IYPT 2019 Problem 2 Aerosol Demonstration


Hello everyone, I’m back with another video about the IYPT 2019 problems. This week we’re taking a look at IYPT 2019 problem number two “Aerosol” So this video is a bit later that my normal holding schedule says this is my final exam week I know that many of you have asked me to do the soy sauce optics problem Hopefully that will be done during my Christmas break and today let’s talk about aerosol. This Problem filled with water that flows through a small aperture and his problem asks us to investigate the parameters that determine Whether an aerosol is formed rather than a jet and what are some of the properties of this aerosol for this experiment we are using a spray bottle with an adjustable nozzle; a magnifying glass in order to see what is happening near the nozzle and Also some colored LED lights in order to highlight the aerosol as it flies through the air The basic principle of this experiment is really quite simple as we squeeze the handle we push air into the bottle that causes the inside of the bottle to have a higher pressure than the outside of the bottle and Because of this pressure difference water will flow from the inside of the bottle to the nozzle and when it comes out of the nozzle Depending on the opening aperture it will either form a jet when the aperture is quite large and an Aerosol when the aperture is small. This aerosol will have a dispersed cone shape and it will travel forwards as it spreads wider The breakup of the stream of water is mainly caused by the surface instabilities. For a jet at the end of its flow and will break up into small droplets And fall down with a parabolic trajectory when an aerosol is formed it goes over a few distinct stages: at first the stream opens up gradually and forms what’s called an onion stage Then they will transition into a tulip stage And later on transition into a fully developed spring and all of these happens as the liquid pressure increases so we can observe this quite clearly when we Increase the pressure by squeezing down on the handle the stream will begin as a sheet with some sort of surface wave on it Then the sheet will start to detach on myself and in form a solid cylinder With the same surface wave and then later on the cylinder breaks up into smaller droplets. And this is how the aerosol is formed We can change the jet velocity By changing the aperture diameter and also the pressure that we apply on to the fluid When the jet velocity is low We see a tripling flow and then later on as we increase the jet velocity we can see a laminar flow region then a turbulent flow region and Beyond that we see a fully developed spray region as seen in this graph the sources for these graphs will be linked in the description below Make sure to give this video a thumbs up and then also to subscribe to our channel if you haven’t And I’ll show you some more clips of my aerosol. I’ll see you in my next video. Bye