Research on the fluctuation of the velocity and pressure of the flow field of an aerostatic bearing with a multi-hole integrated restrictor

2021 ◽  
pp. 135065012098525
Author(s):  
Zhiwei Lu ◽  
Junan Zhang ◽  
Bo Liu
Keyword(s):  
Flow Field ◽  
Film Flow ◽  
Three Dimensional ◽  
Simulation Method ◽  
Critical Ratio ◽  
Aerostatic Bearing ◽  
Navier Stokes Equation ◽  
Supply Pressure ◽  
Aerostatic Bearings ◽  
Gas Supply

For an aerostatic bearing with a multi-hole integrated restrictor, which achieved superior precision lubrication-bearing performance, the fluctuations of the velocity and the pressure of the flow field were investigated. In this paper, the large-eddy simulation method was used to solve the three-dimensional Navier–Stokes equation in the calculation area of the gas film flow field at the orifice outlet of an aerostatic bearing, while the overrelaxation iteration method was used to solve the Reynolds equation in the remaining calculation areas. The influence factors of the flow field, such as the diameter of the orifice, the gas supply pressure and the gas film clearance, were derived and discussed. The results showed that the diameter of the orifice and the gas film clearance of aerostatic bearings with a multi-hole integrated restrictor strongly affected the film flow field near the outlet of the restrictor under a specified gas supply pressure. There was a critical ratio between the gas film clearance and the diameter of the orifice of aerostatic bearings with a multi-hole integrated restrictor, which may be an initial signal and an important parameter of the flow field transition from laminar flow to turbulent flow.

scholarly journals Study on the Gas Film Flow Field and its Influencing Factors at the Outlet of the Orifice of the Aerostatic Bearing

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Zhi-Wei Lu ◽  
Jun-An Zhang ◽  
Bo Liu
Keyword(s):  
Flow Field ◽  
Influencing Factors ◽  
Film Flow ◽  
Simulation Method ◽  
Transition To Turbulence ◽  
Orifice Diameter ◽  
Critical Ratio ◽  
Aerostatic Bearing ◽  
Sharp Drop ◽  
Film Pressure

In order to further explore and study the influencing factors and regulars of the gas film flow field at the outlet of the orifice of the aerostatic bearing, the large eddy simulation method was used to calculate the N-S equation in the calculation area of the gas film flow field at the outlet of the orifice of the aerostatic bearing, and the overrelaxation iteration method was used to solve the Reynolds equation in the other calculation areas, which was proposed in this paper. Based on the physical model of the outlet of the orifice of the aerostatic bearing, the solution area of the gas film flow field of the aerostatic bearing was solved, and the calculation results were analyzed and discussed. The results showed that there was a sharp drop of the gas film pressure at the outlet of the orifice of the aerostatic bearing and the separation of the gas film pressure p became inconsistent in the thickness direction of gas film clearance h. It was assumed that there was a critical ratio θ between the gas film clearance h and the orifice diameter d of the aerostatic bearing, and when the ratio of gas film clearance h to the orifice diameter d was greater than the critical ratio θ, various fluctuations of the gas film flow field began to appear, which may be the initial signal state of the gas film flow field of the aerostatic bearing starting to transition to turbulence. It provided a theoretical basis and guidance for further study of the transition lubrication mechanism between the laminar and the turbulent flow at the outlet of the orifice of the aerostatic bearing in this paper.

Characteristics evaluation of gas film in the aerostatic thrust bearing within rarefied effect

2016 ◽  
Vol 231 (2) ◽  
pp. 149-157 ◽  
Author(s):  
Dongju Chen ◽  
Shuai Zhou ◽  
Jihong Han ◽  
Jinwei Fan ◽  
Qiang Cheng
Keyword(s):  
Machine Tool ◽  
Reynolds Equation ◽  
Thrust Bearing ◽  
Film Flow ◽  
Machining Accuracy ◽  
Aerostatic Bearing ◽  
Supply Pressure ◽  
Slip Regime ◽  
Key Factor ◽  
Gas Supply

The characteristic of gas film is a key factor in the performance of the aerostatic bearing. Because the gas film flow is in the slip regime, influence of the rarefied effect is significant. The modified Reynolds equation suitable for compressible gas in the rarefied effect is deduced through introducing the flow factor in the rarefied effect to the Reynolds equation. Pressure distribution, capacity, and stiffness of the gas film under the rarefied effect are analyzed. With the increase of gas pressure, the gas film capacity and stiffness of bearing would also increase. However, the greater the gas supply pressure, the more intense the gas film vibration, so it was important to select a reasonable gas supply pressure for achieving the optimal gas film characteristic. Finally, the gas rarefied effect is verified by the experiment indirectly, which agreed well with the analytical results and provided a theoretical guidance for the machining accuracy of the machine tool.

scholarly journals The Flow Field Analysis and Flow Calculation of Ultrasonic Flowmeter Based on the Fluent Software

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Ling Guo ◽  
Yue Sun ◽  
Ling Liu ◽  
Zhixi Shen ◽  
Ruizhen Gao ◽  
...  
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Simulation Method ◽  
Ultrasonic Flowmeter ◽  
Field Analysis ◽  
Dimensional Structure ◽  
Power Correction ◽  
Ideal Condition ◽  
Proposed Model ◽  
Fluent Software

We can build the three-dimensional structure model based on the Gambit software and achieve the distribution of flow field in the pipe and reflux flow condition at the position of transducer in regard to the real position of transducer according to the Fluent software. Under the framework, define the reflux length based on the distance of reflux along the channel and evaluate the effect of reflux on flow field. Then we can correct the power factor with the transmission speed difference method in the ideal condition and obtain the matching expression of power correction factor according to the practice model. In the end, analyze the simulation experience and produce the sample table based on the proposed model. The comparative analysis of test results and simulation results demonstrates the validity and feasibility of the proposed simulation method. The research in this paper will lay a foundation for further study on the optimization of ultrasonic flowmeter, enhance the measurement precision, and extend the application of engineering.

Effects of Bowed Stators on a Transonic Fan With Distorted Inlet

2008 ◽  
Author(s):  
Peng Sun ◽  
Ji’ang Han ◽  
Jingjun Zhong ◽  
Liquan Tao ◽  
Muxiao Yang ◽  
...  
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Navier Stokes ◽  
3D Analysis ◽  
Navier Stokes Equation ◽  
Design Point ◽  
Fan Performance ◽  
Flow Loss ◽  
Transonic Fan ◽  
Software Pack

The adverse impacts of inlet distortion on fan/compressor have been recognized as an important problem for several decades, and it is still a topic of considerable interest. Many research works indicate that it is possible to improve the performance and stability of a fan in clean and distorted inlet flow by using bowed stator blades. But, how bowed stator influences the flow field and what kind of bow patterns and angles can improve fan performance better are still not clearly studied. Therefore, a 3D analysis in fan flow field with different bowed stator blades is required. In this paper, a time-dependent three-dimensional Reynolds averaged Navier-Stokes equation composed in “Fluent Software Pack” is carried out in a parallel supercomputer. The fan with straight/different bowed stators is simulated with a clean/distorted inlet boundary condition to obtain a better understanding of bowed stators effects in distorted flow field. The analysis of results consists of three aspects. The first is about the effects of straight/bowed stators on the fan characteristics with clean and distorted inlet. Bowed stators can improve the fan performance significantly when inlet is distorted, especially at design point. But, when inlet is clean bowed stators even worsen the fan performance at design point. The effects of bowed stators on the fan performance at design point are analyzed secondly. It is found that different bow angles have different influence on rotor or stator flow field. Small bow angle stator reduces the flow loss in rotor but have no effect on stator flow field. Large bow angle stator can reduce the flow loss in stator markedly, but increases the rotor loss. Finally the patterns of flow loss caused by total pressure distortion with straight and different bowed stators are compared and analyzed in detail. The scale of vortex in stator is weakened by large bow angle blades significantly, which decreased the stator loss.

Effect of Reefs Spacing on Flow Field Around Artificial Reef Based on the Hydrogen Bubble Experiment

2017 ◽  
Author(s):  
Yanli Tang ◽  
Xiangyu Long ◽  
Xinxin Wang ◽  
Fenfang Zhao ◽  
Liuyi Huang
Keyword(s):  
Numerical Model ◽  
Flow Field ◽  
Size Structure ◽  
Three Dimensional ◽  
Artificial Reef ◽  
Ocean Current ◽  
Water Tank ◽  
Hydrogen Bubble ◽  
Navier Stokes Equation ◽  
Spacing Distance

When an ocean current encounters a vertical structure, such as an artificial reef (AR), it can create a plankton-rich upwelling that provides a reliable feeding spot for fish. The fish attracted into the AR zones depends largely on the size, structure, and layout of the ARs. Thus, this study was conducted to demonstrate the effect of different layouts on the flow field around cubic ARs, a common type of AR in China. Water tank tests and numerical simulations were used to study the flow field around the cubic ARs. Experiment of hydrogen bubble was conducted in a water tank to observe the effect of the reef spacing on the flow field around the reefs. Using computational fluid dynamics, a three-dimensional numerical model was established based on the Navier-Stokes equation. The standard k-ϵ model was adopted to simulate the flow field around the ARs. On comparing the streamlines of the flow field around the ARs, it was found that the numerical results were in good agreement with the hydrogen bubble results. Using the numerical model, the flow around the ARs with different transverse or longitudinal spacing was simulated. When the transverse spacing distance is equal to the width of the AR, the upwelling becomes stronger. When the distance increases to 7L, the interaction between the reefs can be ignored. When the longitudinal spacing distance is equal to 1L, the effect of the interaction of the reefs on the back eddy is quite significant. However, as the distance increases, the interaction between two reefs gradually weakens.

scholarly journals Research on 3D Simulation Method of Nearshore Storm Surge Based on FLIP

2021 ◽  
Vol 2074 (1) ◽  
pp. 012007
Author(s):  
Qiuyan Wang ◽  
Hao Du
Keyword(s):  
Flow Field ◽  
Storm Surge ◽  
Three Dimensional ◽  
Simulation Method ◽  
Environmental Engineering ◽  
Ocean Engineering ◽  
Special Effects ◽  
Fluid State ◽  
Wide Range ◽  
Application Prospects

Abstract This paper proposes a FLIP-based three-dimensional storm surge simulation method. Based on the Fluid Implicit Particle (FLIP) method, the flow field is calculated by FLIP fluid, and finally through the standard coloring based on PBR in the Unity engine. The device renders the fluid state model generated at each moment. The experimental results show that the method in this paper not only meets the realistic requirements of nearshore storm surge simulation, but also effectively improves the efficiency of scene rendering. The result can be used not only in game production and movie special effects, but also in engineering simulations such as ocean engineering and environmental engineering, and has a wide range of application prospects and application values.

Numerical research on inlet total pressure distortion in a transonic compressor with non-axisymmetric stator

2017 ◽  
Vol 233 (2) ◽  
pp. 667-678 ◽  
Author(s):  
Peng Sun ◽  
Wenguang Fu ◽  
Hong Wang ◽  
Jingjun Zhong
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Deep Understanding ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Transonic Compressor ◽  
Compressor Performance ◽  
Software Pack

The adverse impacts of non-uniform inlet flow have been the focus for several decades with the increase of the operating range of engines. A deep understanding of the flow mechanism of distortion passing through a compressor is needed urgently and the improvement of the compressor performance becomes more and more important. In this paper, a non-axisymmetric stator is presented with significant non-axisymmetric characteristics in a transonic compressor to investigate compressor performance and flow field effects. A time-dependent three-dimensional Reynolds-averaged Navier-Stokes equation composed in ‘Fluent Software Pack’ is validated and used to perform the simulations. The flow fields with distorted inlet are obtained and the effects of original stator and non-axisymmetric stator in a transonic compressor are compared. The results are discussed in terms of the effects of non-axisymmetric stator on compressor performance, blockage of flow passage, rotor and stator. The results show that the non-axisymmetric stator influences not only the stator flow field but also the rotor flow field, so the efficiency and total pressure ratio are improved correspondingly.

Simulation of the Flow Parameters of the Multi-Microchannel Aerostatic Restrictor

2012 ◽  
Vol 241-244 ◽  
pp. 1278-1284
Author(s):  
Yu Bing Zhang ◽  
Cai Qin Li ◽  
Dong Sheng Li
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Film Thickness ◽  
Three Dimensional ◽  
Simulation Method ◽  
Gas Pressure ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Flow Parameters ◽  
Numerical Simulation Method

A numerical simulation method, FLUENT,has been selected to simulate the flow field parameters of the multi-microchannel aerostatic restrictor. Pressure, temperature and velocity distributions of the restrictor under different gas film thickness and gas pressure were got and compared. Used Pro / E to establish three-dimensional model of restrictor and imported it into GAMBIT for meshing, and then used FLUENT for simulation.

Effects of Bowed Stator on a Fan Characteristic With Distorted Inlet

2010 ◽  
Author(s):  
Peng Sun ◽  
Jingjun Zhong ◽  
Muxiao Yang ◽  
Shaobing Han
Keyword(s):  
Flow Field ◽  
Research Work ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Stall Margin ◽  
Design Point ◽  
Fan Performance ◽  
Flow Loss

The adverse impacts of inlet distortion on fan/compressor have been recognized as an important problem for several decades. But it is still a topic of considerable interest. Prior work has proved, in distorted flow field, bowed stators can constrain separation and reduce flow loss. Different bow patterns and angles influence the fan/compressor in different way. But the above work was carried out only at the design point. How bowed stators influence the fan/compressor performance and stability at other operating conditions is still not clearly studied. Therefore, a deeper research work is required. In this paper, a time-dependent three-dimensional Reynolds averaged Navier-Stokes equation composed in “Fluent Software Pack” is carried out in a parallel supercomputer. A fan with straight/30° bowed stators is simulated with a clean/distorted inlet boundary condition at different operating conditions to obtain the fan characteristic. Two main aspects are contained in this paper. The first is about the effects of straight/bowed stators on the fan characteristics with clean and distorted inlet at different operating point. It is found that 30° bowed stator will worsen the fan performance at most operating conditions with clean inlet. But, when inlet is distorted, it can improve the fan performance and increase the stall margin obviously. The effects of bowed stators on the fan performance and flow field at near stall and design point are analyzed secondly. The fan stability and the anti-distortion capability can be improved by using bowed stator when the inlet total pressure is non-uniform.

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