High Mach Number Flow

High Mach number flow is flow that is faster than the speed of sound (Mach no. greater than 1). This area of fluid dynamics is particularly interesting because of the changes in flow behaviour that occur when the flow becomes supersonic. One of these changes is the appearance of shock waves in which the speed drops and the pressure rises dramatically over a very thin layer of air. The technical challenges increase as the Mach number increases. At hypersonic speeds (Mach no. greater than 5) kinetic heating at the surface of air vehicles becomes significant and at the speeds experienced by re-entry vehicles (Mach no. greater than 30) kinetic heating creates temperatures high enough to melt metal and measures to dissipate the heat must be put in place.

Three types of shock wave (the normal shock, the oblique shock and the conical shock) form the building blocks of supersonic flow. Methods of determining the changes in properties across these shock waves were found by scientists long before the computer era. For the conical shock in particular the solution method is time-consuming, but all three methods can be easily programmed on a computer. On this site you will find free-to-use web applications for the oblique shock and the conical shock as well as some other applications that are useful in the study of supersonic flow. Use web apps.

In the modern era, the digital computer and computational fluid dynamics (CFD) have made it possible to solve the flow over an entire supersonic air vehicle. Atkinson Science has been solving problems in high Mach number flow for many years through its work on aero propulsion systems. Click on the links below to see some examples. Please contact Atkinson Science if you would like to discuss a problem involving high Mach number flow. Contact us.