In a solid propellant rocket engine, the throat exhaust air velocity refers to the speed of the exhaust gases at the throat of the rocket nozzle. Solid propellant rocket engines use a preloaded solid propellant that burns from the inside out, producing hot gases. The throat is the narrowest part of the nozzle, and the velocity at this point is a critical parameter in determining the overall performance of the rocket.
In solid propellant rocket engines, the design of the nozzle is crucial for optimizing thrust and efficiency. Engineers use these relationships to tailor the nozzle geometry for specific performance requirements.
The continuity equation is based on the principle of mass conservation, and Bernoulli’s equation expresses the conservation of energy.
The continuity equation is given by:
where:
-  and  are the cross-sectional areas at the nozzle entrance and exit, respectively,
-  and  are the velocities at the nozzle entrance and exit, respectively.
which gives
where,
- A1Â is the Cross-sectional area at the throat of the nozzle in m2Â
- A2Â is the Cross-sectional area at the exit of the nozzle in m2
- V1Â is the Velocity of the exhaust gases at the throat in m/s
- V2Â is the Velocity of the exhaust gases at the nozzle exit in m/s