Published Article / The design, manufacture and use of diaphragm valves in the minerals industry is becoming increasingly important since this sector is restricted from using excessive amounts of water for their operations. This forces a change in the flow properties of these devices from turbulent to laminar in nature and thus necessitates the characterization of these flows for future designs. Furthermore, diaphragm valves have a short service life due to a variety of reasons that includes the abrasive nature of the flow environment. This paper describes the activities of the Adaptronics Advanced Manufacturing Technology Laboratory (AMTL) at the Cape Peninsula University of Technology in the research and development of diaphragm valves using rapid prototyping technologies. As a first step, an experimental diaphragm valve was reverse engineered and retrofitted with ultrasonic transducers used in Ultrasonic Velocity Profiling (UVP) measurements. The use of this device enables measurements of velocity profiles to gain insight into the flow structure within the valve and the increased pressure losses generated within the valve. It also showed that components fabricated using the Z-Corporation machine could withstand the working environment of diaphragm valves. Research is now conducted on ultrasonic transducer placement in the device to further enhance the velocity profiling through the device. As a second step we produced a thin-walled stainless steel diaphragm valve using rapid prototyping technology and investment casting processes. A study of the durability of this device will be conducted and certain geometric and manufacturing aspects of this valve will be discussed.

Thesis (DTech (Electrical Engineering))--Cape Peninsula University of Technology, 2011 / Ultrasonic Velocity Profiling (UVP) is both a method and a device to measure an instantaneous one-dimensional velocity profile along a measurement axis by using Doppler echography. UVP is an ideal technique since it is non-invasive, works with opaque systems, inexpensive, portable and easy to implement relative to other velocity profile measurement methods. Studies have suggested that the accuracy of the measured velocity gradient close to wall interfaces need to be improved. The reason for this is due to, depending on the installation method, distortion caused by cavities situated in front of ultrasonic transducers, measurement volumes overlapping wall interfaces, refraction of the ultrasonic wave as well as sound velocity variations. A new ultrasonic transducer, which incorporates a delay line material optimised for beam forming could reduce these problems (Wiklund, 2007). If these could be addressed, UVP could be used for the measurement of velocity profiles in complex geometries (e.g. contractions, valves, bends and other pipe fittings) where the shape of the velocity profile is critical to derive models for estimating fluid momentum and kinetic energy for energy efficient designs. The objective of this research work was to optimise the UVP system for accurate complex flow measurements by evaluating a specially designed delay line transducer and implementing advanced signal processing techniques. The experimental work was conducted at the Material Science and Technology (MST) group at the Cape Peninsula University of Technology (CPUT). This work also formed part of a collaborative project with SIK - The Swedish Institute for Food and Biotechnology. Acoustic characterisation of the ultrasonic transducers using an advanced robotic setup was done at SI K. Different concentrations of the following non-Newtonian fluids exhibiting different rheological characteristics were used for testing: carboxymethyl cellulose (CMC) solutions, kaolin and bentonite suspensions. Water was used for calibration purposes.