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Effect of Liquid Temperature on Surface and Mechanical Characteristics of Al-Mg Alloy Treated with a Cavitating Waterjet
Fluid Dynamics & Materials Processing 2024, 20(11): 2431-2442
Published: 30 November 2024
Abstract PDF (3.7 MB) Collect
Downloads:45

The presented study aims to reveal the effect of liquid temperature on cavitation-induced erosion of an Al-Mg alloy. An experimental work was conducted using a submerged cavitating waterjet to impact the specimen surface. For a certain cavitation number and a given standoff distance, different liquid temperatures were considered. Accordingly, a comprehensive comparison was implemented by inspecting the mass loss and surface morphology of the tested specimens. The results show that the cumulative mass loss increases continuously with the liquid temperature. A cavitation zone with an irregular profile becomes evident as the cavitation treatment proceeds. Increasing the temperature promotes the generation of cavitation bubbles. Large erosion pits are induced after severe material removal. The microhardness increases with the distance from the target surface. At a liquid temperature of 50°C, the microhardness fluctuates apparently with increasing the depth of indentation.

Issue
Cultivating interdisciplinary experimental scheme design capabilities: Taking the design of a double-slot nozzle jet impingement plate experimental platform as an example
Experimental Technology and Management 2024, 41(7): 148-153
Published: 20 July 2024
Abstract PDF (3.8 MB) Collect
Downloads:4
[Objective]

The Energy and Power Engineering major is essential for economic development and technological development, focusing on energy exploitation, conversion, and utilization. Recently, complex interdisciplinary problems have provided students with opportunities to improve their comprehensive abilities and expand their engineering perspectives. The experimental courses for this major face three significant problems: ① monotonous content; ② a disconnect between experimental projects and engineering practice; and ③ low student participation in designing experimental schemes. This study aims to design a comprehensive experimental platform that incorporates interdisciplinary knowledge, engineering cases, and innovative thinking to cultivate multi-aspect abilities.

[Methods]

The experimental scheme in this study is based on heat transfer courses arranged for Energy and Power Engineering and Material Forming and Control Engineering majors. The air cushion furnace is selected as the object of cooperation for students from different majors. As an object of engineering concern, it uses jet streams of hot air discharged from slot nozzles to anneal metal sheets. The design of the experimental platform considers the operating and geometric parameters affecting convective heat transfer, control strategies, and data processing methods. This design process requires a comprehensive application of interdisciplinary knowledge and engineering design tools. The experimental platform consists of a ventilation module, an air-injection module, a positioning module, and a data acquisition module. By setting and validating the operating parameters for each module, optimal conditions for jet impinging are determined, examining the effects of Reynolds number, air temperature, and plate speed on heat transfer.

[Results]

Using the experimental platform, flow and heat transfer parameters were measured during jet stream impinging on the plate. The process of forced convection heat transfer was described in different Reynolds numbers. In the fixed plate mode, the experimentally obtained Nusselt number distribution closely matched reported values, with a relative deviation of less than 5%. In the moving plate mode, the horizontal distribution of the Nusselt number obtained horizontally aligned well with numerical results, better reflecting engineering scenarios.

[Conclusions]

The comprehensive experimental platform designed in this study integrates multiple functional modules and allows free selection of various operating conditions. Furthermore, its modular design enables continuous upgrades and function expansions. During the development of this experimental platform, design, operation, and problem analysis were integrated. Meanwhile, the platform combines interdisciplinary knowledge, engineering elements, and control techniques to deepen students' understanding of complex engineering problems and improve their comprehensive abilities.

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