To combat adhesion loss, sand is fired into the wheel/rail contact via a hose using compressed air typically from a storage hopper mounted to the under frame of the train. Many passenger trains in the UK are fitted with stepped braking controllers which range from 1 to 3 with a 4 th 1]. According to GM/RT2461, [2], from brake step level 2 upwards, sand is fired automatically if wheel-slip is detected. Sand is automatically fired when the emergency brakes are applied irrespective of whether low adhesion/wheel slip has been detected [2]. For adhesion loss in traction, sand can be Current railway standards [2] govern the maximum permissible sand flow rate to protect against impact wheel/rail isolation on track circuits, but do not address the hose position. This results in a range of hose setups across different train types, some of which may not be effective at delivering sand. The work here was carried out using a full-scale laboratory rail-wheel test machine to find the position for the hose and sand flow rates that give optimum sand entrainment to the contact. It was found that ideally the hose should be aimed at the rail or nip and be as close to that contact as safely possible. The use of a 20mm bore nozzle on the end of a 25mm bore hose increased sand passing through the contact by up to 70% relative to widely used 25mm bore hoses without a nozzle. Reduction in sand flow rate below the 2 kg/min threshold significantly reduced the amount of sand entering the contact. It was also shown that relatively small movements in the hose/nozzle from its ideal position and cross winds significantly reduced sand entrainment.

Various nose cowl internal geometry designs have been investigated in a study relating to the effect of hot air mass flows in the prevention of ice formation on the external nose cowl (lipskin) surfaces of aero-engine intakes. Significant differences in the lipskin surface temperature levels were observed as the internal, hot, anti-icing air distribution geometry was altered. A double-skinned arrangement (in which the hot air was closely confined to the region requiring protection against ice formation) was observed to be particularly advantageous in this respect. The effectiveness of this design was matched however by a conventional “piccolo” pipe distribution system whilst the remaining two internal Builds investigated were found to be not as effective. In evaluating the benefits that accrue from a particular design, factors such as weight, cost, reliability, maintenance and in-service experience must also be considered.

Anti-icing air from the internal nose cowl regions of aircraft engines exits via an exhaust slot to join the engine intake air upstream of the compressor. It is important that this still hot air be used efficiently downstream of the exhaust slot to effect heating of the downstream surface (acoustic liner) to facilitate the prevention of ice build-up at this point. To this end, various exhaust slot geometry designs have been investigated in an experimental study to provide guidelines to assist in this aim. The most significant variables were found to be assembly length, slot depth, exit plane width and exhaust angle. Surface heating effectiveness does not appear to be affected by “blowing ratio” differences between exhaust geometries. Equations are derived and suggested to predict the skin temperature decay downstream of the exhaust slot for a range of “blowing ratios” but the benefits in anti-icing performance must be considered ultimately against weight, cost, reliability, maintenance factors and in-service experience.

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This paper is focused on the control-related problems of a staged combustion system for a large civil high-bypass ratio engine. Methods to obtain optimal fuel distribution and an analysis of the fuel distribution control system are presented in the paper. Additionally, an overview of a closed-loop control scheme based on AFR estimation is described.