Summary of Experimental Data

Experimental data have been obtained on detonations for mixtures that have not been previously studied. For convenience, we summarize these data in Table 2. The diluent amount required to reach a cell width of 100 mm has been estimated by interpolating or extrapolating the experimental data.

 

Table 2: Summary of measured cell width data (initial pressure of 100 kPa).

Mixture	Diluent	(%)	$\lambda$
			(mm)
H2 + 1/2O2	-	0	1.3-2.0
	N2	55	10-15
H2+N2O	-	0	1.5
	N2	62	36
	air	65	26
CH4+2O2	-	0	3
	N2	72	300
CH4+4N2O	-	0	3(*)
	N2	64	80
	air	60	50
NH3+ 3/4O2	-	0	16-25
	N2	35	100
NH3+ 3/2N2O	-	0	6(*)
	N2	38	34(*)
	air	53	64(*)
(*) Extrapolated from lower pressure.

Comparison of results without dilution show that cell widths for H₂ and CH₄ are slightly smaller with O₂ as the oxidizer than with N₂O. The situation is reversed in NH₃, which has a smaller cell width (24 mm vs 40 mm) with N₂O as an oxidizer than with O₂.

All of the mixtures with the exception of the model SY-101 composition demonstrate increasing cell widths with increasing diluent concentration. The SY-101 mixtures show a constant or slightly decreasing cell width with increasing air concentration up to about 40% dilution, then the cell width rises sharply with increasing dilution. This is a consequence of these mixtures being fuel rich.

Air dilution results in slightly smaller cell widths than N₂ dilution for both H₂ and CH₄ mixtures. This effect is not discernible in the NH₃-N₂O data. The amount of diluent required to obtain a cell width of 100 mm is about 60 to 70% in all cases except for the NH₃-O₂ mixture which only requires about 35% N₂. The ammonia mixture has substantially (one order-of-magnitude) larger cell widths than either the H₂ or CH₄ mixtures. Using N₂O instead of O₂ results in substantially smaller cell widths for NH₃, suggesting a direct channel of reaction that is not present in either H₂ or CH₄.

The original SY-101 mixture has a cell width of 100 mm at a dilution of about 75% air, however the revised composition only requires 60% dilution to reach a the same cell width.