The Effect of Track-Seeking Motion on Off-Track Vibrations of the Head Gimbal Assembly in HDDs

2017 ◽  
Author(s):  
Guoqing Zhang ◽  
Hui Li ◽  
Shengnan Shen ◽  
Tan Trinh ◽  
Frank E. Talke ◽  
...  
Keyword(s):  
Fluid Dynamic ◽  
Angular Acceleration ◽  
Sinusoidal Wave ◽  
Interaction Method ◽  
Square Wave ◽  
Structure Interaction ◽  
Head Gimbal Assembly ◽  
Head Positioning ◽  
Mesh Method ◽  
Simulation Results

The effect of track-seeking on off-track residual vibrations of the head-gimbal assembly (HGA) is investigated for air and helium environments using the so-called “fluid dynamic mesh” method and the “fluid-structure interaction” method. Three different angular acceleration profiles (square wave, triangular wave and sinusoidal wave) are investigated as a function of seek time (10 ms and 5 ms). Results show that smoothening of sharp transitions of the seek profile improves the performance of off-track residual vibrations during track-following and shortens the track-following time of the head positioning servo system. In addition, the effect of lateral flow (windage) on off-track residual vibrations during track-following must be considered for a square wave angular acceleration profile. Simulation results show that helium improves the track-following accuracy compared to air due to the lower windage forces acting on the HGA. We observe that the sinusoidal wave angular acceleration performs best among the three angular acceleration profiles investigated. Furthermore, seek time is found to have only a small effect on off-track residual vibrations during track-following.

Investigation on the function of double tipping bucket for improvement of rainfall measurement

2020 ◽  
Author(s):  
Cai Zhao ◽  
Liu Jiufu ◽  
Liu Hongwei ◽  
Liao Aimin ◽  
Liao Minhan
Keyword(s):  
Rainfall Intensity ◽  
Fluid Model ◽  
Fluid Dynamic ◽  
Systematic Errors ◽  
Rain Gauge ◽  
Water Volume ◽  
Dynamic Simulations ◽  
Mesh Method ◽  
Volume Of Fluid Model ◽  
Simulation Results

<p>The double-tipping bucket rain gauge (SL3-1) is widely used in meteorological stations to minimize the systematic errors by the influence of rainfall intensity on TBRs in China. With two tipping buckets, the upper tipping bucket turns over and injects rainwater into the converging funnel, and the lower tipping bucket can record the rainfall. In this study, CFD (computational fluid dynamic) simulations and experiments were performed to investigate the function of the double tipping bucket for TBRs in different rainfall intensity. In simulation, the volume-of-fluid model and Reynolds-averaged Navier–Stokes realizable k-ε model and dynamic mesh method were used. In experiments, electric balances, with accuracy of 0.001 g, were used to determine the water volume of the upper tipping bucket outflow. It shows that, with a converging funnel, natural precipitation is uniformed at a certain intensity around 1.9mm/min to control the rainwater outflow into blow tipping bucket to measure rainfall and reduce systematic errors caused by different precipitation intensities. Experimental results demonstrate that the outflow curve of the upper tipping bucket has high correspond with simulation results in tipping process. These results can provide knowledge of advantages of double tipping bucket rain gauge in rainfall measurement and improve the structure designs of double tipping bucket for TBRs and obtain more accurate rainfall data.</p>

Strength Analysis of Dual-Chamber Hydrodynamic Coupling Based on One Way FSI

2010 ◽  
Vol 34-35 ◽  
pp. 105-110
Author(s):  
De Sheng Zhang ◽  
Ji Yun Zhao ◽  
Zhan Xu ◽  
Zhen Xing Wang
Keyword(s):  
Maximum Stress ◽  
Working Fluid ◽  
Strength Analysis ◽  
Analysis Software ◽  
Interaction Method ◽  
Dual Chamber ◽  
Element Analysis ◽  
Structure Interaction ◽  
Hydrodynamic Coupling ◽  
Simulation Results

In order to improve the accuracy of stress analysis of blade wheels, one way Fluid- Structure Interaction method was introduced based on the comparisons of existing methods. Finite element analysis software ANSYS along with CFD software FLUENT were comprehensively used for the strength analysis of dual-chamber couplings. According to the simulation results from CFD, the node loads at the interface of pump wheel and the working fluid were obtained and the torque and axial force were predicated. Then the static stress of pump wheel was analyzed with ANSYS. The detail processes were described in this paper. The results show that the blades of pump wheel is loaded by alternating forces, and the maximum stress, which is 64MPa, locates at the junction area of the blades and shell. And the coupling analyzed in this study meets the strength requirement.

scholarly journals Research on the Rapid Closing Jet Mechanism of Pistol Shrimp’s Claws Based on Fluid Dynamic Grid

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Wei Wei ◽  
Xinyu Quan ◽  
Hongchao Cao ◽  
Shijie Zhang ◽  
Ximing Zhao ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Kinetic Energy ◽  
Angular Velocity ◽  
Theoretical Basis ◽  
Fluid Dynamic ◽  
Angular Acceleration ◽  
Hydrodynamic Characteristics ◽  
Fluid Models ◽  
The World ◽  
Simulation Results

The predation behavior of the pistol shrimp is extremely special, and the predation process will produce a huge popping sound, which has caused extensive research by scholars from all over the world. This article carried out a study on the rapid closing jet mechanism of pistol shrimp’s claws. A theoretical model, based on the hydrodynamic characteristics of seawater and the theory of fluid-structure coupling, was proposed for the interaction between the claws and seawater. A simulation model was established using the finite volume software Fluent, and the rapid closing jet mechanism of pistol shrimp’s claws was verified by using fluid dynamic grid. This article studied the influence of different fluid models on the simulation results. The effects of the claws’ closing angular velocity and angular acceleration on the interaction between the claws and seawater were analyzed, which provides a theoretical basis for the development of new underwater kinetic energy weapons.

Thermo-Fluid-Dynamic Design of Reciprocating Compressor Cylinders by Fluid Structure Interaction (FSI)

2011 ◽  
Author(s):  
Riccardo Traversari ◽  
Alessandro Rossi ◽  
Marco Faretra
Keyword(s):  
High Speed ◽  
Fluid Dynamic ◽  
Fluid Structure Interaction ◽  
Classical Equation ◽  
Flow Coefficient ◽  
Reciprocating Compressor ◽  
Complex Situation ◽  
Fluid Structure ◽  
Associated Gas ◽  
Structure Interaction

Pressure losses at the cylinder valves of reciprocating compressors are generally calculated by the classical equation of the flow through an orifice, with flow coefficient determined in steady conditions. Rotational speed has increased in the last decade to reduce compressor physical dimensions, weight and cost. Cylinder valves and associated gas passages became then more and more critical, as they determine specific consumption and throughput. An advanced approach, based on the new Fluid Structure Interaction (FSI) software, which allows to deal simultaneously with thermodynamic, motion and deformation phenomena, was utilized to simulate the complex situation that occurs in a reciprocating compressor cylinder during the motion of the piston. In particular, the pressure loss through valves, ducts and manifolds was investigated. A 3D CFD Model, simulating a cylinder with suction and discharge valves, was developed and experimentally validated. The analysis was performed in transient and turbulent condition, with compressible fluid, utilizing a deformable mesh. The 3D domain simulating the compression chamber was considered variable with the law of motion of the piston and the valve rings mobile according to the fluid dynamic forces acting on them. This procedure is particularly useful for an accurate valve loss evaluation in case of high speed compressors and heavy gases. Also very high pressure cylinders, including LDPE applications, where the ducts are very small and MW close to the water one, can benefit from the new method.

scholarly journals The gas flow pattern through small size Resistive Plate Chambers with 2 mm gap

2021 ◽  
Vol 16 (11) ◽  
pp. P11022
Author(s):  
Y. Pezeshkian ◽  
A. Kiyoumarsioskouei ◽  
M. Ahmadpouri ◽  
G. Ghorbani
Keyword(s):  
Gas Flow ◽  
Fluid Dynamic ◽  
Gas Flow Rate ◽  
Argon Gas ◽  
Dynamic Methods ◽  
Gas System ◽  
Gas Molecules ◽  
Simulation Results ◽  
Resistive Plate Chambers ◽  
The Difference

Abstract A prototype of a single-gap glass Resistive Plate Chamber (RPC) is constructed by the authors. To find the requirements for better operation of the detector's gas system, we have simulated the flow of the Argon gas through the detector by using computational fluid dynamic methods. Simulations show that the pressure inside the chamber linearly depends on the gas flow rate and the chamber's output hose length. The simulation results were compatible with experiments. We have found that the pressure-driven speed of the gas molecules is two orders of magnitude larger in the inlet and outlet regions than the blocked corners of a 14 × 14 cm2 chamber, and most likely the difference in speed is higher for larger detectors and different geometries.

Strength Analysis of Vessel Based on the Fluid Structure Interaction Method

2012 ◽  
Vol 594-597 ◽  
pp. 869-875
Author(s):  
Chao Liu ◽  
Fan Chun Li ◽  
Yajie Yun
Keyword(s):  
Surface Pressure ◽  
Model Transformation ◽  
Optimization Design ◽  
Structure Optimization ◽  
Strength Analysis ◽  
Interaction Method ◽  
Structure Interaction ◽  
Wave Channel ◽  
Calculation Process ◽  
Stress And Deformation

Building a whole vessel model ,and make use of FLUENT to calculate the resistance and surface pressure of the vessel in a certain speed . Compile a user-defined function, in which the numerical wave channel has been developed, thus the surface pressure was calculated in two kinds of special conditions, hogging and sagging, and then by using of the Fluid-solid coupling method, the surface pressure was exported to ANSYS.The method uses a same hull model in the flow field and the structure calculation process, avoiding the loss and distortion of information in the previous model transformation , and the calculated results can analyze more accurately the stress and deformation of the hull. The results for performance assessment of the vessel are effective and the calculation method can be a reference in the structure optimization design of vessels.

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