The task was to deliver a solution that could be implemented in today’s production of the FH truck. To make the project successful it was most important that the end result had a high maturity level. For that reason an analysis of ergonomic, laws and regulations, and possible materials where conducted. To show that this project is profitable and can be realized a ruff cost estimated of material and tools is added to the research. By doing smart material choices and not changing more than necessary existing part or for that matter add more parts the outcome is more economic then if the whole ingress module is change. Catia V.5 is used as a construction program and the built-in FEA module (Finite Element Analysis) to check the strength of the construction. This is done to see that the product withstands the applied force from a person. The project result is a updated version on the ingress module where the footboard is easily change without having to remove any parts of the module. What has happened is that the footstep is divided in to two parts, one frame that’s mounted on the chassi on the truck and one footboard that is mounted on the frame. That meant that the plastic cover hade to be change as well as the footsteps. The assembly line for this new ingress module is almost identical to what it is today besides the footboard that’s added. The weight has been reduced with 15 % without doing any bigger changes on the assembly line or adding cost (if not counting for new tools).

The ingestion of hot mainstream gas into the wheel-space between the rotor and staler discs is one of the most important internal cooling problems for gas turbine designers. To solve this problem, engineers design a rim seal at the periphery of wheel-space and direct a sealing flow from the internal cooling system to prevent ingress. The main aim of this thesis is to build a simple computational model to predict the scaling effectiveness of externally-induced ingress for engine designers. The axisymmetric model represents a gas turbine wheel-space and provides useful information related to the fluid dynamics and heat transfer in the wheel-space. At the same time, this model saves much computation time and cost for engine designers who currently use complex and time-consuming 3D models. The- computational model in this -thesis is called the prescribed ingestion model. Steady simulations are carried out using the commercial CFD code, ANSYS CFX with meshes built using ICEM CFD. Boundary conditions are applied at the ingress inlet of the model using experimental measurements and a mass-based averaging procedure. Computational parameters such as rotational Reynolds number, non-dimensional sealing flow rate and thermal conditions on the rotor are selected to investigate the fluid dynamics and heat transfer at typical experimental rig operating conditions. Different rim seal geometries arc investigated and results are compared with experimental data. In addition to the prescribed ingestion model, two typical axisymmetric rotor-stator system models without ingress arc established. The aim of these rotor-stator models is to investigate the fluid dynamics and heat transfer of the wheel-space in the situation without ingress. The effects of geometry and turbulence model also arc studied in these simulations. Most results from these simulations are in good agreement with experimental data from the literature, which enhances confidence in the prescribed Ingestion model.

A combination of 3-D and 2-D computational fluid dynamics (CFD) modeling as well as experimental testing of the labyrinth seal with hexagonal honeycomb cells on the stator wall was performed. For the 3-D and 2-D CFD models, the hexagonal honeycomb structure was modeled using the concept of the baffle (zero-thickness wall) and the simplified 2-D fin, respectively. The 3-D model showed that even a small axial change of the tooth (or honeycomb wall) location, or a small circumferential change of the honeycomb wall location significantly affected the flow patterns and leakage characteristics especially for small tooth tip clearance. Also, the local details of the flow field were investigated. The seven basic procedural steps to develop a 2-D axisymmetric honeycomb labyrinth seal leakage model were shown. Clearly demonstrated for varying test conditions was the 2-D model capability to predict the 3-D honeycomb labyrinth flow that had been measured at different operating conditions from that used in developing the 2-D model. Specifically, the 2-D model showed very close agreement with measurements. In addition, the 2-D model greatly reduced the computer resource requirement needed to obtain a solution of the 3-D honeycomb labyrinth seal leakage. The novel and advanced strategy to reduce the turbine ingress heating, and thus the coolant requirement, by injecting a “coolant isolation curtain” was developed numerically using a 3-D CFD model. The coolant isolation curtain was applied under the nozzle guide vane platform for the forward cavity of a turbine stage. Specifically, the isolation curtain serves to isolate the hot mainstream gas from the turbine outer region. The effect of the geometry change, the outer cavity axial gap clearance, the circumferential location of the injection curtain slot and the injection fluid angle on the ingress heating was investigated. Adding the chamfer to the baseline design gave a similar or higher maximum temperature T* max than did the baseline design without chamfer, but implementation of the injection curtain slot reduced substantially T* max of the outer region. In addition, a more desirable uniform adiabatic wall temperature distribution along the outer rotor and stator surfaces was observed due to the presence of the isolation curtain.

The double ended guillotine break leading to density-driven air ingress has been identified as a low probability yet high consequence event for Very High Temperature Reactor (VHTR). The lower plenum of the VHTR contains the core support structure and is composed of graphite. During an air ingress event, oxidation of the graphite structure under high temperature conditions in an oxygen containing environment could degrade the integrity of the core support structure. Following this large break, air from the reactor containment will begin to enter the lower plenum via two mechanisms: diffusion or density driven stratified flow. The large difference in time scales between the mechanisms leads to the need to perform high fidelity experimental studies to investigate the dominant the air ingress mechanism. A scaled test facility has been designed and built that allows the acquisition of velocity measurements during stratification after a pipe break. A non-intrusive optical measurement technique provides full-field velocity measurements profiles of the two species Particle Image Velocimetry (PIV). The data allow a more developed understanding of the fundamental flow features, the development of improved models, and possible mitigation strategies in such a scenario.Two brine-water experiments were conducted with different break locations. Flow fronts were analyzed and findings concluded that the flow has a constant speed through the pipe after the initial lock exchange. The time in which the flow enters the lower plenum is an important factor because it provides the window of opportunity for mitigation strategies in an actual reactor scenario. For both cases the flow of the heavier density liquid (simulating air ingress from the reactor containment) from the pipe enters the reactor vessel in under 6 seconds. The diffusion velocity and heavy flow front of the stratified flow layer were compared for the SF6/He gas case. It is seen that the diffusion plays less of a role as the transport mechanism in comparison to the density-driven stratified flow since the velocity of the diffusion is two orders of magnitude smaller than the velocity of the stratified flow mechanism. This is the reason for the need for density-driven stratified flow investigations following a LOCA. These investigations provided high-quality data for CFD validation in order for these models to depict the basic phenomena occurring in an air ingress scenario.

Two topics from nuclear engineering field are included in this dissertation. One study is the air-ingress phenomenon during a loss of coolant accident (LOCA) scenario, and the other is a 5-by-5 bundle assembly problem under a design of PWRs. The objectives are to investigate the Kelvin-Helmholtz instability of the gravity-driven stratified flows inside a coaxial pipe and the effects caused by two types of spacers at the downstream of the rod bundle problem. Richardson extrapolation is used for the grid independent study. Simulation results give good agreements with the experiments. Wavelet analysis and Proper Orthogonal Decomposition (POD) are used to study the flow behaviors and flow patterns. For the air-ingress phenomenon, Brunt-Vaisala frequency, or buoyancy frequency, predicts a frequency of 2.34 Hz, which is confirmed by the dominant frequency of 2.4 Hz obtained from the wavelet analysis between times 1.2 s and 1.85 s. For the rod bundle study, the dominant frequency at the center of the subchannel is given as 2.4 Hz with a secondary dominant frequency of 4 Hz and a much minor frequency of 6 Hz. Generally, wavelet analysis has much better performance than POD in the air-ingress phenomenon that is a strongly transient scenario; they both appropriate for the rod bundle study. Based on this study, when the fluid pair in a real condition is used, the time which air intrudes into the reactor is predictable.

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The purpose of this thesis is to, on Volvo Truck’s account, look at a new concept for the construction ingress used on construction vehicles which have a higher ground clearance than ordinary trucks. The high ground clearance makes it hard for the driver to reach the first instep and therefore a construction ingress is assembled below the stationary insteps. It is designed in a way that avoids damage if colliding with objects. The present construction ingress used is too expensive, too complex and a bit unsteady to climb on. There is also a new construction vehicle being developed and the old ingress might not fit the new truck. The concept generation is carried out using systematic concept development. There are many demands and requests for the ingress and these are summarized in a design criterion list. All wished-for properties can not be fulfilled for the simplest ingress designs since they conflict with each other, for example flexibility and stability. The concepts that are generated are evaluated and selected through different matrices until one concept is found to be the most promising. Different designs of this concept are discussed and one is chosen as the most suitable. The chosen concept design is already used by at least two competitors and that confirms its suitability. The detailed design presented is only a suggestion for a new construction ingress. Before manufacturing the design needs to be analysed more accurately and the strength, material and cost need to be optimized. The analyses made in the project only show that the design is realistic and that it is worth further work. The final design is promising since it is stable to use, consists of only a few simple parts and will be cheap to manufacture.

<p>The purpose of this thesis is to, on Volvo Truck’s account, look at a new concept for the construction ingress used on construction vehicles which have a higher ground clearance than ordinary trucks. The high ground clearance makes it hard for the driver to reach the first instep and therefore a construction ingress is assembled below the stationary insteps. It is designed in a way that avoids damage if colliding with objects.</p><p>The present construction ingress used is too expensive, too complex and a bit unsteady to climb on. There is also a new construction vehicle being developed and the old ingress might not fit the new truck.</p><p>The concept generation is carried out using systematic concept development. There are many demands and requests for the ingress and these are summarized in a design criterion list. All wished-for properties can not be fulfilled for the simplest ingress designs since they conflict with each other, for example flexibility and stability.</p><p>The concepts that are generated are evaluated and selected through different matrices until one concept is found to be the most promising. Different designs of this concept are discussed and one is chosen as the most suitable. The chosen concept design is already used by at least two competitors and that confirms its suitability.</p><p>The detailed design presented is only a suggestion for a new construction ingress. Before manufacturing the design needs to be analysed more accurately and the strength, material and cost need to be optimized. The analyses made in the project only show that the design is realistic and that it is worth further work. The final design is promising since it is stable to use, consists of only a few simple parts and will be cheap to manufacture.</p>

This thesis experimentally investigates the phenomenon of ingress through gas turbine rim seals. The work focuses on developing experimental and numerical techniques for measuring the required sealing flow levels to purge the wheel-space against ingress and the effect of externally-induced ingress on the surface temperature as well as heat transfer to the rotor. Ingress is driven by a pressure difference between the mainstream annulus and wheel-space cavity resulting from the asymmetric external pressure profile in the annulus and/or the rotation of fluid in the rotor-stator wheel-space cavity. It can be prevented by pressurising the wheel-space through the supply of sealant flow. The University of Bath had measured and shown, for the first time, the thermal effects of ingress on the rotor in the wheel-space for a datum seal (axial-clearance seal) using thermo-chromic liquid crystal. However, as the previously used experimental technique with thermo-chromic liquid crystal was prone to large uncertainties, a non-intrusive temperature measurement technique using an infrared (IR) temperature sensor was developed. The new technique was successfully applied to the Bath one-stage gas turbine test facility and provided a full temperature history of the rotor surface in a transient heat transfer experiment. Moreover, a data analysis method appropriate for transient experiments using the IR temperature measurement technique was developed. The method was used to accurately calculate the heat transfer coefficient and the adiabatic surface temperature based on the full temperature history. A series of numerical experiments was carried out to develop the analysis method and the results from the numerical experiments were used to design new heat transfer experiments for both the 1 and 1.5-stage ingestion rigs of the University of Bath. Gas concentration measurements were made on the stator of the Bath one-stage gas turbine test rig to determine the variation of sealing effectiveness with sealant flow rate for four different seal geometries at design operational conditions. The IR temperature measurement technique was used to determine the effect of ingress on the heat transfer coefficient and the adiabatic wall temperature on the rotor of the ingestion test facility. Concurrent gas concentration measurements were made on the stator to compare the effects of ingress on the two discs (stator and rotor). Comparison between the adiabatic effectiveness on the rotor and the concentration effectiveness on the stator showed that the rotor was protected against the effects of ingress relative to the stator. The sealing air, which was drawn into the rotor boundary layer from the source region, thermally buffered the rotor against the ingested fluid in the core. Subsequently, a thermal buffer ratio hypothesis was developed and shown to be in good agreement with the experimental data. A previously published orifice model was modified so that the sealing effectiveness determined from the concentration measurements in a rig could be used to determine the effectiveness based on pressure measurements in an engine. There was good agreement between the effectiveness acquired from pressure measurement determined using the theoretical model and the sealing effectiveness determined from concentration measurements. It was also shown how parameters obtained from measurements of pressure and concentration in a rig could be used to calculate the sealing effectiveness in an engine.