I recently had the good fortune of visiting some hydrodynamics labs in Sheffield University. Gosh, it was great to see experiments set up covering all aspects of my degree. I got talking to some of the techs and teachers there – super to have technical conversations. IT got me thinking about another conversation in the staff room recently – apparently other people don’t see the world in terms of force diagrams! Like who doesn’t?
This image is of a turbine blade from a steam powered electricity generator. All power stations use steam to turn turbines. This particular blade was hanging and had sensors so that different resonant frequencies could be generated. If you hit the blade gently in different places you get different harmonic tones. If you look at the bottom of the blade you can see where water bubbles have cavitated in the low pressure and then collapsed causing damage. It’s quite incredible to think that happens.
When this was explained to me I didn’t say the only reason I know about cavitation, it felt a touch embarrassing. When in the second year at university I owned a Sega Mega Drive. One of the games I had was 688 Attack Sub. I know that if you tried to travel too fast in the submarine then other subs and vessels could hear you because you caused cavitation around the propellor. Cavitation was a thing to be avoided.