out the relationship between bubble diameter and scrubbing efficiency (ƞ).

A fuel tank scrubbing test bench was established to verify the accuracy of this model. Ullage and dissolved oxygen concentration were measured, and images of bubble size and distribution were collected and analyzed using image analysis software.

The bubble diameter has a great influence on ullage and dissolved oxygen concentration during the fuel scrubbing process. The scrubbing efficiency (ƞ) has an exponential relationship with bubble diameter and decreases rapidly as the bubble diameter increases.

The variation of the ullage and dissolved oxygen concentration predicted by this model is more accurate than that of the previous model. In addition, the study of bubble size can provide a guidance for the design of fuel scrubber.

This study not only improves the previous fuel scrubbing model but also develops a method to calculate scrubbing efficiency (ƞ) based on bubble diameter. In addition, a series of tests and analyses were conducted, including numerical calculation, experiment and image analysis.

The objective of this study is to model the propagating front in the interaction of gases in an aircraft fuel tank. To this end, we introduce a nonlinear parabolic operator, for which solutions are shown to be regular.

The authors provide an analytical expression for the propagating front, that shifts any combination of oxygen and nitrogen, in the tank airspace, into a safe condition to avoid potential explosions. The analytical exercise is validated with a real flight.

According to the flight test data, the safe condition, of maximum 7% of oxygen, is given for a time t = 45.2 min since the beginning of the flight, while according to our analysis, such a safe level is obtained for t = 41.42 min. For other safe levels of oxygen, the error between the analytical assessment and the flight data was observed to be below 10%.

The interaction of gases in a fuel tank has been little explored in the literature. Our value consists of introducing a set of nonlinear partial differential equations to increase the accuracy in modeling the interaction of gasses, which has been typically done via algebraic equations.

Determining the variation law of the oxygen concentration in the ullage space of the fuel tank is the key to the design of the inert system. Among various factors affecting the oxygen concentration in the ullage space of the fuel tank, the temperature difference between day and night shows particular importance while relevant analysis and calculation are scarce.

This study establishes a theoretical simulation model of the central wing fuel tank of an aircraft according to the relevant provisions of day-night temperature variation in FAR25 airworthiness regulations, verifies the model with the existing experimental data and discusses the corresponding relationship between the oxygen concentration in the ullage space of the fuel tank and the day-night temperature difference. The influence of day and night temperature difference, fuel type, fuel load rate, initial oxygen concentration, dissolved oxygen evolution and other factors on the oxygen concentration in the ullage space of the fuel tank were analyzed, and the limit of initial oxygen concentration of the fuel tank before the shutdown at night meeting the requirements of the airworthiness provisions was proposed.

The results show that the temperature difference between day and night, fuel load rate, initial oxygen concentration and other factors have different effects on the oxygen concentration in the ullage space of fuel tank. The initial oxygen concentration limit before shutdown shall be 2% below the 12% oxygen concentration stipulated by FAA.

The research results in this paper will be of good reference value to the design of the inert system and the calculation of the flammability exposure evaluation time. This paper aims to be good reference of the design of the inert system and the calculation of the flammability exposure evaluation time.

The research results of this paper can provide practical guidance for the current civil airworthiness certification work.

ICI Petrochemicals Division has appointed the Cargo Fleet Chemical Co. Ltd. (CFC) of Harrogate as official U.K. distributor for the Ethoxol and Diethoxol range of glycol ethers and glycol ether acetates which are produced at Billingham.

The efficiency of cleaning of flux residues after various periods of ageing was assessed by measuring the ionic contamination removed in an Ionograph 500 SMD. The flux residues were removed from bare boards, and boards with through hole and surface mount components. The effect of different ageing temperature was also investigated. The work has shown that there is a maximum time interval following assembly during which cleaning should be carried out. The ionic contamination of aged assemblies with through hole and surface mount components were cleaned with varying efficiencies. The surface mount components were more difficult to clean. The use of brushing and scrubbing proved particularly beneficial for the through hole components. A proprietary cleaner proved more effective than the generic alternatives considered.

THE bulk of our hospitals, etc., were built about a century ago and when examined in the light of present‐day needs and future requirements they are found to be far from satisfactory. Millions of hours are wasted annually due to the inadequacies of the buildings, equipment and management. Most of these institutions are trying to give a more comprehensive service to a volume of patients twice as large as they were originally designed to accommodate.

“Pressure polymers” is a convenient short name for vinyl acetate‐ethylene, and vinyl acetate‐ethylene‐vinyl chloride copolymers; the use of ethylene in particular necessitates operating the polymerisation reaction at appreciable pressures, in some cases up to 200 atm. However, the use of pressure in emulsion polymerisation is not an end in itself, interesting though the chemical and engineering challenge has proved to be: the development has arisen from the search for paint media with the best balance of cost and efficiency. Our first experimental vinyl acetate‐ethylene emulsions were shown at the 1966 OCCA Technical Exhibition; one of these grades has been in use on a limited scale for some years, and is now in bulk production at our Warrington factory, which began operating in October 1974. We subsequently undertook work on copolymers and terpolymers involving vinyl chloride, and bulk production of selected products has now started at Warrington.

Cleaning: achieving substantial cost reductions. John Wilkins, a cleaning machine designer, argues that major savings can be made by improving the efficiency of the whole cleaning operation — both in terms of choosing appropriately designed equipment and in using the correct management techniques.

Health and safety regulations apart, there are sound economic reasons for keeping the workplace clean and tidy — and a comprehensive range of products and services to meet the need.