a.k.a Doughnut Tails
Have you ever heard of the term “shock diamonds”? These fascinating patterns of light are one of the most intriguing phenomena that can be observed during rocket engine tests. As a person with a strong interest in physics, I couldn’t resist diving deep into the subject of shock diamonds to learn more about this dazzling display of physics in action.
In this blog post, we’ll analyze the what, the how, and the why of shock diamonds. So buckle up!
Shock diamonds are standing wave patterns that are formed in the supersonic exhaust plumes of aerospace propulsion systems, such as supersonic jet engines, rockets, ramjets, or scramjets, and are also referred to as Mach diamonds or Thrust diamonds. As the exhaust plume spreads into the surrounding atmosphere, sudden changes in local density and pressure make the complex flow field known as the “diamonds” apparent. The phenomenon occurs anytime a flow exits a nozzle at supersonic speeds and at a pressure different than that of the external atmosphere it is subjected to.
How are they formed- Shock diamonds are formed due to the interaction of the exhaust plume of the aerospace propulsion systems with the surrounding atmosphere. As the exhaust plume expands into the surrounding atmosphere, its sequence of compression waves propagates upstream into the exhaust plume. These compression waves cause abrupt fluctuations in local density and pressure that are visible as bright spots in the exhaust plume. The bright spots are called shock diamonds as they resemble the facets of a diamond.
Why are they important in aerospace engineering- Shock diamonds are mainly used to infer the performance status of aerospace propulsion systems. The number and size of the shock diamonds are used to gauge their efficiency and the amount of thrust being produced. In addition, shock diamonds can also be used to study the flow field around an aerospace propulsion system and to develop systems with greater efficiency that produces lesser noise, thereby reducing noise pollution.
