An investigation of the dynamic lift on the central tube in square tube arrays is conducted. Three array spacing ratios with P/ D = 3.37, 2.18 and 1.58, corresponding to large, intermediate and small spacing ratios are investigated. These three classes exhibit specific flow characteristics and distinct behavior during acoustic resonance. The aim of the present investigation is to determine the effect of the acoustic pressure field and its contribution to dynamic lift during acoustic resonance. During acoustic resonance there are two sources of dynamic lift. One source is provided by the sound field. The standing wave excited during resonance causes dynamic lift from the acoustic pressure distribution on the surface of the cylinder. In the absence of flow, loud speakers are used to excite the first transverse acoustic mode over a range of sound pressure levels, effectively determining the relationship between the resultant dynamic lift and sound pressure level of the acoustic standing wave. The dynamic lift due to the sound field is well predicted by numerical simulation of the acoustic pressure distribution in the tube array. Using the validated numerical simulation it is possible to extend the results to a large range of cylinder diameter to wavelength ratios. The other source of dynamic lift is provided by the periodic flow though the tube array, known as vortex shedding, which is enhanced during resonance. The total dynamic lift is dependant on the phase shift between the sound field and aerodynamic lift components. For small and intermediate tube arrays, acoustic resonance occurs before coincidence of the natural vortex shedding frequency and the acoustic mode. For the large tube array, frequency coincidence occurs within the resonance range. The phase shift between the dynamic lift due to sound and that due to the aerodynamic lift is small for the pre-coincidence resonance range observed for small and intermediate tube arrays and therefore the total dynamic lift is well predicted by the sum of the magnitudes of the dynamic lift due to the sound field and aerodynamic lift components caused by vortex shedding. Past the frequency of coincidence, a phase jump occurs in the aerodynamic lift causing a large phase shift between the sound field and aerodynamic lift components in the large spacing ratio array. The summation of the aerodynamic lift and the lift due to the sound field over predicts the total dynamic lift measured during acoustic resonance in this case. The present results are used to develop a conservative guideline for estimating the total dynamic lift during acoustic resonance. / Thesis / Master of Applied Science (MASc)

Shaft mounted speed reducers are used in material handling applications, such as conveyor systems for transporting ore out of mine shafts. A subbase joins the reducer with an electric motor, and serves to limit the misalignment between the motor shaft and the reducer input shaft. The entire assembly is supported at two points: the axis of rotation of the reducer output shaft, which is fixed, and a clevis-pin joint under the motor, which prevents rotation of the assembly about the reducer output shaft axis. In an effort to reduce the production and material costs of subbases that support shaft mounted reducers, Rexnord Corp. is implementing subbase designs that are lighter weight and easier to manufacture than current designs. Impeding the implementation of lower cost designs is the lack of an equation to properly choose subbase dimensions for acceptable values of shaft misalignment. Trial and error in subbase construction may provide designs that give acceptable results for misalignment. Given an equation, however, the weight could be minimized while still limiting misalignment at the coupling location. The project goal is to provide equations that give shaft misalignment as a function of three subbase parameters: tube thickness, mounting strap width, and end cap thickness. Developing design equations by analytical methods is investigated first. Next, finite element models are used to check the analytical results for accuracy. Finally, finite element models are used to perform design sensitivity studies where needed. The final equations for misalignment are given as functions of the three design variables. / Master of Science

The study of fluidelastic instability in tube arrays has been ongoing for four decades. Although much research has been conducted, a full understanding of the mechanisms involved is still not available. Designers of cross-flow heat exchangers must depend on experience and empirical data from laboratory studies. As new designs are developed, which differ from these experimental facilities, there is an increased risk of failure due to fluidelastic instability. An experimental program was conducted to examine fluidelastic instability in inline and rotated square finned tube arrays. Three arrays of each geometry type were studied; two with serrated, helically wound finned tubes of different fin densities, and the third, a bare tube which had the same base diameter as the finned tubes. The tube pitch was kept constant to reduce the number of test sections required under this investigation. As a result, the bare tube array has a larger tube pitch ratio than that of previous researchers. The finned tubes under consideration were commercial fmned tubes of a type typically used in the fossil and process industries. The addition of fins to tubes in heat exchangers enhances heat transfer due to the increased surface area and the turbulence produced by the flow moving over the fins. The resulting flow pattern/distribution due to the fins is therefore much more complicated than in bare tube arrays. Previous research has shown that an effective diameter of a finned tube is useful in the prediction of vortex shedding. This concept is used to compare the finned tube results with the existing bare tube array guidelines for fluidelastic instability. All of the tube arrays in the present study have the same tube pitch, and have been scaled to have the same mass ratio. Results for the rotated square arrays show that the use of an effective diameter is beneficial in the scaling of fluidelastic instability and the finned tube results are found to fit within the scatter of the existing data for fluidelastic instability. For in-line square arrays, the results indicate that fins significantly increase the stability threshold. / Thesis / Master of Applied Science (MASc)

Controlled deformation. Under with conditions can the iron deformation process be affected? This work is focused on expanding steel profiles. Using various tests, I will confront the visual results with the technical possibilities of the material. Attempting to find a boundary that is still permissible in terms of maximum steel loading just before the material starts to fail. The resulting installation should show the enormous forces needed to distort the material, where the viewer will be directly confront with the process.

The thesis describes the knowledge from a round tube bending technology, as a description of conventional and unconventional devices. There are technological parameters in relation to the creation of defects, and equations for determining the bending moment. These knowledge has been generalized and applied to solution the changes of cross-section shape and thickness in the bending of square cross-section. The solution was implemented to specific component (20x2 mm steel tube with two successive radii R57,2 and R131,5). The results of experiments shows that the material is almost rigid-perfectly plastic, in the most stressed areas has a sufficient supply of material formability. Thickness measurement was applied to calculate the approximate center of gravity changes. This shows a shift of 1.4 mm, which is negligible value for the pure bending. The end of the thesis summarizes the deficiencies of current manufacturing technology, which used mandrel is inadequate, wrong located and poor lubrication.