Velocity of Exhaust Gases At The Nozzle For a Liquid Propellant Rocket Engine Calculator

The velocity of the exhaust gases at the nozzle exit for a liquid propellant rocket engine can be expressed using the continuity equation, which is based on the principle of conservation of mass.

The formula essentially states that the product of the cross-sectional area and velocity is constant between the nozzle inlet and exit for an incompressible flow (assuming no losses). As the cross-sectional area decreases, the velocity must increase to maintain mass flow continuity.

The continuity equation is given by:

A1​⋅V1​=A2​⋅V2​

where:

• A1​ and A2​ are the cross-sectional areas at the nozzle entrance and exit, respectively,
• V1​ and V2​ are the velocities at the nozzle entrance and exit, respectively.

which gives

where,

• A₁ is the Cross-sectional area at the throat of the nozzle in m² 
• A₂ is the Cross-sectional area at the exit of the nozzle in m²
• V₁ is the Velocity of the exhaust gases at the throat in m/s
• V₂ is the Velocity of the exhaust gases at the nozzle exit in m/s