Sunday, January 11, 2015

Waterjetting Technology - Dr. Andrej Lichtarowicz

I was saddened, this week, to hear of the passing of Dr. Andrej Lichtarowicz, who died on the the 6th of this month. As Mark Fairhurst noted, Dr. Lichtarowicz, on the faculty at Nottingham University, was a sterling early contributor to the waterjetting community, from its birth back in the early 1970’s. He gave a paper at the first BHRA conference in 1972, and serving as the editor of the 11th Proceedings in 1992.

There were 201 delegates to that first meeting, which was held at the University of Warwick, in Coventry, UK. with 37 papers being given over the course of two and a half days. The use of high pressure waterjet technology was very new at the time, and this was the first time I was able to get together with peer scientists from around the world to discuss what they were doing as well as make a small contribution of our own. But the papers that influenced our lab the most were the two given on cavitation. (One was given by Dr. Andrew Conn and the other by Dr. Lichtarowicz). The reason for this interest was that back in those days the pressures available from high-pressure pumps were restricted to about 30,000 psi, and (without abrasives which only showed up about eight years later) this significantly limited what materials could be cut.

Dr. Conn’s paper related to cavitation at lower pressures and higher volume flow rates, while Dr. Lichtarowicz’ paper covered smaller jet testing at pressures of up to 10,000 psi. Using such a jet he had been able to drill holes in aluminum, which he could not do when the jet was not cavitating. The results were sufficient that we shortly thereafter tried to repeat , and were able to exceed, these results, drilling a hole in a small piece of alumina in less that a minute, although at a pressure of around 18,000 psi.

This led to considerable discussion at the 2nd conference, which was held in Cambridge in 1974, as to whether the results that were being reported were because the jet was breaking up into droplets, or if the result was true cavitation. It was a discussion that Dr. Lichtarowicz, as always, took a significant part in, and although he could not make the third conference (which was in Chicago) by the time of the fourth, in Canterbury in 1978, he was carrying out his research with the nozzle and target submerged with enhanced results from the earlier work.

Over time he developed a small cell, with windows so that the action of the jet could be seen.

Figure 1. Initial design of the Lichtarowicz Cell

The small size of the unit, and the relative simplicity of construction, meant that a number of us, around the world, built such units and used them to help develop a better understanding of what was happening, and how damage could be increased.

One of the early discoveries he made was that, by adjusting the pressure in the chamber, the amount of overall damage (measured by mass loss) could be significantly intensified, and the rate of erosion increased. It was on that basis that we, among others, were able to use cavitating jets to disaggregate rock and coal into fine particles.

Figure 2. View through the port of a Lichtarowicz cell, showing the cavitating jet impacting a metal target.

One of the major uses of the cell was, however, not as a tool to develop faster ways of drilling rock (though it did) but instead to accelerate the rate at which the cavitation resistance of different materials could be determined. Until that time the standard tool for determining cavitation resistance had been the vibrating horn device recommended by ASTM. The problem with this was that it took hours (typically about 24) to generate the data and plot the rate of material removal, because it was so slow. With the cell a similar result could be obtained in minutes. His work led to the development of an ASTM standard first adopted in 1995, and reapproved in 2001 and 2006, with current interest in revision. It went on to be incorporated as part of the International Cavitation Erosion Test.

And so the technology moved forward, Dr. Lichtarowicz gave his last BHR paper at the 12th Conference in Rouen in 1994, and this was a review of some of his earlier work, showing its relevance as industry sought to find cleaner, greener methods for cleaning and material removal. His fundamental work, however, fostered studies that continue to live on, particularly in Japan, where laboratories continue to develop the techniques and ideas that he pioneered over the years. Certainly our own work would not have progressed as far, or in as many directions, without the inspiration of his work, and the many discussions on the technology we held over the years.

He was a good friend, not only to young faculty – as I was when we first met – but to the industry as a whole, and the students that he taught over the years. He was a much respected scientist and colleague and the tools that he developed and helped us learn to use will continue.


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