# Examples¶

The following examples demonstrate the use of RocketProps.

## Propellant Tank Volume¶

There is a function within RocketProps to calculate the required volume of a propellant tank.

Use rocketprops.tank_supt.calc_tank_volume as in the code below.

from rocketprops.tank_supt import calc_tank_volume
from rocketprops.rocket_prop import get_prop
"""
Calculate the required volume of a Hydrazine (N2H4) tank.
Assume:
required usable propellant is 50 kg
vehicle max operating/storage/transport temperature is 50 deg C.
minimum ullage volume is 3%.
expulsion efficiency = 98%.
"""
pObj = get_prop('N2H4')

cc_Total, kg_loaded, kg_residual = calc_tank_volume( pObj, kg_expelled=50.0,
TmaxC=50.0, expPcent=98.0, ullPcent=3.0 )
print('cc_Total    = %g cc'%cc_Total)
print('residual propellant mass =  %g kg'%kg_residual )


Output from the above script is:

cc_Total    = 53510.4 cc
loaded   propellant mass = 51.0526 kg
residual propellant mass =  1.05263 kg


## Propellant Line¶

Propellant line calculations are supported by rocketprops.line_supt.

Given a desired flow rate of propellant, calculate the diameter and pressure drop in a propellant line.

Can input mass flow rate and line velocity, or mass flow rate and inside diameter.

from rocketprops.line_supt import calc_line_id_dp, calc_line_vel_dp
from rocketprops.rocket_prop import get_prop

pObj = get_prop('hydrazine')

ID, deltaP = calc_line_id_dp( pObj, TdegR=530.0, Ppsia=240.0,
wdotPPS=0.5, velFPS=13,
roughness=5.0E-6,  Kfactors=5.0, len_inches=50.0)
print( 'Inside Diam=%g inches, Pressure Drop =%g psid'%(ID, deltaP) )

vel, dp = calc_line_vel_dp( pObj, TdegR=530.0, Ppsia=240.0,
wdotPPS=0.5, IDinches=ID,
roughness=5.0E-6,  Kfactors=5.0, len_inches=50.0)
print( 'Velocity = %g ft/sec, Pressure Drop =%g psid'%(vel, deltaP) )


Output from the above script is:

Inside Diam=0.334523 inches, Pressure Drop =9.66264 psid
Velocity = 13 ft/sec, Pressure Drop =9.66264 psid


## Valve¶

Valve pressure drops can be calculated using rocketprops.valve_supt.

The script below compares valve pressure drops using both the imperial valve flow coefficient (Cv), and the metric flow coefficient (Kv).

from rocketprops.rocket_prop import get_prop
from rocketprops.valve_supt import cv_valve_dp, kv_valve_dp

"""
Calculate the pressure drop across an MMH valve with given mass flow rate
"""
pObj = get_prop( 'MMH' )

# Imperial valve flow coefficient, Cv
dp = cv_valve_dp( pObj, Cv=1.0, wdotPPS=0.5, TdegR=530.0, Ppsia=1000.0)
print('Cv = 1.0           deltaP = %g psid'%dp)

# Metric valve flow coefficient, Kv
Kv = 1.0 / 1.1560992283526375  # Conversion factor for Cv to Kv
dp = kv_valve_dp( pObj, Kv=Kv, wdotPPS=0.5, TdegR=530.0, Ppsia=1000.0)
print('Kv = 1.0/convFact  deltaP = %g psid'%dp)


Output from the above script is:

Cv = 1.0           deltaP = 14.6749 psid
Kv = 1.0/convFact  deltaP = 14.6749 psid


## Injector Orifice¶

Some injector orifice calculations are supported with rocketprops.injector_supt.

The script below calculates the injection velocity and mass flow rate for a sample N2O4 injector.

from rocketprops.rocket_prop import get_prop
from rocketprops.injector_supt import calc_inj_velocity, calc_orifice_flow_rate

"""
Calculate the injection velocity of an injector orifice and its mass flow rate
"""
pObj = get_prop( 'N2O4' )
ft_per_sec = calc_inj_velocity( pObj, dPpsia=50.0, TdegR=530.0, Ppsia=1000.0)
print( 'velocity =',ft_per_sec, 'ft/s' )

wdot = calc_orifice_flow_rate(pObj, CdOrf=0.75, DiamInches=0.01,
dPpsia=50.0, TdegR=530.0, Ppsia=1000.0)
print( 'Orifice flow rate =',wdot , 'lbm/sec' )


Output from the above script is:

velocity = 71.7716993053127 ft/s
Orifice flow rate = 0.00264060215451235 lbm/sec