In aerostatic thrust bearings (ATBs), a high-pressure gas film with a certain bearing capacity and stiffness is formed by passing high-pressure gas between the moving surface and the static surface. Aerostatic bearings have outstanding advantages in the following aspects: high precision, high speed, and long service life, etc. They are widely used in many fields, such as high-speed air spindles, precision machine tools, air-bearing guideways, turbine machinery, and high-speed drills. With the pursuit of higher efficiency and high-precision machining machinery, there is an increasing demand for high-performance ATBs. Much effort has been spent on the study of ATBs, such as improvements in load capacity and stiffness, and the enhancement of stability. Some significant progress has been achieved. In this paper, the research developments of ATBs are summarized from several aspects, such as theoretical models and experimental methods, static performance, dynamic performance, and applications. In addition, insights on the breakthrough and development trends of ATBs are put forward. It is hoped that this paper can provide some guidance for the design and application of ATBs.

Gas foil bearing has been widely used in high-speed turbo machinery due to its oil-free, wide temperature range, low cost, high adaptability, high stability and environmental friendliness. In this paper, state-of-the-art investigations of gas foil bearings are reviewed, mainly on the development of the high-speed turbo machinery in China. After decades of development, progress has been achieved in the field of gas foil bearing in China. Small-scale applications of gas foil bearing have been realized in a variety of high-speed turbo machinery. The prospects and markets of high-speed turbo machinery are very broad. Various high-speed turbomachines with gas foil bearings have been developed. Due to the different application occasions, higher reliability requirements are imposed on the foil bearing technology. Therefore, its design principle, theory, and manufacturing technology should be adaptive to new application occasions before mass production. Thus, there are still a number of inherent challenges that must be addressed, for example, thermal management, rotor-dynamic stability and wear-resistant coatings.

With the rapid development of information technology, researchers have paid attention to the pump-driven two-phase cooling loop technology for data centers, which imposes requirements on the efficiency and size of the pump. A fluid self-lubricating centrifugal pump with R134a refrigerant was developed to reach a higher rotation speed and oil-free system, resulting in a more diminutive size. Due to the high rotation speed and refrigerant pressure approaching saturated vapor pressure, the internal flow characteristics and cavitating characteristics are critical and complex. This paper focuses on the prototype’s head and cavitation performance based on experimental and numerical data. The experiments indicated that the head coefficient of the pump under design conditions is 0.9881, and the pump’s critical cavitation number and breakdown number are 0.551 and 0.412, respectively. The numerical results can predict the head and cavitation with deviations less than 2.6%. To study changing patterns in flow characteristics under the different operating conditions in the refrigerant centrifugal pump, the numerical model based on a modified Sauer-Schnerr cavitation model was built to analyze the distributions of pressure, temperature, relative velocity, and bubble volume across every hydraulic component and different degrees of cavitation, and proposed the influence of the thermal effect on refrigerant cavitating. The cavitating flow characteristics were obtained with the aim of providing guidance for the hydraulic design of a refrigerant centrifugal pump.

The rapid development of industrial and information technology is driving the demand to improve the applicability and hydraulic performance of centrifugal pumps in various applications. Enhancing the rotational speed of pumps can simultaneously increase the head and reduce the impeller diameter, thereby reducing the pump size and weight and also improving pump efficiency. This paper reviews the current application status of high-speed pumps using low-temperature thermosensitive fluids, which have been applied in fields such as novel energy-saving cooling technologies, aerospace, chemical industries, and cryogenic engineering. Due to operational constraints and thermal effects, there are inherent challenges that still need to be addressed for high-speed pumps. Based on numerical simulation and experimental research for different working fluids, the results regarding cavitation within the inducer have been categorized and summarized. Improvements to cavitation models, the mechanism of unsteady cavity shedding, vortex generation and cavitation suppression, and the impact of cavitation on pump performance were examined. Subsequently, the thermal properties and cavitation thermal effects of low-temperature thermosensitive fluids were analyzed. In response to the application requirements of pump-driven two-phase cooling systems in data centers, a high-speed refrigerant pump employing hydrodynamic bearings has been proposed. Experimental results indicate that the prototype achieves a head of 56.5 m and an efficiency of 36.1% at design conditions (n = 7000 rpm, Q = 1.5 m³/h). The prototype features a variable frequency motor, allowing for a wider operational range, and has successfully passed both on/off and continuous operation tests. These findings provide valuable insights for improving the performance of high-speed refrigerant pumps in relevant applications.

Compared with large centrifugal air compressors, the flow rate and operating range of electric high-speed centrifugal air (EHSCA) compressors are smaller, and the operating points are closer to the surge condition. When surge occurs, sound is the most direct and convenient signal to be received. In order to quantify the acoustic characteristics of the compressor during surge, this paper combines experiments and simulations to study and analyze the acoustic characteristics of surge of EHSCA compressors. There are high-pressure sound frequency bands distributed near the impeller blade passing frequency BPF, BPF×2, the diffuser’s BPF, and the diffuser BPF×1.5. During surge, the high sound pressure frequency bands spread out, forming a wide-band noise. There is intense turbulence at the top gap of the impeller and the leading edge of the diffuser vanes, which results in extremely loud noise. Finally, a broadband noise is detected at a frequency of 9.6 kHz, which dose not change. The sound field simulation reveals that the impeller outlet sound frequency is close to 9.6 kHz. This indicates that this high sound pressure frequency band is related to the dynamic and static interference caused by the high-energy fluid at the impeller outlet. This study analyzed the causes of surge formation and characterized the surge acoustic characteristics, (a) for studying the characteristics of surge, and (b) for preventing surge occurrence.