Post by rayrocketman on Jan 4, 2020 0:44:38 GMT
1. Determine the flow rate required:
Wdot = flow rate in lb/sec
Thrust = 300 lbs
Efficiency = 0.96
Isp = 117.6 (300 psi chamber, sea level exhaust)
Wdot = Thrust /(Isp * efficiency)
Wdot = 300 lb /s(117.6 * 0.96)
Wdot = 2.6573 lb/sec
2. Calculate the catalyst screen diameter:
Frontal area (spquare inches) = Wdot*60/L.F.
The initial reference specifies loading factors (L.F.) are inversely proportional to peroxide temperature and range from 5-114.
The example equation uses a value of 20 for operation between 50 and 70 degree F.
Frontal area = (2.6573*60)/20
= 7.9719 square inches
Divide by π, take the square root and multiply by two to get a screen diameter of 3.186 inches.
The first reference recommends sixty silver screens (or silver plated), 40 x 40 mesh, treated with samarium oxide, interference fit to the inner chamber bore between 0.002" and 0.010", backed up with an equal amount of monel screens. This pack has an anti-channeling ring of annealed 1/32" stainles steel at the top and 20 silver screens down. It should have a 0.002" interference fit for a 3" catpack. The entire pack is compressed to between 1800 and 3000 psi to a thickness of 1 3/8" retained by an upper and lower perforated stainless steel support plate.
Above the catpack is the upper support plate, which is a perforated stainless disk with between 20 and 25% open area, the holes 1/32" to 1/8" diameter. A number of stainless steel dowels between the chamber head and the upper support plate to keep it from bowing as the silver screens heat and expand.
The lower screen support plate should be similarly perforated and is supported with a gusset web welded to the underside.
Flight time:
95% H2O2 has a density of 1.42 g/cc; thus 5 gallons of H2O2 would weigh 59.214 pounds and can provide 300 pounds thrust for 22.284 seconds. Most of the flight would be using propellant at a lower rate, flight time would correspondingly increase.
References:
Design Of Catalyst Packs For The Decomposition Of Hydrogen Peroxide
Noah S. Davis, Jr, James c. McCormick
arc.aiaa.org/doi/abs/10.2514/5.9781600864759.0589.0616
Investigation of catalyst beds for 98-percent-concentration hydrogen peroxide
Jack F. Runckel, Conrad M. Willis, and Leland B. Salters, Jr.
catalog.hathitrust.org/Record/011449060
Development of Hydrogen Peroxide Monopropellant Rockets
Cervone, et al
www.esa.int/gsp/ACT/doc/PRO/ACT-RPR-PRO-JPC2006-HP%20Rockets%202006-5239.pdf
Study of Silver Catalyst Packing for a low-thrust Hydrogen Peroxide Monopropellant Thruster
Chan, Yung-An & Hsu, Hung-Wei & Chen, Gung-Bun & Chao, Y.-C. (2010)
www.researchgate.net/publication/280013169_Study_of_Silver_Catalyst_Packing_for_a_low-thrust_Hydrogen_Peroxide_Monopropellant_Thruster
Catalyst development for hydrogen peroxide rocket engines
P. Morlan, P.-K. Wu, D. Ruttle, R. Fuller, A. Nejad and W. Anderson
doi.org/10.2514/6.1999-2740
Wdot = flow rate in lb/sec
Thrust = 300 lbs
Efficiency = 0.96
Isp = 117.6 (300 psi chamber, sea level exhaust)
Wdot = Thrust /(Isp * efficiency)
Wdot = 300 lb /s(117.6 * 0.96)
Wdot = 2.6573 lb/sec
2. Calculate the catalyst screen diameter:
Frontal area (spquare inches) = Wdot*60/L.F.
The initial reference specifies loading factors (L.F.) are inversely proportional to peroxide temperature and range from 5-114.
The example equation uses a value of 20 for operation between 50 and 70 degree F.
Frontal area = (2.6573*60)/20
= 7.9719 square inches
Divide by π, take the square root and multiply by two to get a screen diameter of 3.186 inches.
The first reference recommends sixty silver screens (or silver plated), 40 x 40 mesh, treated with samarium oxide, interference fit to the inner chamber bore between 0.002" and 0.010", backed up with an equal amount of monel screens. This pack has an anti-channeling ring of annealed 1/32" stainles steel at the top and 20 silver screens down. It should have a 0.002" interference fit for a 3" catpack. The entire pack is compressed to between 1800 and 3000 psi to a thickness of 1 3/8" retained by an upper and lower perforated stainless steel support plate.
Above the catpack is the upper support plate, which is a perforated stainless disk with between 20 and 25% open area, the holes 1/32" to 1/8" diameter. A number of stainless steel dowels between the chamber head and the upper support plate to keep it from bowing as the silver screens heat and expand.
The lower screen support plate should be similarly perforated and is supported with a gusset web welded to the underside.
Flight time:
95% H2O2 has a density of 1.42 g/cc; thus 5 gallons of H2O2 would weigh 59.214 pounds and can provide 300 pounds thrust for 22.284 seconds. Most of the flight would be using propellant at a lower rate, flight time would correspondingly increase.
References:
Design Of Catalyst Packs For The Decomposition Of Hydrogen Peroxide
Noah S. Davis, Jr, James c. McCormick
arc.aiaa.org/doi/abs/10.2514/5.9781600864759.0589.0616
Investigation of catalyst beds for 98-percent-concentration hydrogen peroxide
Jack F. Runckel, Conrad M. Willis, and Leland B. Salters, Jr.
catalog.hathitrust.org/Record/011449060
Development of Hydrogen Peroxide Monopropellant Rockets
Cervone, et al
www.esa.int/gsp/ACT/doc/PRO/ACT-RPR-PRO-JPC2006-HP%20Rockets%202006-5239.pdf
Study of Silver Catalyst Packing for a low-thrust Hydrogen Peroxide Monopropellant Thruster
Chan, Yung-An & Hsu, Hung-Wei & Chen, Gung-Bun & Chao, Y.-C. (2010)
www.researchgate.net/publication/280013169_Study_of_Silver_Catalyst_Packing_for_a_low-thrust_Hydrogen_Peroxide_Monopropellant_Thruster
Catalyst development for hydrogen peroxide rocket engines
P. Morlan, P.-K. Wu, D. Ruttle, R. Fuller, A. Nejad and W. Anderson
doi.org/10.2514/6.1999-2740