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Characteristic Velocity

 

Characteristic Velocity Formula

U=pcA˙mf     (Characteristic Velocity)

pc=U˙mfA 

A=U˙mfpc 

˙mf=pcAU 

Symbol English Metric
U = Characteristic Velocity ft/sec m/s
pc = Chamber Pressure lbf/in2 Pa
A  (Greek symbol rho) = Throat Area ft2 m2
˙mf = Mass Flow Rate lbm/sec kg/s

Characteristic velocity, abbreviated as U, measure the effectiveness of the combustion of a rocket engine at high temperature and pressure, seperate from nozzle performance.  It is used to compare different propellant and propulsion systems.  Characteristic velocity is used in the field of rocketry and aerospace engineering and refers to a specific velocity that is characteristic of a particular propulsion system or rocket engine.

In rocketry, the characteristic velocity is a measure of the performance of a rocket engine.  It represents the average exhaust velocity of the propellant expelled from the engine.  The exhaust velocity is the speed at which the propellant gases exit the rocket nozzle relative to the rocket itself.  It is an important parameter in rocketry as it helps determine the rocket's performance, such as its maximum achievable velocity and its ability to overcome the force of gravity and reach orbit or escape Earth's atmosphere.

It's worth noting that the characteristic velocity is not an actual velocity that the rocket achieves, but rather a figure of merit used in rocket engine design and analysis.  It provides a convenient way to compare the performance of different rocket engines or propulsion systems.

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Characteristic Velocity Formula

U=2EccΔT     (Characteristic Velocity)

Ec=U22cΔT

c=U22EcΔT

ΔT=U22Ecc

Symbol English Metric
U = Characteristic Velocity ft/sec m/s
Ec = Eckert Number dimensionless dimensionless
c = Specific Heat btu/lbmF kJ/kgK  
ΔT = Temperature Change  F K 

 

 

 

 

 

 

 

 

 

 

 

 

Characteristic Velocity Formula

U=ΔpEuρ     (Characteristic Velocity)

Δp=U2Euρ

Eu=ΔpρU2

ρ=ΔpEuU2

Symbol English Metric
U = Characteristic Velocity ft/sec m/s
Δp = Pressure Differential lbf/in2 Pa
Eu = Euler Number dimensionless dimensionless
ρ  (Greek symbol rho) = Density lbm/ft3 kg/m3