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The fluidal jet turbulator has been a novel perturbation generator in the pulse-detonation engines research field for the past few years. In this paper, an experiment is performed to study the deflagration to detonation transition (DDT) process in a detonation chamber with a reactive transverse methane-oxygen mixture jet in crossflow (JICF). The jet injection arrangement is fundamentally investigated, including single jet and various double jets patterns. Corresponding two-dimensional direct numerical simulations with a multistep chemical kinetics mechanism are employed for analyzing details in the flow field, and the interaction between the vortex and flame temporal evolution is characterized. Both the experiments and simulations demonstrate that the JICF can distinctly accelerate flame propagation and shorten the DDT time and distance. The vortex stream induced by the jet distorts and wrinkles the flame front resulting in local flame acceleration. Moreover, the double jet patterns enhance flame acceleration more than the single jet injection because of the intrinsic counterrotating vortex pairs and enhanced turbulence intensity.

A new induction heating tundish with bent channels is presented as a solution to the lower efficiency of heating and inclusion removal in the traditional straight channels induction heating tundish. By Euler-Lagrange method, a three-dimensional unsteady-state mathematical model is built to compare the motion and the removal of inclusions in the two types of tundishes. In addition, the mathematical model for the inclusions collisiongrowth under the induction heating condition is also established based on the force balance. The results show that, compared with the traditional tundish, the turbulence intensity of liquid steel is higher in the channels of the new tundish and quite uniformly distributes in the discharging chamber. For those lower-sized inclusions smaller than 50 mm, the channels in the new tundish have a significantly higher inclusion removal rate than those in the traditional tundish, and the most inclusions absorbed by the channels of the traditional tundish are in the size range of 50-60 μm, while they are 50-60 μm and 60-70 μm for the new tundish. For each of the seven inclusion sizes, the removal rate of inclusions in the new tundish is quite higher than that in the traditional tundish. Compared to the traditional tundish, the inclusions removed in other areas in the new tundish are lower than those removed by the channels. When inclusions of all seven sizes are put into the two tundishes, the inclusions removal rate in the new tundish is also significantly higher than that in the traditional tundish. Under the same heating power, the new tundish is more efficient than the traditional tundish on inclusions removal.

The interface properties between surface grown carbon nanotubes carbon fiber (CNTs-CF) and epoxy resin were investigated by different modification methods. The X-ray photoelectron spectrometer probations show that the pristine CNTs-CF has very low contents of both oxygen element and active carbon element. Taking the naked carbon fiber (CF) without CNTs grown as a reference, the interfacial shear strength (IFSS) of CNTs-CF/epoxy is only 5.6% higher. After heat treatment, chemical modification and sizing treatments, the surface chemical activity of CNTs-CF is improved considerably. In contrast with the IFSS of standard CF/epoxy, the interfacial strength of chemical-treated CNTs-CF-E1/ epoxy is increased to 122.8 MPa by 29.7%. The increasing content of the epoxy active groups at the modified CNTs-CF-E1 surface is conducive to forming covalent bonds between the epoxy resin and the CNTs-CF-E1 surface particularly the activated nanotube surface. The enhancement of CNT/epoxy interface is beneficial to the over whole interface property of the composites. Hence, the compressive and torsion strength of sizing CNTs-CF-E1 bundle combined with epoxy resin are increased by 32.4% and 14.1%, respectively. The SEM images show the failure morphologies of different modification methods, and the enhancement mechanism of multiscale interface is further clarified. Compared with chemical treatment, heat treatment can remove the inert amorphous carbon on the CNTs-CF fiber surface and improve the interface adhesion of CNT/epoxy and CF/epoxy, and surface sizing treatment improves the CF/epoxy interface. The enhancement mechanisms of these modified CNTs-CFs/epoxy should be ascribed to the competition and synergetic effects of the multiscale interfaces, including CNT/CF, CNT/epoxy, and CF/epoxy.