100 lbf Engine | |
| RocketIsp version 0.1.12 | Sunday, Jul 19, 2026 at 09:21AM |
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N2O4/N2H4 IspVac = 317.666 sec MRcore = 1.26 MRthruster = 1.071 Rt = 0.360233 in At = 0.407677 in**2 Pc = 137 psia Fvac = 100 lbf cham_freq = 17965.2 Hz(82% 1T) Nelements = 596 (set by acoustics) elemDens = 75.8851 elem/in**2 DorfOx = 0.0097 in DorfFuel = 0.0095 in |
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| Geometry |
|---|
| Input | |||
|---|---|---|---|
| Parameter = | Value | Alt Value | Description |
| cham_conv_deg = | 30.00 deg | half angle of conical convergent section | |
| CR = | 2.5 | chamber contraction ratio (Ainj / Athroat) | |
| eps = | 75 | nozzle area ratio (Aexit / Athroat) | |
| LchamberInp = | None in | user input value of chamber length (will override all other entries) | |
| LchmMin = | 1.000 in |
2.540 cm 0.083 ft |
minimum chamber length (will override LchmOvrDt) |
| LchmOvrDt = | 3 | ratio of chamber length to throat diameter (Lcham / Dthrt) | |
| LnozInp = | None in | user input nozzle length (will override pcentBell) | |
| pcentBell = | 80 | nozzle percent bell (Lnoz / L_15deg_cone) | |
| RchmConv = | 1 | radius of curvature at start of convergent section (Rconv / Rthrt) | |
| RdwnThroat = | 1 | radius of curvature just downstream of throat (Rdownstream / Rthrt) | |
| Rthrt = | 0.360 in |
0.915 cm 0.030 ft |
throat radius |
| RupThroat = | 1.5 | radius of curvature just upstream of throat (Rupstream / Rthrt) | |
| Output | |||
|---|---|---|---|
| Parameter = | Value | Alt Value | Description |
| Ainj = | 1.019 in**2 | 6.575 cm**2 | area of injector |
| At = | 0.408 in**2 | 2.630 cm**2 | throat area |
| Dexit = | 6.239 in |
15.848 cm 0.520 ft |
nozzle exit diameter |
| Dinj = | 1.139 in |
2.893 cm 0.095 ft |
diameter of injector |
| Dthrt = | 0.720 in |
1.830 cm 0.060 ft |
throat diameter |
| entrance_angle = | 35.70 deg | nozzle initial expansion angle | |
| exit_angle = | 7.63 deg | nozzle exit angle | |
| Lcham_conv = | 0.604 in |
1.534 cm 0.050 ft |
length of convergent section of chamber |
| Lcham_cyl = | 1.557 in |
3.956 cm 0.130 ft |
length of cylindrical section of chamber |
| Lnoz = | 8.239 in |
20.927 cm 0.687 ft |
nozzle length |
| Ltotal = | 10.400 in |
26.416 cm 0.867 ft |
nozzle + chamber length |
| Rinj = | 0.570 in |
1.447 cm 0.047 ft |
radius of injector |
| Vcham = | 2.0 in**3 | 32.8 cm**3 | approximate chamber volume |
| N2O4/N2H4 Core Stream Tube |
|---|
| Input | |||
|---|---|---|---|
| Parameter = | Value | Alt Value | Description |
| adjCstarODE = | 1 | multiplier on NASA CEA code value of cstar ODE (default is 1.0) | |
| adjIspIdeal = | 1 | multiplier on NASA CEA code value of Isp ODE (default is 1.0) | |
| CdThroat = | 0.985313 |
Cd of throat (RocketThruster object may override) (MLP fit) |
|
| fuelName = | N2H4 | name of fuel (e.g. MMH, LH2) | |
| ignore_noz_sep = | 0 | flag to force nozzle flow separation to be ignored (USE WITH CAUTION) | |
| MRcore = | 1.26 | mixture ratio of core flow (ox flow rate / fuel flow rate) | |
| oxName = | N2O4 | name of oxidizer (e.g. N2O4, LOX) | |
| Pamb = | 0.00 psia |
0.00 MPa 0.00 atm 0.00 bar |
ambient pressure (for example sea level is 14.7 psia) |
| Pc = | 137.0 psia |
0.94 MPa 9.32 atm 9.45 bar |
chamber pressure |
| Output | |||
|---|---|---|---|
| Parameter = | Value | Alt Value | Description |
| CfAmbDel = | 1.79046 | delivered ambient thrust coefficient | |
| CfVacDel = | 1.79046 | delivered vacuum thrust coefficient | |
| CfVacIdeal = | 1.938 | ideal vacuum thrust coefficient | |
| cstarERE = | 5641.5 ft/s | 1719.5 m/s | delivered core cstar |
| cstarODE = | 5787.6 ft/s | 1764.1 m/s | core ideal cstar |
| FvacBarrier = | 29.6 lbf | 131.8 N | vacuum thrust due to barrier stream tube |
| FvacCore = | 70.4 lbf | 313.1 N | vacuum thrust due to core stream tube |
| FvacTotal = | 100.0 lbf | 444.8 N | total vacuum thrust |
| gammaChm = | 1.13912 | core gas ratio of specific heats (Cp/Cv) | |
| IspDel = | 317.67 sec |
3115.24 N-sec/kg 3.12 km/sec |
<=== thruster delivered vacuum Isp ===> |
| IspDel_core = | 320.52 sec |
3143.23 N-sec/kg 3.14 km/sec |
delivered Isp of core stream tube |
| IspODE = | 348.61 sec |
3418.74 N-sec/kg 3.42 km/sec |
core one dimensional equilibrium Isp |
| IspODF = | 327.19 sec |
3208.59 N-sec/kg 3.21 km/sec |
core frozen Isp |
| IspODK = | 335.20 sec |
3287.20 N-sec/kg 3.29 km/sec |
core one dimensional kinetic Isp |
| MRthruster = | 1.071 | total thruster mixture ratio') | |
| MWchm = | 20.222 g/gmole | core gas molecular weight | |
| Pexit = | 0.1116 psia |
0.00 MPa 0.01 atm 0.01 bar |
nozzle exit pressure |
| TcODE = | 5521.3 degR |
3067.4 degK 2794.2 degC 5061.6 degF |
ideal core gas temperature |
| wdotFl = | 0.152 lbm/s | 0.069 kg/s | total fuel flow rate |
| wdotOx = | 0.163 lbm/s | 0.074 kg/s | total oxidizer flow rate |
| wdotTot = | 0.315 lbm/s | 0.143 kg/s | total propellant flow rate (ox+fuel) |
| At Injector Face | |||
| Parameter = | Value | Alt Value | Description |
| wdotFl_cInit = | 0.129 lbm/s | 0.059 kg/s | initial core fuel flow rate (before any entrainment) |
| wdotFlFFC = | 0.023 lbm/s | 0.010 kg/s | fuel film coolant flow rate injected at perimeter |
| wdotTot_cInit = | 0.292 lbm/s | 0.132 kg/s | initial core total flow rate (before any entrainment) |
| After Entrainment | |||
| Parameter = | Value | Alt Value | Description |
| wdotFl_b = | 0.055 lbm/s | 0.025 kg/s | barrier fuel flow rate (FFC + entrained) |
| wdotFl_c = | 0.097 lbm/s | 0.044 kg/s | final core fuel flow rate (injected - entrained) |
| wdotOx_b = | 0.040 lbm/s | 0.018 kg/s | barrier oxidizer flow rate (all entrained) |
| wdotOx_c = | 0.122 lbm/s | 0.056 kg/s | final core oxidizer flow rate (injected - entrained) |
| wdotTot_b = | 0.095 lbm/s | 0.043 kg/s | total barrier propellant flow rate (includes entrained) |
| wdotTot_c = | 0.220 lbm/s | 0.100 kg/s | total final core propellant flow rate (injected - entrained) |
| Efficiencies |
|---|
| Output | ||
|---|---|---|
| Parameter = | Value | Description |
| Isp = | 0.91122 | Overall Isp Efficiency |
| Noz = | 0.94322 | Nozzle Efficiency |
| ERE = | 0.97476 | Energy Release Efficiency of Chamber |
| FFC = | 0.99109 | (barrier calc) Fuel Film Cooling Efficiency of Chamber |
| Nozzle | ||
| Parameter = | Value | Description |
| Div = | 0.99334 | (simple fit eps=75, %bell=80) Divergence Efficiency of Nozzle |
| Kin = | 0.96153 | (MLP fit) Kinetic Efficiency of Nozzle |
| BL = | 0.98753 | (MLP fit) Boundary Layer Efficiency of Nozzle |
| Chamber | ||
| Parameter = | Value | Description |
| Mix = | 0.99823 | (mixAngle=0.84 deg) Inter-Element Mixing Efficiency of Injector |
| Em = | 0.98478 | (Rupe elemEm=0.8) Intra-Element Mixing Efficiency of Injector |
| Vap = | 0.99159 | (gen vaporized length) Vaporization Efficiency of Injector |
| Ignored Efficiencies |
|---|
| TP: Two Phase Efficiency of Nozzle |
| HL: Heat Loss Efficiency of Chamber |
| Barrier Stream Tube |
|---|
| Input | ||
|---|---|---|
| Parameter = | Value | Description |
| ko = | 0.035 | entrainment constant (typical value is 0.035, range from 0.03 to 0.06) |
| pcentFFC = | 15 | percent fuel film cooling ( FFC flowrate / total fuel flowrate) |
| Output | |||
|---|---|---|---|
| Parameter = | Value | Alt Value | Description |
| cstarERE_b = | 5585.3 ft/s | 1702.4 m/s | delivered cstar |
| cstarODE_b = | 5729.9 ft/s | 1746.5 m/s | ideal equilibrium cstar |
| fracEntr = | 0.247991 | fraction of core flow entrained into barrier | |
| fracKin_b = | 0.310422 | fraction of kinetic completion in barrier | |
| IspDel_b = | 311.08 sec |
3050.67 N-sec/kg 3.05 km/sec |
delivered vacuum barrier Isp |
| IspODE_b = | 327.914 | sec. ideal equilibrium barrier Isp | |
| IspODF_b = | 324.17 sec |
3179.00 N-sec/kg 3.18 km/sec |
ideal frozen barrier Isp |
| IspODK_b = | 325.33 sec |
3190.40 N-sec/kg 3.19 km/sec |
vacuum kinetic Isp of barrier |
| MRbarrier = | 0.736153 | barrier mixture ratio at throat | |
| MRwall = | 0.40842 | mixture ratio at throat wall | |
| TcODE_b = | 4769.4 degR |
2649.7 degK 2376.5 degC 4309.8 degF |
average ideal ODE temperature of barrier gas |
| Twallgas = | 3654.9 degR |
2030.5 degK 1757.4 degC 3195.3 degF |
temperature of gas at throat wall (cooler upstream) |
| WentrOvWcool = | 3.17594 | ratio of entrained flow rate to FFC flow rate | |
| N2O4/N2H4 Injector |
|---|
| Assumptions |
|---|
| NOTE: Injector elements are designed by Initial Core Flow ONLY. |
| Fuel Film Cooling orifices must be designed separately. |
| NOTE: number of elements set by acoustics |
| Acoustic frequency set by 3T |
| Fuel Orifice Diameter Meets Stability Requirement of >= 9.5 mil |
| Chamber design frequency set by: acoustics to: 17965 Hz,(82% 1T) |
| Input | |||
|---|---|---|---|
| Parameter = | Value | Alt Value | Description |
| desAcousMode = | 3T | driving acoustic mode of injector OR acoustic mode multiplier (setNelementsBy=="acoustics" and setAcousticFreqBy=="mode") | |
| DorfMin = | 0.0080 in |
8.000 mil 0.203 mm |
minimum orifice diameter (lower limit) |
| elemEm = | 0.8 | intra-element Rupe mixing factor (0.7 below ave, 0.8 ave, 0.9 above ave) | |
| setAcousticFreqBy = | mode | flag indicating how to determine design frequency. (can be "mode" or "freq") | |
| setNelementsBy = | acoustics | flag determines how to calculate number of elements ( "acoustics", "elem_density", "input") | |
| Ox Properties | |||
| Parameter = | Value | Alt Value | Description |
| CdOxOrf = | 0.75 | flow coefficient of oxidizer orifices | |
| dropCorrOx = | 0.33 | oxidizer drop size multiplier (showerhead=3.0, like-doublet=1.0, vortex=0.5, unlike-doublet=0.33) | |
| fdPinjOx = | 0.25 | fraction of Pc used as oxidizer injector pressure drop | |
| LfanOvDorfOx = | 20 | fan length / oxidizer orifice diameter | |
| OxOrfPerEl = | 1 | number of oxidizer orifices per element | |
| Tox = | 530.0 degR |
294.4 degK 21.3 degC 70.3 degF |
temperature of oxidizer |
| Fuel Properties | |||
| Parameter = | Value | Alt Value | Description |
| CdFuelOrf = | 0.75 | flow coefficient of fuel orifices | |
| dropCorrFuel = | 0.33 | fuel drop size multiplier (showerhead=3.0, like-doublet=1.0, vortex=0.5, unlike-doublet=0.33) | |
| fdPinjFuel = | 0.25 | fraction of Pc used as fuel injector pressure drop | |
| FuelOrfPerEl = | 1 | number of fuel orifices per element | |
| LfanOvDorfFuel = | 20 | fan length / fuel orifice diameter | |
| lolFuelElem = | 0 | flag for like-on-like fuel element (determines strouhal multiplier) | |
| Tfuel = | 530.0 degR |
294.4 degK 21.3 degC 70.3 degF |
temperature of fuel |
| Output | |||
|---|---|---|---|
| Parameter = | Value | Alt Value | Description |
| des_freq = | 17965.2 Hz | chamber design acoustic frequency | |
| DorfFlForHzLimit = | 0.009 in |
9.484 mil 0.241 mm |
fuel orifice Diameter for frequency in Hewitt Correlation |
| elemDensCalc = | 75.885 elem/in**2 | 11.762 elem/cm**2 | element density on injector face |
| Nelements = | 596 | number of elements on injector face | |
| NelemMakable = | 837 | maximum number of makable elements giving correct flow rate (diam=DorfMin) | |
| Ox Properties | |||
| Parameter = | Value | Alt Value | Description |
| AfloOx = | 0.044 in**2 | 0.286 cm**2 | total flow area of oxidizer |
| dHvapOx = | 177.52 BTU/lbm |
98.69 cal/g 412.91 J/g |
oxidizer heat of vaporization |
| DorfOx = | 0.0097 in |
9.740 mil 0.247 mm |
oxidizer orifice diameter |
| dpOx = | 34.25 psid |
0.24 MPa 2.33 atm 2.36 bar |
oxidizer injector pressure drop |
| MolWtOx = | 92.011 g/gmole | oxidizer molecular weight | |
| NOxOrf = | 596 | number of oxidizer orifices on injector face | |
| sgOx = | 1.439 g/ml |
0.052 lbm/inch**3 89.825 lbm/ft**3 |
oxidizer density |
| surfOx = | 1.483e-04 lbf/in |
2.598e-02 N/m 2.598e+01 mN/m 2.598e+01 dyne/cm |
oxidizer surface tension |
| velOx_fps = | 59.4 ft/s | 18.1 m/s | velocity of injected oxidizer |
| viscOx = | 2.777e-04 poise |
2.777e-02 cpoise 2.777e-05 Pa*s 6.718e-02 lbm/hr/ft |
oxidizer viscosity |
| Fuel Properties | |||
| Parameter = | Value | Alt Value | Description |
| AfloFuel = | 0.042 in**2 | 0.271 cm**2 | total flow area of fuel |
| dHvapFuel = | 582.19 BTU/lbm |
323.66 cal/g 1354.18 J/g |
fuel heat of vaporization |
| DorfFuel = | 0.0095 in |
9.482 mil 0.241 mm |
fuel orifice diameter |
| dpFuel = | 34.25 psid |
0.24 MPa 2.33 atm 2.36 bar |
fuel injector pressure drop |
| MolWtFuel = | 32.045 g/gmole | fuel molecular weight | |
| NFuelOrf = | 596 | number of fuel orifices on injector face | |
| sgFuel = | 1.009 g/ml |
0.036 lbm/inch**3 63.003 lbm/ft**3 |
fuel density |
| surfFuel = | 3.846e-04 lbf/in |
6.736e-02 N/m 6.736e+01 mN/m 6.736e+01 dyne/cm |
fuel surface tension |
| velFuel_fps = | 71.0 ft/s | 21.6 m/s | velocity of injected fuel |
| viscFuel = | 6.764e-04 poise |
6.764e-02 cpoise 6.764e-05 Pa*s 1.636e-01 lbm/hr/ft |
fuel viscosity |
| Vaporization | |||
| Parameter = | Value | Alt Value | Description |
| chamShapeFact = | 0.6775 | chamber shape factor | |
| fracVapFuel = | 0.9838 | fraction of vaporized fuel | |
| fracVapOx = | 0.9999 | fraction of vaporized oxidizer | |
| genVapLenFuel = | 32.15 | Priem generalized vaporization length of fuel | |
| genVapLenOx = | 174.40 | Priem generalized vaporization length of oxidizer | |
| mrVap = | 1.2805 | vaporized mixture ratio | |
| rDropFuel = | 0.2149 mil |
5.46 micron 0.01 mm |
median fuel droplet radius |
| rDropOx = | 0.1274 mil |
3.24 micron 0.00 mm |
median ox droplet radius |
| Combustion Stability | |||
| Parameter = | Value | Alt Value | Description |
| cham sonicVel = | 3539.1 ft/s | 1078.7 m/s | approximate gas sonic velocity in chamber |
| fdPinjFuelReqd = | 0.10765 | minimum required fuel dP/Pc | |
| fdPinjOxReqd = | 0.128571 | minimum required oxidizer dP/Pc | |
| tauFuel = | 0.222653 ms | fuel lag time (tau/tResid=0.459066) | |
| tauOx = | 0.273101 ms | oxidizer lag time (tau/tResid=0.56308) | |
| tResid = | 0.4850 ms | residual time in chamber | |
| Acoustic Modes | |||
| Parameter = | Value | Alt Value | Description |
| 1L = | 9824 Hz | ||
| 80% of 1T = | 17480 Hz | no damping required here | |
| =====> DESIGN = | 17965 Hz | <== DESIGN IS HERE | |
| 1T = | 21850 Hz | ||
| 2T = | 36245 Hz | ||
| 80% of 1R = | 36377 Hz | baffles-only work here | |
| 80% of 3T = | 39884 Hz | cavities-only work here | |
| 1R = | 45471 Hz | ||
| 3T = | 49856 Hz | baffles + cavities OR multi-tuned cavities | |
| 3T = | 49856 Hz | <== MAX FREQUENCY... KEEP Hz HERE OR BELOW | |
| 4T = | 63103 Hz | ||
| 1T1R = | 63267 Hz | ||
| 2T1R = | 79580 Hz | ||
| 2R = | 83254 Hz | ||
| 3T1R = | 95116 Hz | ||
| 1T2R = | 101182 Hz | ||