Abstract
Temperature control is an important limitation to further increase in geotechnical centrifuge power. Although vacuum pumps can reduce windage loss, they also negatively affect heat transfer performance. Therefore, in this study, we aim to accurately determine the rate at which windage loss decreases with pressure to help assess whether reducing pressure is beneficial to temperature control. A computational fluid dynamic method based on the multi-reference model and k–ω shear-stress transport turbulence model is used to simulate the ZJU400gt geotechnical centrifuge. The windage loss and temperature of ZJU400 at 0–150 gravity acceleration under normal pressure conditions are simulated. Compared with the experimental data, the error is < 20.7%, indicating simulation reliability. Furthermore, the simulation model is used to simulate the windage loss power under low-pressure conditions and predict the relationship between the windage loss power and pressure. Compared with current calculation methods, which yield a linear relationship between windage loss and operating pressure, the simulation results indicate a slightly nonlinear relationship. At 5,000 Pa, the simulated windage loss is 40% larger than the calculated value, severely affecting the temperature control design. Moreover, the velocity exhibits minimal variation with pressure, whereas the effective kinematic viscosity varies substantially. The nonlinear relationship between the windage loss and pressure can be attributed to increased turbulent kinetic energy and the size of the wake region caused by vacuum pumping. A formula for nonlinear windage loss with pressure is proposed, providing a basis for the future design of super-gravity geotechnical centrifuges.
Highlights
1.1 BackgroundGeotechnical centrifuges enable the observation of movement processes in multi-phase media, such as rock and soil, deep earth materials, and alloy melts within a supergravity environment
The trend and values of the simulated windage loss agree well with the measured data, confirming the validity of the simulation results. These results indicate that the computational fluid dynamic (CFD) model produces good simulation results for ZJU400, such that the model can be used to analyze windage loss under different pressures. 3.2 Correlation between windage loss and pressure CFD simulations were conducted under operating pressures of 5000, 10,000, 20,000, 50,000, and 101,325 Pa and under acceleration conditions of 30, 60, 90, and 120 g
3.4.1 Effective dynamic viscosity versus pressure for the 1,500-g high-speed centrifuge CHIEF project under construction in Zhejiang University, the windage loss can be reduced to the megawatt level via vacuum pumping
Summary
Geotechnical centrifuges enable the observation of movement processes in multi-phase media, such as rock and soil, deep earth materials, and alloy melts within a supergravity environment. They provide the primary conditions for the construction of major infrastructure, development of deep-sea resource, and research and development of high-performance materials [1,2,3,4]. The maximum acceleration of the CHIEF high-speed centrifuge at 1000 kg will be 1500 g, with a radius of 4.5 m and a motor power exceeding 5000 kW at atmospheric pressure. The CHIEF high-speed centrifuge will have five-fold more power and 4.3-fold more acceleration than the centrifuge in the ERDC, representing a substantial improvement in the performance of existing geotechnical centrifuges
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