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Preventing ice accumulation on aircraft surfaces is important to maintain safe operation during flight. Ice accumulation on aero-engine nose cones is detrimental as large pieces may break off and be ingested into the engine damaging the compressor blades. Currently, hot bleed air is taken from the compressor and blown over the inside and outside surfaces of the nose cone to prevent ice formation on the surface. Although effective, this technique reduces the efficiency of the aero-engine. This investigation evaluates the performance of a novel anti-icing system that uses a rotating heat pipe to transfer heat from the engine to the nose cone. Rotating heat pipes are effective two-phase heat transfer devices capable of transporting large amounts of heat over small temperature differences and cross-sectional areas. In this system, waste heat that is generated in the engine would be transferred to the rotating heat pipe at an evaporator and then transferred into the critical areas of the nose cone at a condenser preventing ice accumulation on the outside surface. In this investigation, the heat is transferred into the heat pipe from a fluid heated by the engine that would pass through a small annular gap between the rotating heat pipe and a stationary wall. The heat transfer for this configuration and the effect of passive heat transfer augmentation on the outside of the rotating heat pipe in the jacket was investigated experimentally for a range of Taylor numbers of 10^6 < Ta < 5x10^7 and for axial Reynolds numbers of 900 < Re_x < 2100, characteristic of this configuration when engine lubricant was used as the working fluid. It was found that by using an array of three-dimensional cubical protrusions, the heat transfer in the evaporator could be increased by 35% to 100%. This result was better than that found using two-dimensional rib roughness. It was also found that the evaporator performance was a limiting factor in the heat transfer performance of the system under most conditions, so further optimization of the evaporator is important. In the proposed condenser design, the condenser section of the rotating heat pipe would be encased in a lightweight, high conductivity polycrystalline graphite or similar composite material and the end of the heat pipe would be in direct contact with the nose cone. It was found that the end-wall of the heat pipe was not a source of high heat transfer, however it provided an effective means for heating the tip of the nose cone. The effect of using heating channels on the inside of the nose cone was also considered. Here, the condensate from the rotating heat pipe was driven through small radially spaced channels on the inside surface of the nose cone. The heating channels were found to be ineffective due to the small contact area that could be made with the nose cone. This was a result of the limited condensate flow that occurs in rotating heat pipes. The heat transfer through the proposed system was 700W to 1100W using water and 400W to 800W using ethanol in the heat pipe. It was found that 50% to 75% of the arclength of the nose cone could be maintained above 0°C using water in the heat pipe at an ambient temperature of -30°C and an airplane speed of 300 km/h. This arclength decreased to approximately 25% when ethanol was used as the working fluid. An increase in airplane speed reduced this arclength maintained above 0°C significantly. / Thesis / Master of Applied Science (MASc)

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The impact of a pipeline by a dropped object has been considered to consist of four distinct impact components: the dropped object, pipeline protection, the soil bed and the pipeline itself. The effect of these components as energy absorbers and the effect on system response has been investigated. Quasi-static and dynamic testing has been earned out to investigate the interaction between the various impact components. Quasi-static testing has been widely used to develop initial predictions, since closer observation of interaction is easier. The validity of applying these predictions to dynamic situations has been addressed using results from dynamic impact testing. The Dropped Object: Two areas have been investigated which address the dropped object within the impact system: the dropped object's impact profile and its deformability. Testing has been carried out to study the effect of typical loading profiles. Research has shown that the dropped object profile significantly effects the pipe response; a cone shaped indentor generates deformation with far less energy than either a wedge or a patch shape. The applicability of a method to predict the interaction between two deforming structures, using a method of shared energy, has been investigated for quasi-static and dynamic loading. During quasi-static testing it was found possible to predict a combined response using individual responses. During dynamic testing prediction was not possible, since inertia effects where found to dominate the response. The Concrete Protective Coating: A programme of work carried out has qualified the role of a pipeline protective coating and assessed the effect of four different types of concrete reinforcement. Summary Although the study has not been exhaustive, it is clear that reinforcements, which hold the concrete coating to the pipe, allow the coating to continue its protection. Fibres added to a concrete mix were found to reduce the damage to the pipe. However mesh reinforcements were found to hold the concrete together most effectively and provided the greatest added protection. The Soil Support: All foundations absorb some energy. Tests have been carried out to investigate the effect of a soil bed on the response of a laterally loaded pipeline. During dynamic tests on sand supported pipes it was noted that no energy was absorbed during the initial deformation, possibly corresponding to local indentation of the pipe wall. After this the sand was seen to react and absorbed a proportion of the energy, depending on the hammer's drop height. The energy absorbed by the soil continued to increase until an energy plateau was reached, after which the soil absorbed no further energy. It was noted that the displacement at which this energy plateau was reached increased as the drop height increased. Two possible causes of the energy plateau have been discussed. The first cause questioned an assumption that the pipe would deform as if on simple supports. The second possible cause suggested a change from dynamic to quasi-static response and investigated the relationship between acceleration, velocity and reaction force. Of the possible causes of the energy plateau, the most likely is thought to be soil related. Investigation into the Deformation of Locally Loaded Pipes: The investigation into pipeline deformation has been carried out using experimental, numerical and theoretical analysis methods. Quasi-static test results have been used to investigate four pipeline parameters and their influence on energy absorbed by the pipeline, (length, L, wall thickness, t, diameter, D and material yield stress, ay). This investigation led to an empirical equation, which brought all energy-displacement (E-8) curves on to a common curve, for a wide range of these variables. This empirical relationship has been developed to predict deformation, for the range of parameters investigated. Dynamic results obtained were normalised using these empirical equations and data was seen to fall into two broad groups, one group comprising seam welded pipe and one group comprising cold drawn pipe. Strain rate effects were proposed as the most likely cause of this bi-grouping. Limitations in the experimentally derived empirical relationship have been identified, resulting from an insufficient range of pipe samples tested.

Call number: LD2668 .T4 1950 J35 / Master of Science

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In the oil and gas industry, threaded pipe connection is frequently used to connect the casing string, drill pipe strings or production and transportation risers and pipelines. The connection is normally preloaded in order to maintain a sealed and secure connection while in service and avoid leakage. Tapered thread are a common connection and in order to introduce preload to the threaded connection when they are assembled a certain make-up torque is going to be applied. The make-up torque plus external loads result in a multiaxial stress distribution over the connection, where the threaded connections act as stress risers. Environment such as waves and currents cause dynamic loads acting on the pipe line and offshore structures. The weakest point in offshore structure is the pipe connection because of fatigue crack initiated in the connection's threads. Researchers and engineers developed a variety of patented threaded pipe connection which all claiming to improve a connection's fatigue life. The experimental data for patented designs, available in literature, is limited. Most published studies usually comprise experiments on a single connection type. For detailed fatigue analysis those published studies cannot be used since there is no uniformity in testing setup, loading conditions and damage detection technique exist. Moreover, current design curves in codes and standards lead to overly conservative or inaccurate results. The aim of this work is to provide a better understanding of the fatigue mechanisms of threaded pipe connections and to study the effect of different design features on a connection's fatigue life. The final goal is to formulate guidelines for new fatigue resistant connection designs. API connection is used as a reference in this study. Several modifications and design features are applied to the connection type. To simulate the effect of these modifications, a parametric 2D axisymmetric finite element model, ABAQUS is used. 2D finite element result are compared with a 3D model to prove its validity for both make-up. In addition, the results of the 2D axisymmetric simulation are validated by static strain gauge measurements during a make-up test and an axial tension test. The validated model is then used to evaluated the influence of the connection properties and design features on the threaded connection's behaviour. Test rigs were designed to perform axial fatigue experiment on two scales: the small-scale experiments on 1" (33.4 mm outer diameter) connections are performed in axial fatigue testing, the medium scale tests on 4.5" (114.3 mm) connections are carried out under axial tension for which a setup is developed. The majority of the performed fatigue tests are small scale experiments. Several modified configurations are tested. The S-N curve is constructed, so that the effect of certain configuration on the connection's fatigue life can be quantified. The local modification of the threaded connection's geometry as well as the connection's contact condition's contact conditions can have an important influence on the fatigue life of the connection. A beach marking technique is used to visualized the crack fronts at different moments during the tests so that exact crack shape can be seen during post-mortem analysis. The result shown that a crack initiates at the root of the last engaged thread of the male part of the connection, and propagates slowly over a large segment of the circumference, forming a long shallow crack. When the crack penetrates the pipe wall, it rapidly increases in size along two crack fronts. The shape of crack observed in beach mark analysis do not have a semi-elliptical shape as commonly used in fracture mechanics. A fatigue crack growth analysis that considers the crack as an annular flaw, is effective in describing the crack growth behaviour. The experimentally obtained S-N curves and the result from the finite element simulations are combined in multiaxial damage evolution law. The observed trend in fatigue lives of the configuration are explained by using the fatigue analysis. Using a connection's thread load distribution as a measure for its fatigue life is proven to be inaccurate. The main reason for this is that the load distribution is related to axial stresses over the connection. The fatigue life of a threaded connection is determined by the local multiaxial stress distribution and strain range around the root of the last engaged thread. These local conditions are not only the result of the load distribution, but they are also affected by the hoop stress introduced during make-up, which can additionally be affected by a changed connection stiffness. The multiaxial damage evolution law is used to analyse the influence of several features on a connection's fatigue life. It is not for all patented modifications that an increased fatigue life is predicted when applied to the API connection. The final conclusion reached is that, in order to optimize a fatigue resistant connection, several design features must be combined together. The thread shape can be optimized to obtained a low stress concentration factor and reduce the local strains at the thread root. The connection's global geometry and make-up conditions can be optimized to improve the load distribution over the threads and reduce local stresses and strains at the threads.

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