Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 63-69). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 63-69). Also available on the Internet.

No description available.

Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Noise generated by fluid power applications can be treated using bladder-style suppressors, and an optimal operating condition for these devices is sought in this thesis. Bladder-style suppressors employ a compliant nitrogen-charged bladder to create an impedance change within the system, reflecting the noise back to the source and preventing it from propagating downstream. The noise in a hydraulic system is created by a pump, the flow source in a hydraulic system, and can be separated into three categories: fluid-borne noise, structure-borne noise and airborne noise. Fluid-borne noise places addition stress on sealing surfaces, potentially causing leaks. Airborne noise can be uncomfortable, even hazardous depending on the level. Bladder-style suppressors primarily treat fluid-borne noise; however, it is seen in the literature that fluid-borne noise is the cause of structure-borne and airborne noise. This thesis presents an optimization method for finding the optimal charge pressure for implementation with a given system operating over a broad range of system pressures. The optimization weights suppressor performance by the spectral content of the fluid-borne noise as well as the duty cycle of the system. A single charge pressure works well over a small range of system pressures, though many fluid power applications operate over a larger range of system pressure than the usable range of a suppressor. For systems operating over an extremely broad pressure range, two suppressors charged to different pressures are used to treat the noise in the entire system pressure range. To determine suppressor performance experimental measurements were performed, and models developed, of the transmission loss of this type of device. A multi-microphone method using transfer function relationships between six sensors determines the transmission loss of the suppressor under test. An equivalent fluid model modeling the wave behavior both upstream and downstream, as well as within the suppressor, was created to predict suppressor transmission loss. Optimal configurations are found for a set of system pressures, charge pressures and duty cycles. Analysis of the results shows the time weighting has a more significant impact on the optimum charge pressure than the frequency weighting, as shown by duty cycles considered in this thesis. In addition, all charge pressures selected as optimal for either single suppressor optimizations or double suppressor optimizations, exhibit the highest transmission loss for a single system pressure in the pressure duty cycle for a simulated machine.

<p>Fluid power education would benefit from the adoption of an alternative to traditional hands-on instructional methods. Hands-on education is invaluable because it offers students experience interacting with and controlling fluid power systems and components, but systems are typically space-consuming and expensive. The study sought to prove the viability of mixed reality (MR) as an alternative to traditional hands-on fluid power instruction through the creation of MR lab exercises. A summary of design methodology was created to demonstrate how virtual fluid power components were modeled and presented in a mixed reality environment. Data was collected from students enrolled at Purdue University who participated in traditional and mixed reality fluid power lab exercises. Student responses were expected to express a positive reception of mixed reality as a fluid power instructional tool. The study anticipated that utilizing mixed reality in a fluid power laboratory setting would increase student comprehension of fluid power concepts. Educational variables were limited by restricting testing to students within the advanced fluid power course of Purdue University’s Polytechnic Institute. Students in this course provided feedback that drew comparisons between traditional and mixed reality instructional methods. Labs were created to remain within the course schedule so as not to disrupt course curriculum. Data from Likert-type surveys were analyzed from pre- and post-lab questionnaires as well as student feedback from their experience after completing each mixed reality (MR) lab. Analysis showed that MR is a viable alternative to traditional hands-on instructional methods as students showed an increase in material comprehension of both fluid power components and concepts. Students perceived MR as a beneficial instructional tool but continued to show preference towards physical interactions with components. A combination of instructional methods is recommended.</p> <p>  </p>

Excessive fluid-borne noise in hydraulic systems is a problem the fluid power industry has long struggled to address. Traditional noise control devices such as Helmholtz resonators, tuning coils, and Herschel-Quincke tubes are generally too large for fluid power systems unless the speed of sound in the device can be reduced. A compliant lining can achieve this effect, but compliance (and lossy compliance) has had little attention in noise control in general, and in fluid power in particular. One means to achieve compliance in these devices, especially at elevated pressures, is through a liner made of syntactic foam, which in this case is a urethane host matrix with embedded hollow, polymer microspheres. The material properties at elevated pressure are unknown by the liner manufacturer, but are known to be pressure- and temperature-dependent. Therefore, the effect of hydrostatic pressures from 2.1-21 MPa and temperatures from 20-45 C on the liner properties, thus the device performance, are studied. For a Helmholtz resonator, a theoretical model is fit to experimentally-measured transmission loss of the device using a least-squares routine, which solves the inverse problem for the complex bulk modulus of the liner. These material properties are used to compare a predictive model of a tuning coil to experimental data, and in a parameter study of a Herschel-Quincke tube. The compliance of the liner is found to lower the effective sound speed by an order of magnitude and decrease the volume of the cavity of a Helmholtz resonator by up to two orders of magnitude. This work is expected to result is more compact noise control devices for fluid power systems.

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Civil Engineering in the Faculty of Engineering at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY 2014 / The current problems of orifice, nozzle and Venturi flow meters are that they are limited to turbulent flow and the permanent pressure drop produced in the pipeline. To improve these inadequacies, converging-diverging (C-D) tubes were manufactured, consisting of symmetrical converging and diverging cones, where the throat is the annular section between the two cones, with various angles and diameter ratios to improve the permanent pressure loss and flow measurement range. The objective of this study was firstly to evaluate the permanent pressure loss, secondly to determine the discharge coefficient values for various C-D tubes and compare them with the existing differential pressure flow meter using Newtonian and non-Newtonian fluids, and finally to assess the performance of these differential pressure flow meters. The tests were conducted on the multipurpose test rig in the slurry laboratory at the Cape Peninsula University of Technology. Newtonian and non-Newtonian fluids were used to conduct experiments in five different C-D tube flow meters with diameter ratios (β) of 0.5, 0.6 and 0.7, and with angles of the wall to the axis of the tube (θ) of 15°, 30° and 45°. The results for each test are presented firstly in the form of static pressure at different flow rates. It was observed that the permanent pressure loss decreases with the flow rate and the length of the C-D tube. Secondly, the results are presented in terms of discharge coefficient versus Reynolds number. It was found that the Cd values at 15° drop earlier than at 30° and 45°; when viscous forces become predominant, the Cd increases with increasing beta ratio. The Cd was found to be independent of the Reynolds number for Re>2000 and also a function of angle and beta ratio. Preamble Performance of a symmetrical converging-diverging tube differential pressure flow meter Finally, the error analyses of discharge coefficients were assessed to determine the performance criteria. The standard variation was found to increase when the Reynolds number decreases. The average discharge coefficient values and their uncertainties were determined to select the most promising C-D tube geometry. An average Cd of 0.96, with an uncertainty of ±0.5 % for a range of Reynolds numbers greater than 2,000 was found. The comparison between C-D tubes 0.6(15-15) and classical Venturi flow meters reveals that C-D 0.6(15-15) performs well in turbulent range and shows only a slight inaccuracy in laminar. This thesis provides a simple geometrical differential pressure flow meter with a constant Cd value over a Reynolds number range of 2000 to 150 000.