This thesis provides unique insights into the application of a geometrically induced swirl by a three-lobed helix pipe on a lean phase of particulate suspension in air along a horizontal pipe section. A series of experimental and computational studies were applied to three flow conditions employing high speed photography, Particle Image Velocimetry (PIV) and Laser Doppler Anemometry (LDA), as well as Computational Fluid Dynamics (CFD) techniques. The CFD simulation predictions were validated both qualitatively and quantitatively against the experimental data and were then used to obtain further insights into the characteristics of the flow behaviour. The LDA measurements of u, v and w velocities were shown to be in good agreement with the predicted CFD velocity components. Additional pressure loss caused by the swirl pipe was found to be proportional to the Reynolds number of the flow and increased further with an addition of particles to the swirling flow. It was concluded that the swirl pipe imparts a wall jet type swirl to both an air-only flow and a lean pneumatic flow with velocity and momentum shifts from axial to tangential closer to the wall. The cusps and ridges of the twisted three lobe surfaces were shown to create a primary flow parallel to the flow axis, and secondary flows of a circulatory motion perpendicular to the primary flow. As a result, the trajectories followed by particles were observed to be affected by their size. The generated turbulence was shown to impart higher core axial velocity for both air and particles. The swirl was found to decay proportionally with the distance downstream of the swirl pipe and inversely to the flow's Reynolds number. The major conclusions drawn from the study were that the swirl pipe locally increases the conveying velocity and produced an improved particle distribution across the downstream section of the pipe.

This study was initiated by the need to improve current techniques used in the design of pneumatic conveying systems. At present, the commonly used method to predict the pressure drop in a vertical pipeline in a pneumatic conveying system is to obtain the pressure gradient in a horizontal for the identical conveying conditions and double the pressure gradient in the horizontal pipeline to give the pressure gradient in the vertical pipeline. In addition, scaling for pipeline bore in vertical pipelines is simply undertaken by considering the change in cross-sectional area. This is another area where sufficient investigation has not been undertaken. Therefore, as part of remit of this research study into improving current design techniques, an investigation into the effect of pipeline bore in vertical conveying would also be undertaken. This thesis documents the systematic approach that was used in order to produce some usable models that may be used in improving the understanding and design of pneumatic conveying systems. The models produced were based on data obtained by testing a range of products in an industrial scale pneumatic conveying test facility. The experimental data that was obtained from the pneumatic conveying tests form the basis of the ensuing analysis. The basic experimental data, which is primarily in the form of pressure gradient data for pneumatic conveying in horizontal and vertical pipelines, is explained in detail, along with the subsequent analysis of the data.

Pipe junctions arc a regular feature of piping and pressure vessel systems and are often the subject of multiple loads. acting simultaneously and at irregular intervals. Due to the nature and complexity of the loading. the subject has received a significant amount of study from designers and stress analysts to resolve some of the difficulties in stressing pressure structures. An extensive finite element (FE) analysis was carried out on 92 reinforced buttwelded pipe junctions manufactured by the collaborating company. Spromak Ltd. After comparing the resulting effective stress factor (ESF) data with ESFs for un-reinforced fahricated tee (UFT) it was concluded that, for the majority of loads, reinforced branch outlets appear better able to contain stresses than their un-reinforced counterparts. The linear FE study was followed by the inelastic analysis of three reinforced branch junctions. The purpose of the research was to investigate the potential use of such analysis as a tool for estimating the bursting pressure of pipe junctions and satisfying customer requirement for proof of a products performance under internal pressure. Results obtained showed that small displacement analysis is unsuitable for estimating the bursting pressure of a pipe junction, whilst the large displacement results were similar to those obtained using a hand-calculation. Ultimately, the study concluded that inelastic analysis was too expensive, offering little by way of insight into the problem than could be found by using classical stress analysis techniques. Following on from the study of reinforced branch outlets, this thesis described work undertaken with British Energy Ltd. to extend their current capability of stress prediction in UFT junctions using a FE based neural network approach. Upon completion of training new neural networks, the PIPET program was tested against new, previously unseen, FE data generated for this study with good results. The program was further evaluated by comparing the output from PIPET with FE data obtained from reviewed literature. For the pressure load case, a significant proportion of the data obtained from said literature was within the PIPET predicted stress ranges. with the new version of PIPET tending to calculate slightly lower stresses than the original program. However, whilst the pressure load case comparisons proved useful, the branch bending cases showed less concordance with PIPET's predicted stress ranges.

The performance of peristaltic pumps is mainly governed by their tubing or hose materials. Research and development in this area is therefore very important for peristaltic pump manufacturers to keep in front of the competition and to open up new applications to enable further market penetration. Another aspect of this is of course price; performance and cost have to be in balance. As an approach to fabricate a new tube material, the field of negative Poisson's ratio (or: auxetic) materials is explored. The combined deformations of tensile, compression and shear in a peristaltic pump tube may well benefit from the specific characteristics of auxetic materials. Materials can be designed to keep their dimensions constant in directions perpendicular to an applied load. This is referred to as “auxetic balancing”. Finite element modelling shows that lowering the Poisson's ratio will rapidly decrease the maximum stresses in the cross-section of an occluded tube. Optimum values for the Poisson's ratio are found to be between −0.1 and +0.1, preferentially being 0. The re-entrant honeycomb structure is selected for initial trials, but manufacturing of this structure at the desired dimension proved to be too difficult at this time. Instead, electrospun nanofibre membranes are selected as the reinforcement structure. A liquid silicone elastomer is used as the matrix material. Key characteristics for the new material are derived from baseline test results on existing tubing. Laminates are manufactured from electrospun nylon6 nanofibre membranes coated with a liquid silicone rubber. Compression moulding is used to cure the nylon6-silicone rubber laminate, to give two effects: it ensures impregnation of the membrane and the compression deforms the nanofibre structure in such a way that it will become auxetic through-the-thickness. Flat sheet laminates of 2 mm thickness are manufactured with 14 layers of reinforcement. A reinforcing effect and substantial lowering of the through-the-thickness Poisson's ratio is observed for the laminates at low strains. At higher strains (>50%) the effect of the reinforcement diminishes and the Poisson's ratio of the laminate and pure silicone rubber equalises. Finally, tubular laminates are manufactured and the resulting tubes are tested in a peristaltic pump with some promising results (>1 million occlusions before failure). Tube performance is not yet at the required level, but with further optimisation of the laminating process, mould design and (post-)curing large steps forward can be made.