Numerical simulation of stability of diffusion depth of deterrents into cylindrical nitrocellulose composite under different conditions

Abstract

In this study, evaluation and prediction of diffusion depth of deterrents of Butyl-NENA and Polyethylene-glycol-di-methacrylate into the propellant and the effect of different conditions on diffusion stability, such as variations of concentration, temperature and aging with time, were performed by using COMSOL Multi-physics 4.4 to lower the laboratory costs and saving time. Diagrams indicated that diffusion of deterrents occurs to a certain depth of the propellant radius and variations of concentration in allowed ranges, does not affect the final diffusion depth significantly. Also, variations in temperature and aging with time had a little effect on the diffusion depth. Results showed that substances were used for nitrocellulose propellant coating, have excellent diffusion stability. simulation results were compared torelated experimental results and showed good agreement with them. concentration profiles of Butyl-Nena at two concentrations of 10% and 20%, measured at 70˚C for 10 h. the concentration profile at 10% is shown, and a gentle increase in concentration is observed for small to medium radii. While the 20% profile shows a faster and more significant increase in concentration, reaching high values at larger radii. These results indicate a significant effect of Butyl-Nena concentration on its concentration distribution pattern with increasing radius. the concentration profiles of deterrent polymers at two concentrations of 2% and 12%, measured at 70˚C for 10 h. the deterrent concentration at 2% gradually increases and reaches significant values, while at 12%, the concentration rapidly approaches a maximum value. These results indicate a significant effect of deterrent concentration on the concentration profiles with increasing radius.The aim of the present work was predicting the influence of various conditions such as, concentration, temperature and time on deterrents diffusion stability by COMSOL Multi-physics.

Keywords: COMSOL Multi-physics; Deterrent; Diffusion; Nitrocellulose; Simulation; Stability.

Fig. 1

A meshviewgenerated in two-dimensionalmodel

Fig. 2

Concentration profiles of 10% Butyl-Nena interms of nitrocellulose radius in different temperaturesfor 4 h. (a) 40 ° C, (b) 50 ° C, (c) 60 ° C, (d) 70 ° C

Fig. 3

Concentration profiles of 2% polymeric deterrent interms ofnitrocellulose radius in different temperaturesfor 4 h. (a) 40 ° C, (b) 50 ° C, (c) 60 ° C, (d) 70 ° C

Fig. 4

Concentration profiles of 10–20% Butyl-Nena in terms of nitrocellulose radius at 70˚C for 4 h. (a) 10% Butyl-Nena, (b) 12% Butyl-Nena, (c) 14% Butyl-Nena, (d) 16% Butyl-Nena, (e) 18% Butyl-Nena, (f) 20% Butyl-Nena

Fig. 5

Concentration profiles of 2–12% polymeric deterrent in terms of nitrocellulose radius at 70˚C for 4 h. (a) 2% polymeric deterrent, (b) 4% polymeric deterrent, (c) 6% polymeric deterrent, (d) 8% polymeric deterrent, (e) 10% polymeric deterrent, (f) 12% polymeric deterrent

Fig. 6

Concentration profiles of (a) 10 and (b) 20% Butyl-Nena in terms of radius of propellant at 70˚C for 10 h

Fig. 7

Concentration profiles of (a) 2 and (b) 12% polymeric deterrent in terms of radius of propellant at 70˚C for 10 h

Fig. 8

Concentration profiles of deterrent DBP in a single phase propellant. Measured concentration values (dots) and recalculated concentration profile (lines: obtained by fitting the measured values to the model) for t0 (un-aged propellant) and t1 (propellant stored at 71˚C for 28 days). Fitted D value: 0.05.10–15 m2/s [14]

Fig. 9

Resulted diagrams obtained from simulation of DBP deterrent diffusion into the spherical propellant. (a) DBP deterrent diffusion at 70˚C for t0 (un-aged propellant), (b) DBP deterrent diffusion at 71˚C for 28 days

Fig. 10

Concentration profiles of polymeric deterrent “A” in a double based propellant. Measured concentration values (dots) and recalculated concentration profile (lines: obtained by fitting the measured values to the model) for t₀(un-aged propellant) and t₁ (propellant stored at 71˚C for 28 days). Fitted D value: 0.13.10^− 15 m²/s [24]

Fig. 11

Resulted diagrams obtained from simulation of DBP deterrent diffusion and the polymeric deterrent “A” diffusion into the spherical propellant. (a) polymeric deterrent “A” diffusion for t₀ (un-aged propellant), (b) Polymeric deterrent “A” diffusion at 71˚C for 28 days