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Improving the Combustion Performance of a Hybrid Rocket Engine using a Novel Fuel Grain with a Nested Helical Structure
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Untangling the Efficient Boron-Initialized Hydroxyl-Terminated Polybutadiene Combustion for High Energetic Solid
Grace L Rizzo1, Souvick Biswas1, Dongwon Ka2
1Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States.
The Journal of Physical Chemistry. A
|December 26, 2024
Summary
Boron (B) particles in hydroxyl-terminated polybutadiene (HTPB) fuel ignite spontaneously due to efficient energy transfer. This study reveals boron
Area of Science:
- Materials Science
- Combustion Science
- Chemical Engineering
Background:
- Hydroxyl-terminated polybutadiene (HTPB) is a polymer binder used in solid rocket fuels.
- Incorporating energetic boron particles into HTPB can enhance fuel performance.
- Understanding the ignition and combustion mechanisms of B/HTPB is crucial for optimizing solid rocket fuel applications.
Purpose of the Study:
- To investigate the ignition and combustion behavior of boron particles embedded in HTPB.
- To elucidate the distinct roles of boron and HTPB during the ignition process.
- To analyze the complex oxidation chemistry involved in B/HTPB combustion.
Main Methods:
- Laser-heating of levitated B/HTPB and pure HTPB particles.
- In situ spectroscopic diagnostics including Raman, infrared, and UV-Vis spectroscopy.
- Time-resolved high-speed optical and infrared imaging.
Main Results:
- Spontaneous ignition of B/HTPB observed in air, unlike pure HTPB.
- Two-stage ignition process identified: initial boron ignition followed by HTPB combustion.
- Efficient thermal energy transfer from HTPB to boron particles observed due to lower heat capacity of boron.
- Boron oxides (BO, BO2) detected as key intermediates, triggering HTPB decomposition.
- Formation of partially oxidized products like methanol and methyl vinyl ether indicates complex oxidation pathways.
Conclusions:
- Boron particles act as ignition triggers in B/HTPB solid fuels by absorbing and transferring laser energy.
- The energy released from boron ignition drives the subsequent combustion of the HTPB binder.
- Complex oxidation chemistry involving boron oxides leads to diverse combustion products, offering insights for advanced solid rocket fuel design.
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