e corrosion behavior of Alloy C-276 in high-temperature and high-pressure water at 500°C and 25 MPa, respectively, was investigated by means of mass gain, scanning electron microscopic observation, and X-ray diffraction. e results indicated that the mass gain rate of Alloy C-276 in supercritical water obeys the parabolic law. e oxide scale was formed on Alloy C-276 with a dual-layer structure, mainly consisting of an outer Ni-rich layer and an inner Cr 2 O 3 /NiCr 2 O 4 mixed layer. Tiny microcracks can also be found in the oxide scale if exposed for longer time. Meanwhile, higher temperature promotes oxide rate and results in thermal stress in the oxide film.

A marine gas turbine enclosure must be designed to prevent overheating of the electrical and engine control components as well as diluting potential fuel leaks. In order to achieve an optimal enclosure design, a numerical study of the ventilation-ejection cooling mechanism of a gas turbine enclosure is carried out in this paper. The evaluation index of the ejection cooling performance is first proposed and the algorithm of numerical simulation is verified. On this basis, orthogonal combinations of structural parameters are carried out for the expansion angle α of the lobed nozzle and the spacing S between the outlet plane of the lobed nozzle and the inlet plane of the mixing tube. The flow and the temperature distribution inside the enclosure are analysed under different operating conditions. The results show that the influence of the lobed nozzle expansion angle α and the spacing S on the performance is not a single-valued function but the two influencing factors are mutually constrained and influenced by each other. For any spacing, the combined coefficient is optimal for the expansion angle α = 30°. When the expansion angle α = 45° and the spacing S = 100 mm, the combined coefficient and the temperature distribution inside the enclosure are optimal at the same time.

Wf/Zr-based amorphous matrix composite is supposed as a potential penetrator material of armor-piercing projectile because it has both advanced piercing performance and environmentally friendly property, and it becomes the hot spot of science study and engineering application. To get a deeper understand of the penetration mechanism and the influence of temperature rise on structure of target, target which is penetrated by penetrator made of Wf/Zr-based amorphous matrix composite is studied by SEM and micro-hardness tester. Oxidation of back of target is severe, and Martensite transformation happens around the crater. From the crater surface to the interior of the steel target, the section can be divided into 3 layers: the Martensite layer, the deformed fine grain layer and the normal matrix. Martensite transformation indicates the target steel around crater is heated and softened in penetration, so this phenomenon is beneficial to penetrate and get a deeper understand of the penetration mechanism. CLC: TJ04 Document code: A

The high-temperature exhaust gases and the hot surfaces of the ejector device in marine gas turbines generate significant levels of infrared radiation. An appropriate nozzle structure can effectively lower the exhaust gas temperature and reduce the high-temperature radiation surface area, thereby minimizing external infrared radiation. In this study, a numerical simulation of the nozzle structure in the ejector device was conducted using computational fluid dynamics (CFD) methods. By investigating the orthogonal combinations of nozzle inclination angles and the number of nozzles, the temperature distribution and flow characteristics under different operating conditions were analysed. The results showed that as the nozzle inclination angle increased, the entrainment coefficient (Ce) and the temperature ratio at the inlet and outlet (Rt) initially improved but then worsened. Simultaneously, the pressure loss coefficient (Cpl) increased with the inclination angle. The CRITIC weight method was employed to objectively allocate weights to Rt, Ce, and Cpl, determining the optimal solution. The results indicated that Rt and Cpl had significant and similar weights. The optimal solution was found in Case 10 (α = 5°, x = 4), with corresponding evaluation indices of Ce=2.38, Cpl=11.45, and =0.68. This study's findings are of great importance for enhancing the performance of marine gas turbines and reducing external infrared radiation.

In this paper, the preparation of Ni–Ti–Nb amorphous alloy materials made by mechanical alloying method has been studied. The Ni–Ti–Nb mixed powders obtained by different mechanical alloying times have been analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the Ni–Ti–Nb mixed powders can be mechanically alloyed after milling for 10 hours, and retained with ball milling. Continuously, Ni, Ti and Nb alloy powders diffuse with each other. When the diffusion rate increases to a certain extent, it is too late to form an ordered structure and form a Ni–Ti–Nb amorphous alloy. The stress and displacement curves are obtained by testing the tensile strength at room temperature. The stress changes of the restrained curves are relatively stable when the displacement is 6–18 mm, and the stress changes of the unconstrained curves show a distinct upward trend when the displacement is 6–18 mm, indicating that the strength of the specimens treated with restraint is higher than that of the specimens treated with restraint. This is due to the high internal stress of the material caused by the restraint and the decrease in the tensile strength of the alloy material.