Comparative study on ignition delay time and burning rate of modified double-base propellant and fuel-rich propellant

LI, LIAN-BO; CHEN, TAO; LI, WEI-XUAN; YU, RONG-FU

doi:10.1590/0001-3765202320220762

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ENGINEERING SCIENCES • An. Acad. Bras. Ciênc. 95 (3) • 2023 • https://doi.org/10.1590/0001-3765202320220762 copy

Comparative study on ignition delay time and burning rate of modified double-base propellant and fuel-rich propellant

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

With the higher requirements of various tactical and technical indicators of the weapon systems, the current research on the ignition and combustion characteristics of different types of solid propellants is not comprehensive. In more complex and harsh environmental conditions, the pressure affects the ignition and combustion characteristics. Therefore, the paper studies the ignition and combustion characteristics of the modified double-base propellants (MDB propellants) and fuel-rich propellants (FR propellants) under low-pressure environment. Combining experiment and theory, the ignition delay time and burning rate of two kinds of solid propellants are compared and analyzed at low pressure by the laser ignition experimental device. The results displayed that the burning flames of the FR and MDB propellant presented evident V-shape and cylindrical, respectively. The flame brightness decreased with the decrease in pressure. With the increase of pressure and heat flux, the ignition delay time of the MDB propellant and the FR propellant decreased. By comparison, Model 2 of the ignition delay time was more effective for the estimation of the ignition delay time of the FR propellant. The experimental results are compared with the three burning rate models, which are the Vielle formula (Model 1), Summerfield formula (Model 2), and B-number burning rate formula (Model 3). The results showed the burning rate was more in accord with Model 3.

Key words
Burning rate; ignition delay time; fuel-rich propellant; modified double-base propellant; laser ignition

Type	Component	Mass fraction	Type	Component	Mass fraction
FR propellant	AP	36.0%	MDB propellant	HMX	50.0%
	HTPB	20.0%		NC	20.0%
	Al	20.0%		NG	20.0%
	Mg	20.0%		DNTF	6.0%
	Others	4.0%		MNA	1.0%
				Others	3.0%

Test conditions	Values
Pressure (MPa)	0.02, 0.04, 0.06, 0.08
Oxygen concentration (%)	21
External heat flux $(W / m m^{2})$	0.3, 1.2, 2.8
Inlet air temperature $(^{\circ} C)$	20

Model	Formula	Propellant type	Heat flux $(W / m m^{2})$	Fitting parameters	Correlation coefficients $R^{2}$
Model 1	$t_{ig} = a_{1} / p^{2} + b_{1}$	Fuel-rich propellants	2.8	$a_{1} = 0.04758;$	0.54926
			2.8	$b_{1} = 339.77779$	0.54926
			1.2	$a_{1} = 0.10931;$	0.79125
			1.2	$b_{1} = 461.80584$	0.79125
		Modified double base propellants	1.2	$a_{1} = 0.03668;$	0.92176
			1.2	$b_{1} = 169.55383$	0.92176
			0.3	$a_{1} = 0.05181;$	0.89917
			0.3	$b_{1} = 200.08166$	0.89917
Model 2	$t_{ig} = b_{2} - a_{2} p^{0.5}$	Fuel-rich propellants	2.8	$a_{2} = 849.06734;$	0.97334
			2.8	$b_{2} = 575.90381$	0.97334
			1.2	$a_{2} = 1732.995;$	0.981
			1.2	$b_{2} = 952.6726$	0.981
		Modified double base propellants	1.2	$a_{2} = 536.21185;$	0.91353
			1.2	$b_{2} = 323.52948$	0.91353
			0.3	$a_{2} = 771.50578;$	0.93725
			0.3	$b_{2} = 420.91489$	0.93725

Model	Formula	Propellant type	Fitting parameters	Correlation coefficients $R^{2}$
Model 1	$\dot{r} = a_{v} \cdot p^{n}$	Fuel-rich propellants	$a_{v} = 1.89199$ ;	0.87149
		Fuel-rich propellants	$n = 0.30628$	0.87149
		Modified double base propellants	$a_{v} = 1.73397$ ;	0.88397
		Modified double base propellants	$n = 0.31436$	0.88397
Model 2	$\frac{1}{\dot{r}} = \frac{a_{s}}{p} + \frac{b_{s}}{p^{\frac{1}{3}}}$	Fuel-rich propellants	$a_{s} = - 0.00402$ ;	0.88547
		Fuel-rich propellants	$b_{s} = 0.51813$	0.88547
		Modified double base propellants	$a_{s} = - 0.0035$ ;	0.89296
		Modified double base propellants	$b_{s} = 0.57142$	0.89296
Model 3	$a_{B} + b_{B} {(p^{1 / 2})}^{c}$	Fuel-rich propellants	$a_{B} = 0.59902$ ;	0.99479
			$b_{B} = 25.57062$ ;
			$c = 3.64037$
		Modified double base propellants	$a_{B} = 0.52717$ ;	0.98278
			$b_{B} = 18.86254$ ;
			$c = 3.44577$

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[1] Correspondence to: Tao Chen E-mail: 2020101116@niit.edu.cn