Intrinsic combustion instability of solid energetic materials

Nonlinear Intrinsic Instability of Solid Propellant Combustion Including Gas-Phase Thermal Inertia

“…But it is argued that QSHOD results are not valid at high pressures (p > 50 atm). In this section the present numerical results are compared with the closed-form expressions of De Luca, et al, (1995) for properties given in Table II, which are typical of high-pressure burning, 03 = 0.044. The lalter consider linear, QSHOD theory for pressure-driven burning, and obtain closed-form expressions for &i?p(llc) and 0(Qc)' De Luca et al, consider three simplistic but different models for the gas-phase heat-release profile.…”

“…The FM approach was evolved and developed in the United States while the ZN method was pioneered mainly within the former Soviet Union. The equivalence of different QSHOD models, both FM and ZN approaches, has been demonstrated by Culick (1968), Son (1993) andDe Luca, et al, (1995).…”

“…Therefore, a fully transient burning model should consider the unsteadiness of the condensed phase, burning surface and the gas phase all together. As discussed before, the QSHOD model considers unsteadiness of the condensed phase only, and hence, its validity is restricted to pressure perturbations in a low-frequency range of below some I kHz (Denison and Baum, 1961;T'ien, 1972;De Luca et al, 1995) and to cases where the indirect effect of adiabatic compression on the gas-phase energy release can be neglected (Clavin and Lazimi, 1992). Further, it is impossible to consider the effect of intrinsic gas-flaine instability on the stability of the deflagrating solid with QSHOD models (Margolis and Williams, 1988).…”

“…Secondly, the assumption of small perturbations made by many models may give rise to errors when applied to problems where the change in conditions results in considerable nonlinearities. Apart from Krier et al, (1968), Brown andMuzzy (1970) andDe Luca et al, (1995), all studies till now, both quasi-steady and transient gas-phase, have used the assumption of small perturbations. It has been experimentally observed (Eisel, 1964) that the finite-amplitude pressure fluctuations reduce the mean burning rate in a wide range of frequencies (up to 10kHz), where the quasi-steady gas-phase assumption is not valid.…”

“…The code was validated for steady burning over a range of ambient pressures and temperatures (Anil Kumar, et a/., 1997). The physico-chemical properties and practical operating conditions vary over a wide range of values, and therefore to help quantitative comparison, only the representative values for a model propellant as listed by De Luca, et al, (1995) were identically taken for the present calculations. Typical values are shown in Table II.…”