Distributed Ignition Using Single-Walled Carbon Nanotubes (SWCNTs) with Applications in Aerospace and Future Automotive Engines

Ignition characteristics of SWCNTs with an ordinary camera flash are reported here. The ultimate goal of the work is to use SWCNT or other nanostructured materials as a means for distributed ignition in liquid rocket fuel sprays and homogeneous-charged compression ignition (HCCI) engines. The idea was originally proposed by the author in April 2003 and patented after initial investigation. Based on the initial results, it is believed that this approach enables volumetric and distributed ignition of liquid fuel sprays as was demonstrated in gaseous fuel-air mixtures. This means remote and spatial ignition within any desired region defined by the shape of the light emanating from the light source. Initial investigation reported here was concentrated on the effects of different incident light source pulse widths on minimum ignition energy (MIE) from 350-1500 nm, effects of degree of sample compactness (packing) on the ignition characteristics, effects of percent iron (Fe) content of the SWCNTs samples, and initial measurements of sound pressure level (SPL) from the photo acoustic phenomenon. Results indicate that progressively lower energy/pulse is needed to initiate ignition by shortening the flash pulse duration. For example, at pulse width of ~0.2ms, it required ~30-35 mJ/pulse to initiate ignition of the un-compacted samples in standard air whereas at ~7ms duration it needed ~80-90 mJ/pulse to achieve the same results. For lightly-compressed samples, MIE trend remains unchanged; otherwise, increases with increased compression. Results also suggest that samples with an Fe (nanometallic particle) content as low as 18% (by weight) can be ignited in air with the utilized camera flash in the reported experimental setup.