Image Credit: Swiss Propulsion Lab, https://ibb.ch/spl_old/news/index.html
Shock diamonds, also known as Mach diamonds, are repeating patterns commonly found in rocket and jet engine exhaust. The exhaust gases continuously over-expand or under-expand relative to ambient pressure. When these mismatches in pressure occur, the flow generates a shock waves that correctively compress or expand the flow. This expansion and compression correction occurs until the jet eventually equalizes with its surrounding pressure downstream. This shock diamond image was generated by firing a 2.5 kilo newton rocket engine at full throttle at the Swiss Propulsion Laboratory.
This image perfectly displays how an extremely chaotic process such as combustion, in contrast can create rhythmic and uniform flow patterns. It is amazing how this incredibly turbulent flow can be visualized as geometric patterns in the exhaust. The quality and lighting of the image perfectly captures the pressure gradients and shock diamonds, without manipulating the flow. Shock diamonds are usually visualized with schlieren imaging or simulations, but here they are made visible directly through the glowing exhaust gases and good photography techniques.
5 Comments. Leave new
Second Prize: Shock diamonds from supersonic flow are so magical. This image shows the shock diamonds so clearly which is a testament to the precision of the engineering. Its impressive to see it captured so clearly.
First Prize. Stationary shock diamonds will always be my favorite fluid flow.
Third Prize: I love the beauty of the photograph is based in technology and the pattern made by the exhaust is very satisfying to look at. It also shows a flow visualization that I did not know of and now want to learn more about.
First Prize: Supersonic flow effects are some of my absolute favorites. Its incredible to see flow phenomena that we can’t easily see in daily life, captured so beautifully. I’ve spent weeks of my life attempting to visualize interactions like this in a supersonic wind tunnel, so to see it so clearly is impressive.
Second Prize: I love shock diamonds. Very few phenomena showcase the complexities – and beauty – of fluid dynamics than jet propulsion. These diamonds are created from pressure differences as the flow exits the nozzle. Luckily, they’re burning at thousands of degrees and lit up for us to see and study.