Visualisation of dynamic flow processes using a novel pulsed multi-element hot-wire anemometer.

This thesis describes the development of a novel Single-Element Pulsed Hot-Wire Anemometer (SEPWA) and its multi-element applications to fluid flow visualisation. Unlike previous pulsed anemometers which have separate heating and sensing wires, the methods described here utilise a single wire as both heater and sensor. Therefore it overcomes some of the restrictions which apply to existing PWAs. It is shown that the transient heating and cooling characteristics of such an element is a function of the local convection rate and hence the local fluid velocity. Thus if the heating current is supplied in short duration pulses of constant magnitude, and if the time taken to reach a given set temperature (the Set Temperature Point, STP) is recorded during the heating process, velocity information is acquired as time values rather than the voltages or currents expected from conventional systems. As a single point measurement can be completed in a relatively short time, the system allows access to hundreds of elements per second. As the current is discontinuous, a relatively high value can be used, so giving signal processing advantages over conventional systems. After reviewing the relevant theory and discussing the significance of the system parameters, the concept of active and passive wire time constants are introduced. From these concepts, two operational methods of application of the anemometer are developed and free stream calibration equations are derived. To prove the developed pulsed hot-wire anemometer and the measurement methods, two representative application examples, namely the quantification of flow round a cylinder and the investigation of vortex shedding behind a cylinder are described and results given. The potential for distributed flow visualisation using the SEPWA in association with finite element methods is investigated.

Grantor dc:publisher.institution

Robert Gordon University

Year dc:date.issued

1995

Author dc:creator

• Li, Datian

Advisor dc:contributor.advisor

• K.S. Gow, N.D. Deans and G.M. Maxwell

• Single-element pulsed hot-wire anemometer (SEPWA)
• Fluid flow visualisation
• Set temperature point (STP)
• Velocity information
• Time values
• Free stream calibration equations

Language dc:language

en

Identifier

oai:rgu-repository.worktribe.com:2807449
https://doi.org/10.48526/rgu-wt-2807449

OAI identifier oai:identifier

oai:rgu-repository.worktribe.com:2807449