Pingjian Ming’s research while affiliated with Sun Yat-sen University and other places

Flow-induced noise is a complex source that significantly impacts submarines' stealth performance. While previous studies have provided valuable insights into the acoustic radiation of scaled-down submarine models, addressing the flow noise of full-scale prototypes has remained a daunting challenge. To bridge this gap, the research team undertook an extensive investigation to unveil the elusive similarity law of flow noise in both small and large-scale submarine models. By leveraging computational algorithms and turbulence models, the flow field of the submarine model was simulated, and the Kirchhoff and Ffowcs Williams–Hawkings model was employed to calculate the submarine's flow noise. This comprehensive study meticulously considered various influential factors, including Mach number, Reynolds number, etc., ultimately formulating a similarity correlation formula for submarine flow noise. The findings of this study revealed several key insights, including the minimal impact of accessories on submarine flow noise similarity, the adherence of the frequency of submarine flow noise to the Helmholtz number, and the intricate relationship between sound pressure level similarity law with Mach and Reynolds number. Ultimately, this study introduces and summarizes the submarine flow noise similarity law. This law enables the estimation of real-scale model flow noise by using small-scale model flow noise as a reference.

Numerical simulations of flows with dilute disperse phase play an important role in a wide range of industrial applications. The most commonly used technique for solving such problems is the Eulerian-Lagrangian approach, in which individual particles are tracked inside the domain. However, the use of sliding and moving mesh in complex engineering applications poses more challenges for the parallelization of the Eulerian-Lagrangian method in the two-way coupling. In this context, this manuscript presents the parallel algorithm for tracking Lagrangian particles crossing sliding non-conformal interfaces in a mixed Eulerian-Lagrangian CFD algorithm, which is based on a parallel supermesh method introduced recently for the handling of sliding mesh in large-scale parallel computing (Y. Xiao and P.J. Ming, Jour. Computat. Phys., 2022). In the proposed parallel algorithm, critical problems such as geometric calculation for particles across non-conformal mesh interfaces and the dynamic communication for particle data can be handled based on the one-to-one addressing constructed by the supermesh method introduced in the author’s previous work. Further, a robust and easy-to-implement algorithm is also provided for particle communication caused by mesh moving. All methodologies are integrated and implemented for parallel computation obtaining good robustness and consistency. Specific examples are solved to examine the performance of this parallel strategy when applied to practical engineering problems.

The helical cruciform fuel (HCF) rod assembly is a new type of fuel for the lead-bismuth (LBE) fast reactor. It can be self-positioned and realize a coolant mixing without wrapped wire or grid spacer. This kind of fuel assembly can not only realize the function of the traditional wire-wrapped fuel assembly, but also omit the wire -wrapped structure, which provides a satisfactory prospect for the development of LBE reactor. In this study, the coolant mixing in the LBE cooled reactor with HCF assembly was analyzed numerically. The influence of the Reynolds number and different coolant mediums were investigated. Advantages and disadvantages of the HCF assembly were analyzed and compared with the wire-wrapped fuel.

The piston cooling of engines are usually controlled by the “cocktail shake” mechanism inside the single cooling cavity, according to most studies of piston cooling published before. This paper researched on flow in multiple cooling cavities which are extensively used on pistons of low-speed engines, revealing that the flow in multi-cavity is quite different from that in a single cooling cavity. In this work, complete reciprocating cycles are captured to study the gas-liquid two-phase flow behavior of each cavity inside the multi-cavity piston, by conducting synchronous experiments using benchmarked high-speed camera and a real size piston. The effects of different engine speeds (40–64 rpm) and different inlet pressures (0.1–0.3 MPa) were investigated. Both the inner and annular cavities are cooled mainly by cocktail shaking, but two cooling mechanisms are observed in the outer cavity, the oscillatory effect and cyclonic effect, providing further development on piston cooling studies. The cyclonic effect enhances the heat transfer capacity of the sidewall surfaces. The coupling effect between multiple cavities produces a secondary mixing effect of the liquid and improves the overall turbulence. In this paper, a comprehensive analysis of the flow mechanism within a typical multi-cavity piston is presented.