Research

My research broadly covers the topics of compressible and multi-phase fluid mechanics. For broader details on these topics, see the How It Works section of the page. To see news about recent publications, look here.

 

Research Projects:

Silencing the Screech Tone - Noise Suppression in Supersonic Jets

 

Time-averaged transverse density gradient looking at the major-axis of a supersonic elliptical jet.
Time-averaged transverse density gradient looking at the major-axis of a supersonic elliptical jet.

Anyone who has ever sat near the wing on a long distance flight is all too familiar with the concept of jet noise - the production of sound by the exhaust of jet engines. If we want to fly faster (and given Australia's Tyranny of Distance, we are surely well-motivated to do so), this noise problem becomes rapidly worse. Once the exhaust of a jet is moving faster than the speed of sound, new noise mechanisms come into play. Amongst these mechanisms is the phenomenon of "screech". A current focus of my research is understanding the mechanism of the screech tone, to develop more efficient ways to suppress it. This will help pave the way for a return to supersonic civilian transport. We conduct this research using a range of specialist experimental tools; see my descriptions of Particle Image Velocimetry (PIV) and schlieren imaging.

This work is undertaken with Prof. Damon Honnery, under the support of an Australian Research Council Discovery Project grant.

 

Supersonic Jet Impingement - A flow of critical importance

Cylinder_Impinging

As noisy as supersonic jets are, the noise problems get worse when the jet strikes against a nearby surface. This is the phenomenon of "supersonic jet impingement", and it has broader applications than you might imagine. These applications range from the very large scale: the exhaust of rockets striking the launch pad during lift-off, to the very small scale, such as the development of needle-free drug delivery devices. We use both experimental (link to PIV page) and numerical techniques to try to understand the highly complex flow physics characterizing these supersonic impinging jets.

 

This work is undertaken with Prof. Julio Soria of Monash University, and Prof. Vassilis Theofilis of the Universidad Politecnica de Madrid, under the support of an Australian Research Council Discovery Project grant.

 

Droplet breakup for fuel and pharmaceutical sprays

BagBreakupMontage

Understanding how droplets of liquid break up in a flow of gas is important for a wide range of fields. Optimizing the injection of fuel into a piston or gas-turbine engine requires the ability to optimize the spray of fuel into the combustion chamber. This in turn requires an understanding of the primary and secondary atomization mechanisms (link). Pharmaceutical particles are typically either produced or delivered through a spray process; thus an understanding of how the drug-containing droplets break up is also critical to optimizing this process. In this research I apply optical diagnostics to study the role of turbulence in droplet breakup processes. This work is closely related to the next topic: engineering pharmaceutical microparticles. The focus in this component is more on the fundamental mechanisms, while the next topic is more about applications.

This work is supported through a Monash University Faculty of Engineering Seed Funding Scheme.

 

Engineering microparticles through controlled atomization in pharmaceutical sprays

pMDI_Schlieren

There are many medical conditions for which simultaneous treatment with multiple therapies is the best course of action. A novel way to maximize the efficiency of this treatment is to combine multiple drugs in a single particle, that is then delivered to the lung. To do this efficiently and safely requires a careful engineering of the particle at a microscopic level, by controlling the spray process that generates the particle. In this research we work with colleagues in Pharmaceutical Science, both industrial and academic, to develop an understanding of spray mechanics that will lead to optimized particle engineering, and thus maximize therapeutic efficacy.

This work is undertaken with Prof. Damon Honnery of Monash & Professer Paul Young of Sydney University, as well as industry partners. It has previously been supported through Australian Research Council Discovery Project grants, and is currently under consideration for Linkage Project funding.

 

Research Students:

I have the great privilege to work with a group of talented, motivated students. In addition to the below-listed PhD students, I also supervise approximately 6-8 final year undergraduate students on projects each year. If they want their photo on the webpage though, they will have to stick around for a PhD!

 

Nick Mason-Smith

Nick

For his PhD program, Nick is conducting research into the fluid mechanics of asthma puffers. Using optical diagnostics, synchrotron measurements and numerical models, he is trying to increase our understanding of the factors that determine drug particle size and distribution in the spray from a medical inhaler.

 

Dominic Tan

Dom

For his PhD, Dominic is studying the production of turbulent mixing noise in supersonic jets. He is developing new techniques to measure fluid density, as well as new approaches to the analysis of velocity data. 

 

 

Joel Weightman

Joel

For his PhD, Joel is studying the physics of supersonic jet impingement. Combining ultra-high-speed schlieren measurements with high-resolution PIV measurements, Joel is hoping to shed new light on the aeroacoustic feedback mechanism that characterizes supersonic jet impingement.

 

Tom KnastIMAG0162

For his PhD, Tom is designing, building and testing a supersonic blowdown tunnel. He will then use this tunnel to study the physics of sonic jets in supersonic crossflow - the mechanism that underlies fuel injection in scramjet engines.

 

 

Graham Bell

DSC_0927Crop

For his PhD, Graham is studying noise mechanisms in high speed jets, with a current focus on the interaction between multiple jet plumes. Graham's work includes the acquisition and analysis of high-resolution Particle Image Velocimetry data, to identify the mechanism by which multiple plumes couple together in their sound production.

 

Marcus Wong

marcus

For his PhD, Marcus is studying the production of broadband shock-associated noise. His project includes the design and commission of a new anechoic co-flow jet facility, as well as the acquisition and analysis of experimental data in that facility.

 

Bhavraj Thethy

OLYMPUS DIGITAL CAMERA

 

For his PhD, Bhav is studying the dynamics of transient shock-driven jets. The application of this work is in the development of pulsed-detonation-combustion engines, designed to offer less emissions and higher fuel efficiency than classical gas turbines. Bhav is co-supervised by Dr. Kilian Oberleithner at the Technical University of Berlin, where he will spend part of his PhD.