Experimental fluid mechanics has for a long time been used to visualize flow phenomenon. An early pioneer was Ludwig Prandtl who used aluminum particles in water flumes to describe the flow in a qualitative manner. In line with the rapid development of Computational Fluid Dynamics, CFD, the need for new validation tools has increased. By combining Prandtls attempt to trace particles and contemporary tools in laser and computer technologies a quantitative non intruisiv whole field technique, so called Particle Image Velocity (PIV) has been developed. The PIV technique has been improved and grown in popularity through recent decades with the increase in computer capacity. This thesis describes three rather different areas of application of PIV measurements. In the first case PIV is used as pure measurement technology tool to describe the flow field inside an attraction channel in connection to fish migration. In the second case, PIV is applied as a validation tool for CFD calculations with Large Eddy Simulation (LES) including an extensive analysis of the results. Finally, a description of how PIV technique can be adopted to study the flow of complex fluids in small geometries by means of microscopy is given.The attraction channel is a U-shaped channel designed to facilitate salmonoid like fihes to migrate upstream to their spawning grounds. The attraction channel has a restriction in the downstream outlet that provides an acceleration of the attraction water up to 38% of the sourunding water velocity according to the PIV measurements. With PIV measurements it is also shown that the depth of displacement over the restriction is significant for how far downstream the acceleration is perceptible. CFD technology is constantly evolving and new methods will become the future standard in the industry. In the current situation Reynolds Avereaged Numerical Simulations (RANS) is the most used method in CFD. But development is approaching LES technology. This is, for instance, motivated by energy production units which has many applications with high turbulence and temperature fluctuations. In the current situation it is required to extend the service life of existing power plants. Therefore it is desirable to be able to estimate these fluctuations impact on thermal loads on the materials inside the plant, for example pipe walls. An LES approach is superior to applying to RANS since the large eddies are resolved. However, LES is still not mature enough to be used without validation in critical applications. Therefore, PIV has been used to create a validation database for a generic T-junction.Double Restriction Sealings (DRS) have been used in bearings and other lubricated applications since the 1940's. A DRS is intended to prevent contamination from entering and is therefore used to increase the life span of lubricated parts, i.e. hinder polutants to reach the rolling elements in bearings for example. Although it is widly applied little is known about the actual function and mechanism of the DRS. To learn more about the flow and particle tracks within a DRS, a new method to visualize and quantify grease flow within a DRS has been developed based upon micro PIV. The main result from this study is that it is possible to make quantititative measurement of the flow within a DRS.

Increasing competition has set pressure on the product development process to reduce development time and costs. Computer Aided Engineering (CAE) has been used to decrease development times by facilitating early predictions of product performances and qualities. Especially in early phases of product development, models with sufficient accuracy can provide valuable decision supports in order to pass legislations and fulfill customer expectations. Acoustic performance and sound quality are essential parts of the perceived product functionality and quality. A powerful method in product sound development is to combine recordings and simulations into auralizations. Interior vehicle noise is an important factor in the perceived product quality where tyre noise is a dominant source. The objective of this licentiate thesis was to lay the foundation for an auralization model of interior tyre noise. The aim of the model is to use the results from for example FEM simulations of tyre/road interaction and filter it through experimentally measured transfer functions into the cabin of the car. By varying compounds, components and road profiles in simulations, tyre noise can be auralized in different cars in an early design phase. Tyre noise predictions and auralizations are relevant both in tyre and car development. The vibrations generated by the tyre/road interaction are transferred through the hubs of the car and into the cabin as structure borne sound. The hub acts as the coupling element and describes the boundary condition for the rim. In paper I, the mechanical mobility of a hub was measured in 6-DOF. Measurement results showed good multiple coherences, reciprocities and low random errors in the frequency range 0-300 Hz. The measured mobilities will be used to transform operational forces and moments into velocities and will be implemented as boundary conditions in FEM simulations. For auralizations of the air-borne tyre noise contribution, knowledge of the required accuracy in positioning of sources and receivers is essential. In Paper II, variations in perceived sound caused by displacements of source and listening positions were assessed to find the smallest displacement giving a just audible differences. In addition, binaural transmissibility functions were measured from a loudspeaker near a wheel to an artificial head inside the car. Results showed that the accuracy in the positioning of the source and the receiver needed to be smaller than 2 cm to avoid audible differences. In order to generalize auralizations of interior tyre noise, audible variations in specimens of nominally identical products need to be known. In Paper III, variations in perceived interior sound between tyres of different brands and specimens of nominally identical cars were assessed. The differences between five nominally identical cars were found to be two to three times larger than the difference between two tyre models / CASTT - Centre for Automotive Systems Technologies and Testing

Fluid flow through porous media takes place in many natural processes such as ground water flows, capillary flows in plants and flow in human organs and muscles. It is also of outmost importance to have knowledge of this flow in a number of industrial processes such as paper making, making of fibre boards, composites manufacturing, filtering, forming and sintering of iron ore pellets and drying and impregnation of wood. Despite the significance of porous media flow and the vast amount of work that has been performed to investigate it, knowledge of some fundamentals is missing. Little is, for instance, known about transitional and turbulent flow in porous media on the microscopic level. On a macroscopic level Darcy law is extended to the so called Ergun or Forchheimer Equations when Re becomes larger than about 10 to fit experimental. The actual value depends both on the porous media and how Re is defined. The deviation from Darcy flow can for modest Re be explained by inertia but may, as Re increases, also be attributed to turbulence. The macroscopic way of modelling the transition from inertia dominated to turbulent flow is just to continue with the Forchheimer Equation or possibly some version of it. In any case experimental data yields that, on a macroscopic level, the transition from Darcy flow to inertia dominated and turbulent flow is smooth. To get a better understanding of this process the transition from laminar to turbulent flow in porous media is here studied with a new method. To mimic inter-connected pores, a simplified geometry is studied consisting of a pipe with a relatively large diameter that is split into two parallel pipes with different diameters. This is a pore-doublet set-up and the pressure drop over all pipes is recorded by pressure transducers for different flow rates. Statistical method and frequency analysis are performed to investigate collected data (Papers A and B). Positive skewness of pressure drop fluctuations indicates early stage of presence of turbulent patches in the flow for each pipe. The measured flow distribution and pressure drop fluctuations highlights six distinct flow patterns in the pipe network based on variation in flow regime of each pipe and the level of pressure fluctuations (Paper B). Correlation between the pressure drop between two pipes shows that two parallel pipes follow each other fluctuations much better before both of them become fully turbulent. Some detailed results are that the frequency analysis reveals two different frequency band events in the pipes. The gain factor shows that both frequency band events originate from the larger pipe until the early presence of turbulent patches in the smaller pipe (Paper B). The low frequency fluctuations makes the flow in the pipes to be out of phase while the high frequency band fluctuations try to bring the flow in the pipes back to equilibrium state.

LKAB (Luossavaara-Kiirunavaara AB) is an international company that producesiron ore products for the steel industry; their main product is iron ore pellets.The aim with this research project is to numerically investigate if it is possible to use selective non-catalytic reduction (SNCR) technologies in grate-kiln pelletizingplants for NOx reduction. The technique had, to the best knowledge of the author, never been used in this context before despite that it is commonly used in cement and waste incineration plants. The investigation is done in several stages: 1) Reveal if the technique is possible to use with the two most commonly reagents ammonia and urea. 2) Derive a chemistry model for cyanuric acid so that this reagent also can be scrutinized. 3) Compare the reagents urea and cyanuric acid in the grate-kiln pelletizing process.A CFD model of parts of the real grate was created and numerical simulations with the commercial code ANSYS CFX was carried out solving the flow field. A model for spray injection into the grate was then included in the model enabling a study of the overall mixing between the injected reagent droplets and the NOx polluted air. It is shown that the SNCR technique with ammonia does not work in the grate-kiln process. Urea on the other hand can be used under some conditions and also cyanuric acid. The results lay grounds for a continued development of the proposed chemistry model.

No description available.

Water turbines are since some years widely used for grid stabilization purposes according to their exceptional load variation capability which gives them the ability to compensate grid fluctuations initiated by the customer’s consumption or intermittent electricity production systems such as wind and solar power. Different renewable power generation technologies can be combined in mini-grids to electrify isolated villages and extend existing grid networks. In these occasions, small hydro units are also a good option to reduce the overall variability of supply to low levels and provide low‑cost, local electrification solutions. Hence, initially designed hydropower turbines for steady operation at on-design operating condition experience many off-design, start/stop and load variations during their life time according to the nowadays on-demand energy market and introduction of intermittent power generation systems to the electricity market.Start/stop and load variations can be harsh for the turbines due to the time dependent forces exerted on different parts of the turbines, especially rotating parts. Off-design performance of hydropower systems may also result in unfavorable and harmful periodic forces on the rotating parts. Therefore, investigations are required to study these working conditions and consider them in design of new hydropower plants and refurbished turbines. This was the motivation for the experimental investigation of a Kaplan turbine during on-design, off-design and transient operations with focus on the turbine’s rotor. The test case was a 1:3.1 scaled model of Porjus U9; a Kaplan turbine. The first paper deals with pressure measurements on the runner blades of the model under steady state operating conditions to find and quantify the sources of pressure fluctuations exerted on the runner at different operating points. The goal was to investigate the turbine’s performance at the best efficiency point with concentration on the performance of the water supply system and compare it to operations at high load and part load for a constant blades angle. The model results are compared with prototype measurements to corroborate the findings. The second paper presents the model investigations during load acceptance and load rejection. The model was investigated with pressure measurement on the stationary and rotating parts of the turbine under different load variations between part load, high load and best efficiency point. The third paper focuses on velocity measurements in the runner blade channels and at the runner outlet under on-design and off-design operating conditions. The velocity measurements are performed with a laser Doppler anemometry (LDA) system. The results of the model investigations along two propeller curves are presented to investigate the runner blade angle effects on the turbine’s performance.

Waste hydrochloric acid (HCl) from the pickling process at SSAB EMEA in Borl¨ange, Sweden, is regenerated using a technique called spray roasting where waste HCl is sprayed into a hot reactor through four spray nozzles at the top of the reactor. The regeneration (drying) process is driven by four natural gas burners placed symmetrically along the periphery of the reactor and causes the water in the waste acid droplets to evaporate. Through chemical reactions the iron chloride is oxidized to form hematite and chloride gas; the latter to be used for manufacturing of new HCl which anew is used in the pickling process. The produced byproduct in form of hematite is sold and used in e.g. the electronic industry and as filling material for road constructions. A good quality of the hematite powder vouch for profit of the sold product, and hence an enhanced economy for the whole regeneration process which in turn motivates a continued regeneration rather than shipping away the waste acid and continuously buying new HCl.Due to the hostile environment inside the reactor, measurements and optical visualizations are difficult to perform. This limitation lead to a poor understanding of the dynamics inside the reactor as the process is a black box where waste acid is injected and hematite and chloride gas is collected; what happens in-between the two stages is not known to any larger extent. Here Computational Fluid Dynamics (CFD) is a useful tool for the modeling of the physics inside the reactor. In this licentiate thesis, the commercially available CFD software Ansys CFX has been used to model the gas flow and temperature inside the regeneration reactor as part of the main goal of modeling the whole regeneration process. As a first approach, the gas flow and temperature behavior are of certain interest as these quantities determine the dynamics of the injected droplets through their journey inside the reactor, and hence the regeneration process. The present work comprise two papers devoted to the actual application of HCl regeneration, and one paper which emphasize the importance of grid independency studies and the impact of grid element size in regions with high gradients. In the two application-focused papers (Paper A and C) the gas flow and temperature profile inside the reactor is resolved together with the particle (droplet) distribution. In Paper C the study is developed to also comprise the influence on theses quantities due to different locations and spray directions of the spray nozzles located at the top of the reactor.

There is a lack of standardized rules on how the fluid in the turbine should be included in rotor models of hydraulic machinery. This thesis is an attempt to shed some light on this issue. We approach the problem from two viewpoints, situated at place at a hydropower plant and by mathematical analysis.One goal of the thesis is to develop a measurement system that monitors the instantaneous pressure at several locations of a runner blade on a 10 MW Kaplan prototype in Porjus along Lule river. Paper A outlines the development of the measurement system and the instrumentation of the runner blade. Miniature piezo-resisitive pressure transducers were mounted flush to the surface. If instrumentation is successful, the pressure field of the runner blade could be measured simultaneously as the loads and displacements of the guide bearings and the generator.The second objective is concerned with how the motion-induced fluid force affects the dynamic behaviour of the rotor. Inertia and angular momentum of the fluid and shrouding are expected to influence the dynamic behaviour of the turbine. Paper B scrutinizes this assumption by presenting a simple fluid-rotor model that captures the effects of inertia and angular momentum of the fluid on the motion of a confined cylinder. The simplicity of the model allows for powerful analytical solution methods. The results show that fluid inertia, angular momentum and shrouding of hydraulic turbines could have substantial effects on lateral rotor vibrations. This calls for further investigation with a more complex fluid-rotor model that accounts for flexural bending modes.

Lightweight floor structure is widely used in building industries and to have better sound insulation builders come up with different ways of construction. Depending on the construction the floor structure could either be coupled (floor and ceiling coupled by beams) or decoupled (no mechanical connection between floor and ceiling). Although there are many models on coupled structure but for decoupled structure the number is not too many. Keeping that in mind the present thesis talks about lightweight floors: the construction, properties, behaviour etc with a focus on developing a model for decoupled floor structure where the core contribution being the decoupling and adding the moment effect at plate beam joints. The advantage of decoupled structure is that it disconnects the sound bridge through the beams. One consequence on the other hand is that cavity resonance dominates the low frequency region. A comparative analysis is also done with the coupled model. While developing the model this talks about different mathematical tools such as Fourier transform, Floquet principle, Poisson's sum formula etc This also gives an overview of different types of modelling technique available such as analytical, Numerical, energy based approach, empirical method etc. A parametric study is also done here to find out the relative influence of different elements on sound pressure level.

Complete vehicle, system and component target setting for noise, vibration and harshness (NVH) are important activities within automotive product development. New challenges arise when electric motors are introduced into cars traditionally powered by internal combustion engines (ICE). Although the electric powertrain is generally quieter than ICEs, the sound character however is completely different and necessarily not more preferable. The noise signature from an electric traction motor is characterized by speed-dependent high frequency tonal components from the dominating electro-magnetic harmonics, covering a wide rpm-range. With relatively low levels of broad band masking noise from tires and wind, the tonal components can be accented in a large frequency range and contribute to perceived annoyance for the occupants inside the car. Methods for good practice of NVH development work for traditional vehicles have been established and refined during the last decades. With the rapid increase of various types of electric powertrain-equipped low emission vehicles, new methodology is required in order to understand and fulfill expectations on these unaccustomed vehicle-acoustic phenomena. The objective with this thesis was to investigate the audible perception of the electric powertrain and develop and validate methods for assessment of noise transmission. The findings aim to support the complete vehicle, system and component target setting processes to secure a desired sound quality in future electric vehicle launches. The thesis is based upon four papers. The first two papers address the human perception of the sound from the electric powertrain during driving. In Paper 1, the evaluation methodology of electric powertrain sound quality was investigated. It was concluded that the mean ratings of a specific acceleration sound stimulus was judged similarly in two laboratory test environments (listening room and “sound car” respectively) as during on-road driving. Further, with lower level of high frequency (>1 kHz) tonal components, the overall satisfaction and annoyance ratings were improved. The annoyance due to tonal components, stationary as well as speed-dependent, was further studied in Paper 2. The psycho-acoustic metric prominence ratio (PR) was used to quantify the tone levels relative to the adjacent background noise. It was found that for PR-levels below 3 dB, the perceived annoyance was similar independent of frequency range. Increased PR-level provided higher probability of detecting the tones and the perceived annoyance was significantly increased compared to PR<3 dB for tones above 2.5 kHz. The findings from Paper 1 and 2 provide foundation for complete vehicle interior acoustic target specification. The following two papers (Paper 3 and 4) focus on the main mechanical system properties that are responsible for the airborne radiation and transfer of electric powertrain induced noise. Paper 3 has emphasis on the experimental determination of acoustic transfer functions (ATFs) between the car’s interior to multiple positions located on the stator shell surface of an electric rear axle drive. It addresses the ATFs’ spatial resolution with respect to estimated interior noise for theoretically derived and measured surface vibrations. A reciprocal relation was assumed; therefore the measured ATFs could be used to inversely reproduce the sound transmission from the stator shell to the interior. ATFs and surface velocities are also central in Paper 4, where a method for in-situ determination of radiated sound power from a stator shell was presented and validated. By acquiring the operational deflection shape due to an electro-magnetic radial force wave, a simplified expression for the radiation efficiency was estimated. Paper 3 and 4 highlights the advantages of the rotational symmetric force excitation acting on the stator housing which enables sound power as an acoustic source characterization which perhaps is the most adequate measure for system target setting directed towards external suppliers.