Abstract
Acomposition consisting of 80% polytetrafluoroethylene and 20% boron (by weight) was considered as a potential high-density solid fuel mixture for mixed hybrid rocket propulsive applications. Constant-pressure strand burner experiments for the given formulation indicated a low-pressure self-deflagration limit of approximately 2.2 MPa (319 psia), and a burning rate correlation rb[cm/s] = 0.042[P/MPa]/0.531 was determined. Pressurized counterflow burner experiments conducted using pure oxygen revealed formation of surface char, which prevented measurement of solid fuel regression rates below 2 MPa, indicating an additional resistance for heat and mass transfer. Static-fired rocket motor experiments, conducted to determine the pressure and flow dependencies of the system, exhibited characteristic exhaust velocity efficiencies ranging from approximately 86 to 96%.Whereas classical hybrids do not have a strong dependence of fuel regression rate on pressure, a pressure dependence was observed in this system below the low-pressure self-deflagration limit due to the pressure dependence of the decomposition and fluorination kinetics of the solid fuel mixture. Below the low-pressure self-deflagration limit, the motor operated at a constant pressure, typical of a classical hybrid, whereas above the limit, a progressive burn was observed, characteristic of a composite propellant. Systematic oxidizer dilution with nitrogen revealed a decrease in pressurization rate with decreasing oxygen content, and an ignition limit was achieved for this system when the oxygen mass fraction was reduced from 0.65 to 0.6. Characteristic exhaust velocity efficiencies were not noticeably affected by oxidizer dilution with nitrogen over the range considered.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 373-385 |
| Number of pages | 13 |
| Journal | Journal of Propulsion and Power |
| Volume | 31 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 1 2015 |
Fingerprint
All Science Journal Classification (ASJC) codes
- Aerospace Engineering
- Fuel Technology
- Mechanical Engineering
- Space and Planetary Science
Cite this
}
Boron and polytetrafluoroethylene as a fuel composition for hybrid rocket applications. / Connell, Jr., Terrence Lee; Risha, Grant Alexander; Yetter, Richard A.; Roberts, Colin W.; Young, Gregory.
In: Journal of Propulsion and Power, Vol. 31, No. 1, 01.01.2015, p. 373-385.Research output: Contribution to journal › Article
TY - JOUR
T1 - Boron and polytetrafluoroethylene as a fuel composition for hybrid rocket applications
AU - Connell, Jr., Terrence Lee
AU - Risha, Grant Alexander
AU - Yetter, Richard A.
AU - Roberts, Colin W.
AU - Young, Gregory
PY - 2015/1/1
Y1 - 2015/1/1
N2 - Acomposition consisting of 80% polytetrafluoroethylene and 20% boron (by weight) was considered as a potential high-density solid fuel mixture for mixed hybrid rocket propulsive applications. Constant-pressure strand burner experiments for the given formulation indicated a low-pressure self-deflagration limit of approximately 2.2 MPa (319 psia), and a burning rate correlation rb[cm/s] = 0.042[P/MPa]/0.531 was determined. Pressurized counterflow burner experiments conducted using pure oxygen revealed formation of surface char, which prevented measurement of solid fuel regression rates below 2 MPa, indicating an additional resistance for heat and mass transfer. Static-fired rocket motor experiments, conducted to determine the pressure and flow dependencies of the system, exhibited characteristic exhaust velocity efficiencies ranging from approximately 86 to 96%.Whereas classical hybrids do not have a strong dependence of fuel regression rate on pressure, a pressure dependence was observed in this system below the low-pressure self-deflagration limit due to the pressure dependence of the decomposition and fluorination kinetics of the solid fuel mixture. Below the low-pressure self-deflagration limit, the motor operated at a constant pressure, typical of a classical hybrid, whereas above the limit, a progressive burn was observed, characteristic of a composite propellant. Systematic oxidizer dilution with nitrogen revealed a decrease in pressurization rate with decreasing oxygen content, and an ignition limit was achieved for this system when the oxygen mass fraction was reduced from 0.65 to 0.6. Characteristic exhaust velocity efficiencies were not noticeably affected by oxidizer dilution with nitrogen over the range considered.
AB - Acomposition consisting of 80% polytetrafluoroethylene and 20% boron (by weight) was considered as a potential high-density solid fuel mixture for mixed hybrid rocket propulsive applications. Constant-pressure strand burner experiments for the given formulation indicated a low-pressure self-deflagration limit of approximately 2.2 MPa (319 psia), and a burning rate correlation rb[cm/s] = 0.042[P/MPa]/0.531 was determined. Pressurized counterflow burner experiments conducted using pure oxygen revealed formation of surface char, which prevented measurement of solid fuel regression rates below 2 MPa, indicating an additional resistance for heat and mass transfer. Static-fired rocket motor experiments, conducted to determine the pressure and flow dependencies of the system, exhibited characteristic exhaust velocity efficiencies ranging from approximately 86 to 96%.Whereas classical hybrids do not have a strong dependence of fuel regression rate on pressure, a pressure dependence was observed in this system below the low-pressure self-deflagration limit due to the pressure dependence of the decomposition and fluorination kinetics of the solid fuel mixture. Below the low-pressure self-deflagration limit, the motor operated at a constant pressure, typical of a classical hybrid, whereas above the limit, a progressive burn was observed, characteristic of a composite propellant. Systematic oxidizer dilution with nitrogen revealed a decrease in pressurization rate with decreasing oxygen content, and an ignition limit was achieved for this system when the oxygen mass fraction was reduced from 0.65 to 0.6. Characteristic exhaust velocity efficiencies were not noticeably affected by oxidizer dilution with nitrogen over the range considered.
UR - http://www.scopus.com/inward/record.url?scp=84930454713&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84930454713&partnerID=8YFLogxK
U2 - 10.2514/1.B35200
DO - 10.2514/1.B35200
M3 - Article
AN - SCOPUS:84930454713
VL - 31
SP - 373
EP - 385
JO - Journal of Propulsion and Power
JF - Journal of Propulsion and Power
SN - 0748-4658
IS - 1
ER -