bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using advanced modelling techniques to reduce the cold spillage from retail display cabinets into supermarket stores to maintain customer comfort
Authors: Foster A M , Quarini G L 
Published: October 2002

Chilled foods are increasingly popular on supermarket shelves. For marketing reasons, chilled products are displayed in retail display cabinets where there is no physical barrier between the customer and the product. Cold air from the cabinet falls out of the cabinet on to the floor, causing the customer's feet to become cold, commonly known as the ‘cold feet’ effect. The Ministry of Agriculture, Fisheries and Food (MAFF) funded a 3 year project to study the effects of retail display cabinets on supermarket store environments using experimental measurements and computational fluid dynamics. This paper provides an overview of the work and its findings. Initially a computer model of the whole sales area of a supermarket store was numerically modelled. This proved to be too large to model small detail in the store and the time taken for convergence of the solution was too long to carry out many ‘what if’ scenarios in a limited time. A smaller, more detailed model looking at just the coldest aisle (chilled produce aisle) was produced. This model was a good simulation of three different stores measured. The model was then used to predict the effect of different ventilation systems and did so with varying degrees of accuracy.
A production planning and design model for assessing the thermal behaviour of thick steel strip during continuous heat treatment
Authors: Morris W D 
Published: October 2002

This paper presents a theoretical model to determine the temperature variation of steel strip as it passes through a continuous-cooling line. The model permits the temperature along the strip to be determined and includes the effect of strip thickness to be taken into account. The model may be used in three ways. These are: to determine the strip temperature distribution having specified the external surface heat transfer coefficient as a boundary condition and hence to specify the required length of the cooling line and the nature of the cooling technology appropriate to the thermal duty required to examine the effect of changing operational parameters, such as the strip thickness and line speed, on an existing cooling line so that required production rates are matched to the thermal characteristics of the line and to specify the distribution of the heat transfer coefficient along the cooling line in order to achieve a metallurgical prescribed timewise cooling history. The paper includes a set of examples that illustrate these applications of the model.
Calculation of instantaneous sections in multi-axis milling
Authors: Vantomme P , Deprez P , Lefevre C , Castelain J M 
Published: October 2002

Multi-axis milling is a technique that enables numerous machining applications, and in particular the finishing of complex surfaces (machining of moulds, matrices and prototypes). The high operational cost of multi-axis milling drives the suppliers of CAM software to develop simulation machining programs. Today, simulation machine tools integrate the ideas of trajectory and collision, but do not take into account the calculation of cutting speeds and cutting forces, or the calculation of stresses. This paper is about the calculation of instantaneous sections in multi-axis milling, in order to model the cutting forces. All the models used to date have been formed on the principle of two circles set over from the feed movement by tooth for the calculation of the instantaneous section. For this study, the real travel of the tooth, which is a cycloid, will be taken into account.
Techniques for modelling the frequency of explosions on offshore platforms
Authors: Foster K J , Andrews J D 
Published: October 2002

This paper describes a scheme by which the explosion frequencies and resulting overpressures can be predicted for modules on an offshore platform. Given a leak of gas, the success and failure of the isolation, blow-down and deluge systems, which are designed to activate following a leak to mitigate the consequences, are considered. The frequency of each possible response to the leak is predicted using a conventional event tree and fault tree approach. Each scenario has a potential escape inventory, which together with the hole size distribution provides the escaping mass flowrate. Once the flowrate into the module is established, the wind conditions are used to determine the gas in air concentration build-up. The concentration profile with respect to time is linked to the ignition source probabilities, from which calculations can be made to assess the likelihood that an explosion will occur within a specific concentration range. The initial models assume that the gas concentration at any specific time is uniform within the locality of the leak. The work presented in this paper proposes an approach that determines the explosion probability dependent on the volume fraction of gas within the module and the likelihood of encountering an ignition source.
A non-dimensional method to increase the accuracy of turbine flowmeters
Authors: Cuthbert M R , Beck S B M 
Published: October 2002

Turbine flowmeters are inherently non-linear at low flowrates. A computer can, however, correct this non-linearity. The most common method of linearization currently used is based on a graph of the K factor (transducer pulses per litre) against the flowrate. This method is only accurate for the fluid properties for which the meter was calibrated. The accuracy deteriorates substantially if oil of a different viscosity, or the same oil at a different temperature, is used. This paper reports a new method of compensating for changes in viscosity over a large range. Tests on three sizes of flowmeter were carried out, using oil and water. Two dimensionless groups, modifications of the well-known Strouhal and Reynolds numbers, were used to produce plots of the data. The results were shown to compensate for changes in viscosity and also removed some of the underlying dimensional differences between the different turbines. The resulting sixth-order polynomial is used for flowmeters of different sizes, but with a different set of coefficients for each. The final result provides both a more versatile and a more portable method of linearizing turbine flowmeters.
Optimizing the design of waveplates for gas-liquid separation
Authors: Wilkinson D 
Published: October 2002

Waveplate separators remove liquid sprays from a gas stream by directing it round small-radius bends in narrow ducts. Such separators are generally compact with quite low pressure loss and are effective at removing drops larger than about 5 μm diameter. The performance of plain waveplate separators has been assessed in terms of the collection efficiency, the pressure loss across the separator and the separator size. Experimental data were correlated using empirical descriptions of waveplate operation based on simple theory and existing correlations for duct flows. Using these relationships, a method to optimize designs of plain waveplate separator in terms of pressure drop has been devised and demonstrated. It was concluded that the optimum waveplate separator design has three bends of approximately 33°, 66° and 33° with a duct width-side ratio of 0.094 based on experimental measurements made in air-water systems.
Contact mechanics analysis of measured wheel-rail profiles using the finite element method
Authors: Telliskivi T , Olofsson U 
Published: October 2002

A tool has been developed for contact mechanics analysis of the wheel-rail contact. Using measurements of wheel and rail profiles as input, the tool is based on the finite element (FE) code ANSYS. Traditionally, two methods have been used to investigate the rail-wheel contact, namely Hertz's analytical method and Kalker's software program Contact. Both are based on the half-space assumption as well as on a linear-elastic material model. The half-space assumption puts geometrical limitations on the contact. This means that the significant dimensions of the contact area must be small compared with the relative radii of the curvature of each body. Especially in the gauge corner of the rail profile, the half-space assumption is questionable since the contact radius here can be as small as 10 mm. By using the FE method (FEM) the user is not limited by these two assumptions. The profile measurement system Miniprof was used to measure the wheel and rail profiles that were used as input when generating the FE mesh. As a test case, a sharp curve (303 m radius) in a unidirectional commuter train track used by X1 and X10 trains was chosen. The results of two contact cases were compared with the results of the Hertz analytical method and the program Contact. In the first contact case the wheel was in contact with the rail gauge corner. In the second case the wheel was in contact with the rail head. In both contact cases Hertz and Contact presented very similar results for the maximum contact pressure. For the first contact case, a significant difference was found between the FE method and the Hertz method and the program Contact in all of output data. The Hertz and Contact methods both presented a maximum contact pressure that was three times larger (around 3 GPa) than the FE solution. Here, the difference was probably due to the combination of both the half-space assumption and the elastic-plastic material model. For the second contact case, there was no significant difference between the maximum contact pressure results of the three different contact mechanics methods employed.
An analysis of the development of the tramway/light rail concept in the British Isles
Authors: Souter I. A. 
Published: October 2002

During the first quarter of the twentieth century the electric tramcar was the dominant mode of local transport in the urban areas of this country. Thereafter, this position was ceded such that by the 1960s tramways had practically disappeared, a rate well in advance of experience elsewhere. Interest in light rail reappeared in the 1970s and six new systems are now in service. The first stage of tramway decline was brought about by the continual loss of revenue to service a variety of statutory and planning obligations imposed on operators. The second stage came in the 1920s when financially weakened operators had to renew assets in a climate of changing transport demands and economic conditions. Increasingly, as roads and road vehicle technology improved and population spread, the cost-effective option was to convert to motorbus or trolleybus. The transfer of learning from first generation tramways has been minimal and conditions for light rail development remain difficult although the government is becoming more interested. The easing of legislation governing establishment and operation of light rail services is essential for future expansion, and will be best achieved by the industry finding a voice to speak with authority on its behalf.
Phototube sensor for monitoring the quality of current collection on overhead electrified railways
Authors: Bruno O , Landi A , Papi M , Sani L 
Published: October 2002

A new measurement system able to detect the occurrence of arcing between the pantograph and the overhead contact line was studied and set up. The system uses photomultiplier tubes to measure the duration of the ultraviolet emission due to electric arcing. The major advantages of the system proposed are its non-invasivity with respect to the pantograph equipment, its reliability and its low cost. Correlation with data acquired during high-speed test runs from different sensors (e.g. currents measured in an equipotential wire between the front and the rear pantographs, images acquired from a TV camera), provided the opportunity to perform an efficient calibration and an analysis of selectivity of the phototube sensor. Data from the phototube sensor along with various other information lead to the definition of a reliable index for evaluating the quality of the current collection. The determination of such an index has primary relevance for maintenance activities, for computing the minimal thrusts to be applied to the pantograph at different speeds and for testing new materials for overhead contact wires and collector strips.
Shared track—A new dawn?
Authors: Griffin T 
Published: October 2002

Shared track is now a possibility in the United Kingdom; the Sunderland Metro will introduce lightweight vehicles on to the Railtrack network. On the other hand, some cities that pioneered the concept are now developing systems where light rapid transit (LRT) and heavy rail are kept separate. This paper examines the technical issues behind these developments. It also examines the scope in the United Kingdom for the wider applications being seen elsewhere in Europe. Innovative approaches are essential if rail systems are to continue to play a role in short distance passenger transport. Shared track could merge the best of heavy rail and tramway practice to create extremely attractive services, taking advantage of new traction options. The main technical challenge is to create vehicles that are both commercially attractive and meet the safety requirements that apply on those parts of the various systems where they might operate.
Train-generated sound within an underground light railway system
Authors: Lilley D. M. 
Published: October 2002

An empirical study has been made to identify important features of sound levels generated within an underground section of a light railway. Measurements of sound pressure level were recorded as trains passed within a few metres of computer-controlled instrumentation during normal daytime operation. Peak values of sound pressure level were identified for each passing train and a method of compensating for train speed was investigated. Further measurements were taken of sound levels as two Metro trains were repeatedly driven through the same section of underground track at different nominal speeds during a night-time possession. Characteristics of sound levels produced by approaching and departing trains have been studied to identify any salient features that may be beneficial in developing a means of monitoring the condition of passing trains. No definitive relationship was identified between train speed and peak value of sound pressure level, although results indicated that higher sound exposure levels and duration when a passing train generates sound levels above a threshold value can be linked to train condition. Further development of the work is planned to provide an automated management tool for identifying trains in need of further inspection and maintenance. The ultimate aim is to improve the efficiency of scheduling for train maintenance and to satisfy environmental needs for keeping train-generated sound to minimum levels.
Transition detection for laminar flow aircraft using microphones beneath the surface of laser drilled suction panels
Authors: Barrett R V 
Published: October 2002

The possibility of detecting transition through the very small laser drilled perforations in panels representing the suction surface of a hybrid laminar flow aircraft is examined. The method uses miniature microphones to detect changes to the noise received from the boundary layer. Tests using a flat plate rig in a low-turbulence wind tunnel at Reynolds numbers up to 3.8 million per metre, demonstrate that the boundary layer state can be defined in this manner, most simply through measurement of the root mean square (r.m.s.) of the microphone signal. It is shown that the r.m.s. reaches a peak in the transition zone and that when the boundary layer is fully turbulent the value is still significantly higher than it was before transition. Porosity in the range 0.8-6.4 percent was examined, with nominal hole diameters of 0.06 and 0.10 mm in 0.9 mm thick laser drilled suction surface specimens. Suction flow through the surface was found not adversely to affect the operation of the system. The experiment was limited to low Reynolds numbers because the high background noise in the wind tunnel made detection of the boundary layer element of the signal increasingly difficult to define as speed increased. It is considered that test in flight will be needed to prove fully the validity of the method. A preliminary design of an installation for this purpose is suggested that allows the suction flow to be maintained over the measuring region.
A three-dimensional finite element investigation of the bolt stresses in an aero-engine Curvic coupling under a blade release condition
Authors: Richardson I J , Hyde T M , Becker A A , Taylor J W 
Published: October 2002

Curvic couplings transmit torque between parallel in-line shafts or turbine/compressor discs. They are used extensively within the aero-engine industry but can also be found in industrial gas turbines. The manufacture of Curvic couplings involves the precision cutting and grinding of mating teeth on the adjacent ends of the components; the assembly is then clamped together with bolts. The use of Curvic couplings in engineering transmission components is relatively widespread, although the publication of work in the open literature is currently limited. An attempt has been made to investigate the factors influencing the load imparted to a fan Curvic coupling in a large aerospace gas turbine. Owing to the very complicated nature of the current problem, some geometric and especially loading simplifications have been necessary. The results presented provide an initial solution to the problem of the three-dimensional numerical modelling of a fan Curvic coupling during a blade release event. This work is intended to provide data to help make decisions at the design stage and, together with aero-engine fan blade-off tests, will contribute to an improved design of Curvic couplings. The current work has been carried out using the three-dimensional finite element elastic-plastic contact method in an attempt to achieve realistic displacements of the fan Curvic teeth and bolts.
Reducing cost, time and risk in aero-engine compressor testing
Authors: Backhouse R , Ivey P 
Published: October 2002

There is constant pressure to reduce engine development cycles to minimize costs and bring forward the revenue earning part of the engine's life. As cost and time are designed out, the risk of performance shortfall must be minimized by bidding efficiencies from demonstrated technology. This requires a large-scale ongoing advanced development program. In compressor development, high-speed tests are unavoidable but are expensive; low-speed rigs are easier to instrument and provide a cost-effective filter for the high-speed designs. The large-scale, low- speed compressor at Cranfield is one of only four worldwide. Recent investment in data reduction software has greatly reduced the test/analysis cycle time.
Model-based reasoning for fault diagnosis of twin-spool turbofans
Authors: Baig M F , Sayeed N 
Published: October 2002

A simplified rule-based expert system can be of great use to maintenance engineers involved in on-line health monitoring of aero-engines. The development of a rule base has been done on the following lines: 1 A design and off-design mathematical model of the turbofan has been developed. 2 Healthy and fault-implanted engines have been run at various off-design conditions to see the effect of faults on certain aero-thermodynamic performance parameters, with appropriate selection of independent parameter(s). 3 From these calculated values, fault matrices have been developed for sea-level static conditions taking the net thrust as an independent parameter. 4 From these fault matrices, rules have been developed which form the knowledge core of the expert shell. These rules have been developed for Garrett TFE 731-2, a moderate bypass and overall pressure ratio, generic twin-spool turbofan and so the package (off-design code plus expert system) can serve as a pedagogical tool for training of engineers in the aero-engine industry and academic institutions.
The phenomenon of helicopter rotor blade sailing
Authors: Newman S 
Published: October 2002

Blade sailing is an aeroelastic phenomenon affecting helicopter rotors when rotating at low speeds in high wind conditions. This is a potentially dangerous blade motion and the excessive flapwise tip deflections generated endanger the airframe, the flight crew and any personnel working close to the aircraft. This phenomenon is particularly applicable to naval helicopters or those operating off exposed sights such as oil rigs. The research covered an experimental investigation into the effect of an abeam wind flow over a simulated flight deck of a Rover Class Royal Fleet Auxiliary vessel. Blade flexibility and rotor hub mechanical features were introduced into the theory and the resulting method applied to the Westland Lynx and Sea King aircraft. The semi-rigid rotor of the Lynx is relatively well controlled, but the rotor hub construction of the articulated rotor of the Sea King and the interaction with the flexing blades allow blade tip deflections to be generated of an order to strike the fuselage. The research described in the paper has led to an improved understanding of the blade sailing phenomenon. The results concur with reports of blade sailing occurrences and the operational conditions that are likely to trigger this phenomenon. The development of theoretical models may be used to assess the importance or otherwise of this effect on future rotor designs or the operational limitations of the aircraft.
Evaluation of four blood pump geometries: The optical tracer technique
Authors: Rose M L J , Mackay T G , Martin W , Wheatley D J 
Published: October 2002

Artificial blood pump assistance of the failing human heart can allow it to recover. Analysis of blood pump fluid flow is a useful tool for design development and thrombosis minimization. The aim of this study was to investigate fluid flow, particularly ventricular clearance rate and stagnation areas, in four different blood pump geometries and to determine the best design. The blood pumps consisted of a polyurethane ventricle, and combinations of inlet/outlet pipe angles and compression plate shapes. A video camera recorded the motion of fluid labelled with an optical tracer (Methyl Blue histological dye). A novel processing method was developed to produce colour maps of tracer concentration, experimentally calibrated. An overall picture of fluid flow in each pump geometry was generated by considering clearance curves, tracer concentration maps and inflow jet animations. Overall and local mixing coefficients are calculated for each pump. The best geometry featured straight inlet/outlet pipes and a domed compression plate. This optical tracer technique has proven convenient, economical, sensitive to low concentrations of tracer and provides instantaneous pictures of tracer distribution in a ventricle.