Search

Numerical simulations were performed to study the influence of the inside diameter of the pulse separation device port on the flow features and the local heat transfer characteristics in a dual pulse solid rocket motor. A lower–upper symmetric Gauss–Seidel implicit dual time-stepping method was applied to address the problem of unsteady flow. A high-resolution upwind scheme (AUSMPW+) and Menter’s shear stress transport turbulence model were employed to solve the Reynolds-averaged Navier–Stokes equations. The conjugate heat transfer strategy was realized by enforcing a common temperature and heat flux at the fluid–solid interface. After validating the accuracy and reliability of the numerical algorithm by comparison with experimental cases, the internal flow of a dual pulse solid rocket motor was simulated. The results show that the magnitude of the velocity, the wall shear stress, and the turbulent kinetic energy downstream of the pulse separation device port decrease with increasing pulse separation device port diameter. The local heat transfer coefficient increases sharply downstream of the pulse separation device port, reaching a maximum within 1–2 diameters downstream of the pulse separation device port, before relaxing back to the fully developed pipe flow value. The peak value of the local heat transfer coefficient reduces as the pulse separation device port diameter increases. Meanwhile with an increasing pulse separation device port diameter, the position of the peak local heat transfer coefficient moves upstream to the head of the first pulse chamber, and appears upstream of the position of the reattachment point by an average of about 28.6%. [ABSTRACT FROM AUTHOR]

One of the most challenging requirements in a solid rocket motor (SRM) is the integrity of the charge structure which is a multilayer adhesive joint involving the propellant, liner, and insulation. The propellant/liner/insulation interface is considered to be the weakest part of the whole structure. This interface has some of the usual features of an adhesively bonded interface, as well as its own special characteristics: the co-cured process, ingredient migration between interfaces, and complicated damage mechanisms. We give a technical and critical review of the past 50 years of existing research on many aspects of the propellant/liner/insulation interface in terms of the adhesive properties and adhesive mechanisms, ingredients migration, damage determination, and fracture analysis. To present a comprehensive outline of this interface we also clarify some remaining problems which should be addressed in the future. With significant improvements in the theoretical and experimental studies of the propellant/liner/insulation interface, the problem of integrity failure of the charge structure in SRM will be well resolved. [ABSTRACT FROM AUTHOR]

Batch experiments were conducted to study the ability of activated palm kernel husk carbon (APKHC) to adsorb Pb(II) ions from aqueous solutions. The effects of various operational parameters, such as temperature (25–55°C), pH (1.0–5.0), contact time (0–120 min), and adsorbent dose (0.5–3.5 g/L) were examined. The results suggested that the adsorption of Pb(II) is exothermic and strongly dependent on pH. The optimum pH for Pb(II) removal is 5.0. The Pb(II) uptake by APKHC was fast and reached an equilibrium in 80 min. The Pb(II) removal efficiency increased with increasing APKHC dosage up to 2.0 g/L, and then reached a plateau with approximately 97% of Pb(II) removed. Experimental data were fitted using Langmuir and Freundlich isotherms. The Pb(II) adsorption can be described well by the Langmuir model with a maximum monolayer uptake capacity of 98.04 mg/g. Kinetic study results suggested that the adsorption process proceeded according to the pseudo-second-order kinetic model. In short, APKHC can be used as an effective economical adsorbent for Pb(II) removal. [ABSTRACT FROM PUBLISHER]