Linear interaction analysis (LIA) is employed to investigate the interaction of reactive and nonreactive shock waves with isotropic vortical turbulence. The analysis is carried out, through Laplace-transform technique, accounting for long-time effects of vortical disturbances on the burnt-gas flow in the fast-reaction limit, where the reaction-region thickness is significantly small in comparison with the most representative turbulent length scales. Results provided by the opposite slow-reaction limit are also recollected. The reactive case is here restricted to situations where the overdriven detonation front does not exhibit self-induced oscillations nor inherent instabilities. The interaction of the planar detonation with a monochromatic pattern of perturbations is addressed first, and then a Fourier superposition for three-dimensional isotropic turbulent fields is employed to provide integral formulas for the amplification of the kinetic energy, enstrophy, and anisotropy downstream. Transitory evolution is also provided for single-frequency disturbances. In addition, further effects associated to the reaction rate, which have not been included in LIA, are studied through direct numerical simulations. The numerical computations, based on WENO-BO4-type scheme, provide spatial profiles of the turbulent structures downstream for four different conditions that include nonreacting shock waves, unstable reacting shock (sufficiently high activation energy), and stable reacting shocks for different detonation thicknesses. Effects of the propagation Mach number, chemical heat release, and burn rate are analyzed.

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The long-term thermal oxidative aging behavior of uncompressed and compressed hydrogenated nitrile rubber seals was studied in terms of the weight loss, chemical structure, crosslinking density, compression set, fracture morphology, and mechanical properties. It was found that weight loss of the uncompressed seals was more than that of the compressed seals due to restricted mobility of additives and molecular chains under compression. The ATR-FTIR results showed that hydroxyl groups and carbonyl groups both were formed under the uncompressed and compressed states, whereas only the generation of amide groups was observed under the uncompressed state. Additionally, crosslinking reactions dominated throughout the aging process, but stress-induced and oxidationinduced chain scissions occurred and competed with crosslinking during subsequent middle and later stages of aging at 110 C. Compression set of the compressed seals implied the formation of a denser network structure. The surface damage of the uncompressed seals gradually turned more serious and inhomogeneous than that of the compressed seals. Mechanical properties of the uncompressed and compressed seals showed a similar variation tendency with exposure time and degraded more seriously at higher temperatures. The TGA results indicated that the aging conditions (elevated temperature and compressive stress) did not significantly affect the thermal stability of the rubber seals.

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Surface characterization and corrosion behavior of 90/10 copper-nickel alloy in seawater from Xiamen bay at 30 °C for 56 days were investigated in this study. The results indicated that the corrosion product layer was mainly a mixture of CuO, Cu2O, and Cu(OH)2, with a transition to CuCl, CuCl2, and Cu2(OH)3Cl during the corrosion process. However, as corrosion proceeds, the resistance of the product film was reduced due to its heterogeneous and fairly porous structures, which led to local corrosion of the alloy. The corrosion potentials (Ecorr) increase while corrosion current densities (Icorr) decrease with time because of the formation of protective oxide film.