AP Composite Propellant Key Physical Properties -...
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MAE 5450 - Propulsion Systems AP Composite Propellant Key Physical Properties • AP chemical formula, NH 4 Cl O 4 13 Fine white powder used as propellant oxidizer Ammonium perchlorate crystals decompose before melting When AP is mixed with a fuel (like a Al powder) or polymeric binder (like HTPB) it can generate considerable het release and allows self-sustained combustion once lit ρ NH 4 ClO 4 = 1.950 g cm 3 M w NH 4 ClO 4 = 117.49 kg / kg − mol
Transcript of AP Composite Propellant Key Physical Properties -...
MAE 5450 - Propulsion Systems
AP Composite Propellant Key Physical Properties
• AP chemical formula, NH4 Cl O4
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Fine white powder usedas propellant oxidizer
Ammonium perchlorate crystals decompose before melting
When AP is mixed with a fuel (like a Al powder) or polymeric binder (like HTPB) it can generate considerable het release and allows self-sustained combustion once lit
ρNH4ClO4= 1.950 g
cm3
MwNH4ClO4= 117.49kg/kg−mol
MAE 5450 - Propulsion Systems
AP Composite Propellant -- Key Physical Properties
• Powdered Elemental Al, micron-scale
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Al Powder acts both as a fuel and combustion catalyst
(molecular weight) kg / kg −molΔH f0
= 0KJ /mol
MAE 5450 - Propulsion Systems
Key Physical Properties, cont’d (2)
• HTPB -- (ARCO R-45TM, polymerization ~ 50)• Full Chemical Formula
• Butadiene C4H6, with n-50 degree of polymerization with hydroxyl termination (hydroxyl makes polymerized rubber more hydrophobic)
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(C4H6)50 OH2 à Molecular Weight ~ 2766 kg/kg-mol
- OH
OH -
MAE 5450 - Propulsion Systems
Key Physical Properties (3)
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ρHTPB = 0.930 gcm3
C4H6( )⋅ OH( )0.40.04
• “Reduced” Chemical Formula w Broken Polymer Bonds
Molecular Weight ~ 54.68 kg/kg-mol
O2 H2 TARs
C4H6 (butadiene gas)
• Main “fuel” for combustion reaction
• Enthalpy of Formation Accounts for Energy Required to Break Polymer Chains
ΔH f0~ 23.99KJ /g−mol = 23.99×10
3KJ /kg−mol
MAE 5450 - Propulsion Systems
Key Physical Properties (4)
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• Insert HTPB PropertiesHere (Not in CEA tables)
• CEA calculates mass properties based on entered chemical formula
• HTPB Properties not listed in CEA tables
MAE 5450 - Propulsion Systems
Key Physical Properties (5)
• Other Important Physical Properties
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Need to calculate your propellant density for“best mixture”
ρHTPB = 0.930 gcm3
ρNH4ClO4= 1.950 g
cm3
ρAl Powder = 2700 kgm3
MAE 5450 - Propulsion Systems
Key Physical Properties (6)
• Other Important Physical Properties
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ρHTPB = 0.930 gcm3
ρNH4ClO4= 1.950 g
cm3
ρAl Powder = 2700 kgm3
MAE 5450 - Propulsion Systems
CEA Input File ….. Example < file >.inp
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problem o/f=1,1.5,2,2.5,3,3.5,4,4.5,5,5.5,6,6.5,7.,7.5,8,9, rocket equilibrium frozen nfz=1 tcest,k=3000 p,bar=30,
react oxid=NH4CLO4(I) wt=100 t,k=298 fuel=AL(cr) wt=25 t,k=298 fuel=HTPB wt=75 t,k=298 h,kj/mol=23.99 C 4 H 6 O 0.04 H 0.04
output plot p t rho m cp gam end
Setup file by default written to < file > input whenCode is saved using > “save as”
