A scramjet (supersonic combustion ramjet) engine is an air-breathing engine designed to operate at very high speeds, typically in the hypersonic regime. The nozzle of a scramjet engine plays a crucial role in accelerating the high-speed air and facilitating efficient combustion. Let’s delve into the definition, explanation, and calculation of the nozzle mass flow rate for a scramjet engine with SI units.
The mass flow rate ṁ through the nozzle of a scramjet engine is the amount of air passing through the nozzle per unit time. Scramjets rely on the high-speed forward motion of the vehicle to compress incoming air and mix it with fuel for combustion.
The velocity () of the incoming air can be related to the Mach number () and the local speed of sound ():
which gives,
where,
- ṁ is the mass flow rate of the nozzle
- is the density of the exhaust gases at the throat
- A is the throat nozzle area
- M is the Mach Number
- a is the speed of sound in the medium