The blog Fuck Yeah Fluid Dynamics posted some stills from this video recently. The images were fantastic, but I didn't totally understand what I was seeing. Thankfully, FYFD blogger (and aerospace engineering Ph.D. student) Nicole Sharp was kind enough to answer my questions.
What you're looking at is a rocket engine. The video shows what happens to airflow in the engine as it goes from subsonic to supersonic. In the video and the pictures, you can see a dark red line moving down the tunnel. That's the edge of the shockwave that marks the boundary between subsonic air and Mach 1. You should also pay attention to the little black vortices that whirl away from the edge of the engine wall. Those are pretty important.
The whole goal of an experiment like this, Sharp told me, is to learn more about shockwave/boundary layer interactions. The boundary layer is a very small region, right against the walls of the engine. It's the point where friction and viscosity matter to the air flow.
"Say I've got an airplane wing and air moving over it at 800 mph," Sharp said. "If I am a meter away from that wing the air doesn't care. It's not impacted by flow. But right at the surface of the wing you have friction, so the air can't just slide along surface. This is the region where the velocity of air changes from 0 to 800 miles per hour. It's millimeters or centimeters, but it's where you have a huge change in velocity."
It's important to study what happens in that boundary layer because this is where turbulence happens. In fact, those vortices you see are turbulence, generated when the impact of the shockwave hits the engine wall. That turbulence can cause pressure fluctuations, Sharp said. And those pressure fluctuations can have real, physical impacts on the structural integrity of the engine.
A scrap dealer cleaning out a deceased engineer’s basement in Pittsburg, Pennsylvania found two massive 1960s computers, magnetic tape data storage systems, and hundreds of tape reels, all of which was marked as the property of NASA. The scrap dealer called NASA to report what he found and the agency’s Office of the Inspector General […]
The Department of Agriculture’s chief scientist oversees more than 1,000 scientists in 100 research facilities: Trump’s pick to run the agency is Sam Clovis, a climate-denying talk-radio host who not only lacks any kind of scientific degrees — he didn’t take a single science course at university.
NASA’s Langley Research Center in Hampton, Virginia turns 100 this year. In celebration, the space agency produced this short documentary and enlisted Captain Kirk himself, William Shatner, to narrate. Here are just a few highlights from NASA Langley’s incredible history: • In times of peace and war, NASA Langley helped to create a better airplane, […]
Just because English has become the common global tongue doesn’t mean it’s the easiest language to write—even for native speakers. If you’re looking to improve your written communication skills, especially on your smartphone, take a look at Ginger Page.Ginger is a cross-platform app that offers corrections for phrasing as well as grammar. It’s powered by […]
The current web development landscape is rife with buzzwords and technology that gets abandoned almost as soon as it’s made. If you’ve never written a line of code before, it can be hard to figure out what’s coming, what’s here to stay, or how to get ahead.This Beginner Web Development Bundle is a great place […]
The Fader Stealth Quadcopter from TRNDlabs packs incredible flight performance into a package small enough to land on your phone screen, and it’s available now in the Boing Boing Store.The Fader’s six-axis gyroscope module gives it perfect balance in the air. This makes the onboard 720p HD camera all the better for shooting amazing flight […]