Fluid Dynamic Forces Acting on the Rotor of a Shaft-Less Miniature Pump

2011 ◽  
Author(s):  
Baotang Zhuang ◽  
Xianwu Luo ◽  
Xin Wang ◽  
Bin Ji ◽  
Hongyuan Xu
Keyword(s):  
Reynolds Equation ◽  
Static Pressure ◽  
Fluid Dynamic ◽  
Thickness Distribution ◽  
Static Pressure Distribution ◽  
Simulation Based ◽  
Social Fields ◽  
Dynamic Forces ◽  
Rotating Impeller ◽  
Fluid Dynamic Bearing

For a miniature pump used in many social fields, it is expected to be able to operate without any shaft and mechanical bearing. Recently, a double-suction shaft-less miniature pump has been developed at the Lab of Multiphase Flow and Biomechanics, Tsinghua University. Because the rotor of the miniature pump is rotating inside the pump casing, a fluid dynamic bearing is necessary to support the pump rotor. In this paper, a fluid dynamic bearing was designed to support the rotating impeller and motor rotor, and was manufactured combined with the miniature pump. In order to evaluate the bearing capability, the numerical simulation based on Reynolds equation was conducted for the fluid dynamic bearing. Both the performance experiment of the pump and the numerical results for the bearing indicate that the fluid dynamic bearing designed for the miniature pump in this study is usable and reliable. It is also noted that the performance including the liquid film thickness distribution, static pressure distribution, bearing capability, etc. of the bearing has been reasonably predicted using the present numerical methods. Further, the bearing capability increased remarkably with eccentric ratio between the bush and journal, and rotational speed of the pump for the fluid dynamic bearing.

Static pressure distribution in the free turbulent jet

1957 ◽  
Vol 3 (1) ◽  
pp. 1-16 ◽  
Author(s):  
David R. Miller ◽  
Edward W. Comings
Keyword(s):  
Static Pressure ◽  
Longitudinal Velocity ◽  
Fluid Motion ◽  
Mean Velocity ◽  
Free Jet ◽  
Static Pressure Distribution ◽  
Two Dimensional Flow ◽  
The Common ◽  
Jet Theory ◽  
Made In

Measurements of mean velocity, turbulent stress and static pressure were made in the mixing region of a jet of air issuing from a slot nozzle into still air. The velocity was low and the two-dimensional flow was effectively incompressible. The results are examined in terms of the unsimplified equations of fluid motion, and comparisons are drawn with the common assumptions and simplifications of free jet theory. Appreciable deviations from isobaric conditions exist and the deviations are closely related to the local turbulent stresses. Negative static pressures were encountered everywhere in the mixing field except in the potential wedge region immediately adjacent to the nozzle. Lateral profiles of mean longitudinal velocity conformed closely to an error curve at all stations further than 7 slot widths from the nozzle mouth. An asymptotic approach to complete self-preservation of the flow was observed.

Fluid dynamic bearing for HD-DVD single-phase spindle motor

2003 ◽  
Author(s):  
Hung-Kuang Hsu ◽  
Chien-Chang Wang ◽  
Mei-Lin Lai ◽  
Yu-Hsiu Chang ◽  
Der-Ray Huang
Keyword(s):  
Single Phase ◽  
Fluid Dynamic ◽  
Spindle Motor ◽  
Fluid Dynamic Bearing

Estimating Bearing Coefficients of Fluid-Dynamic Bearing Spindle Motors: A Theoretical Treatment and Feasibility Study

2011 ◽  
Vol 47 (7) ◽  
pp. 1918-1922 ◽  
Author(s):  
I. Y. Shen ◽  
Erik M. Ladd ◽  
Wei Yang
Keyword(s):  
Feasibility Study ◽  
Fluid Dynamic ◽  
Theoretical Treatment ◽  
Fluid Dynamic Bearing

Ingestion Into the Upstream Wheelspace of an Axial Turbine Stage

1994 ◽  
Vol 116 (2) ◽  
pp. 327-332 ◽  
Author(s):  
T. Green ◽  
A. B. Turner
Keyword(s):  
Pressure Distribution ◽  
Static Pressure ◽  
Three Dimensional ◽  
Computer Code ◽  
Rotor Blades ◽  
Rotor Speed ◽  
Turbine Stage ◽  
Flow Rates ◽  
Static Pressure Distribution ◽  
Axial Clearance

The upstream wheelspace of an axial air turbine stage complete with nozzle guide vanes (NGVs) and rotor blades (430 mm mean diameter) has been tested with the objective of examining the combined effect of NGVs and rotor blades on the level of mainstream ingestion for different seal flow rates. A simple axial clearance seal was used with the rotor spun up to 6650 rpm by drawing air through it from atmospheric pressure with a large centrifugal compressor. The effect of rotational speed was examined for several constant mainstream flow rates by controlling the rotor speed with an air brake. The circumferential variation in hub static pressure was measured at the trailing edge of the NGVs upstream of the seal gap and was found to affect ingestion significantly. The hub static pressure distribution on the rotor blade leading edges was rotor speed dependent and could not be measured in the experiments. The Denton three-dimensional C.F.D. computer code was used to predict the smoothed time-dependent pressure field for the rotor together with the pressure distribution downstream of the NGVs. The level and distribution of mainstream ingestion, and thus the seal effectiveness, was determined from nitrous oxide gas concentration measurements and related to static pressure measurements made throughout the wheelspace. With the axial clearance rim seal close to the rotor the presence of the blades had a complex effect. Rotor blades in connection with NGVs were found to reduce mainstream ingestion seal flow rates significantly, but a small level of ingestion existed even for very high levels of seal flow rate.

scholarly journals Performance Assessment of an Annular S-Shaped Duct

1995 ◽  
Author(s):  
D. W. Bailey ◽  
K. M. Britchford ◽  
J. F. Carrotte ◽  
S. J. Stevens
Keyword(s):  
Shear Stress ◽  
Static Pressure ◽  
Compressor Blade ◽  
Turbine Engines ◽  
Pressure Gradients ◽  
Gas Turbine Engines ◽  
Entry Length ◽  
Static Pressure Distribution ◽  
Flow Curvature ◽  
Inlet Conditions

An experimental investigation has been carried out to determine the aerodynamic performance of an annular S-shaped duct representative of that used to connect the compressor spools of aircraft gas turbine engines. For inlet conditions in which boundary layers are developed along an upstream entry length the static pressure, shear stress and velocity distributions are presented. The data shows that as a result of flow curvature significant streamwise pressure gradients exist within the duct, with this curvature also affecting the generation and suppression of turbulence. The stagnation pressure loss within the duct is also assessed and is consistent with the measured distributions of shear stress. More engine representative conditions are provided by locating a single stage compressor at inlet to the duct. Relative to the naturally developed inlet conditions the flow within the duct is less likely to separate, but mixing out of the compressor blade wakes increases the measured duct loss. With both types of inlet conditions the effect of a radial strut, such as that used for carrying loads and engine services, is also described both in terms of the static pressure distribution along the strut and its contribution to overall loss.

An Investigation of Flow Characteristics and Parameter Effects for a New Concept of Hybrid SVC Nozzle

2018 ◽  
Author(s):  
F. Song ◽  
J. W. Shi ◽  
L. Zhou ◽  
Z. X. Wang ◽  
X. B. Zhang
Keyword(s):  
Static Pressure ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Exhaust System ◽  
Aircraft Engine ◽  
Thrust Coefficient ◽  
Thrust Vectoring ◽  
Static Pressure Distribution ◽  
Thrust Vector ◽  
Vector Angle

Lighter weight, simpler structure, higher vectoring efficiency and faster vector response are recent trends in development of aircraft engine exhaust system. To meet these new challenges, a concept of hybrid SVC nozzle was proposed in this work to achieve thrust vectoring by adopting a rotatable valve and by introducing a secondary flow injection. In this paper, we numerically investigated the flow mechanism of the hybrid SVC nozzle. Nozzle performance (e.g. the thrust vector angle and the thrust coefficient) was studied with consideration of the influence of aerodynamic and geometric parameters, such as the nozzle pressure ratio (NPR), the secondary pressure ratio (SPR) and the deflection angle of the rotatable valve (θ). The numerical results indicate that the introductions of the rotatable valve and the secondary injection induce an asymmetrically distributed static pressure to nozzle internal walls. Such static pressure distribution generates a side force on the primary flow, thereby achieving thrust vectoring. Both the thrust vector angle and vectoring efficiency can be enhanced by reducing NPR or by increasing θ. A maximum vector angle of 16.7 ° is attained while NPR is 3 and the corresponding vectoring efficiency is 6.33 °/%. The vector angle first increases and then decreases along with the elevation of SPR, and there exists an optimum value of SPR for maximum thrust vector angle. The effects of θ and SPR on the thrust coefficient were found to be insignificant. The rotatable valve can be utilized to improve vectoring efficiency and to control the vector angle as expected.

Evaluation of fluid dynamic bearing spindle by vibration base

2005 ◽  
Author(s):  
M. Miwa ◽  
H. Miyazaki ◽  
R. Kaneko ◽  
H. Unozawa
Keyword(s):  
Fluid Dynamic ◽  
Fluid Dynamic Bearing

Geometric Modeling of a Propeller Turbine Runner Using ANSYS BladeGen, Meshing Using ANSYS TurboGrid and Fluid Dynamic Simulation Using ANSYS Fluent

2016 ◽  
Vol 842 ◽  
pp. 164-177 ◽  
Author(s):  
Indra Djodikusumo ◽  
I. Nengah Diasta ◽  
Iwan Sanjaya Awaluddin
Keyword(s):  
Geometric Modeling ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Thickness Distribution ◽  
Ansys Fluent ◽  
Implementation Phase ◽  
Runner Blade ◽  
Modeling Process ◽  
Turbine Runner ◽  
Preparation Phase

This paper aims to demonstrate how to model, mesh and simulate a hydraulic propeller turbine runner based on the geometrical specification of the runner blade. Modeling process is divided into preparation and implementation phase. Preparation phase illustrates how to develop stream surfaces and passages, how to create and transform meanline and how to create an rtzt file. The profile in rtzt file has a certain fix thickness which has to be altered later. Implementation phase describes operations necessary in creating a propeller runner model in ANSYS BladeGen which consist of importing rtzt file, modifying the trailing edge properties and altering profile thickness distribution to that of 4 digits NACA airfoil standard. Grid is generated in ANSYS TurboGrid utilizing ATM Optimized topology. CFD simulation is done using the ANSYS Fluent with pressure inlet and pressure outlet boundary conditions and k-ε turbulence model. Hydraulic efficiency of the runner is calculated utilizing Turbo Topology module in ANSYS Fluent. The authors will share the advantages that may be obtained by using ANSYS BladeGen compared with the use of general CAD Systems.

scholarly journals An Assessment of Quantitative Predictions of Deterministic Mixed Lubrication Solvers

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Yuechang Wang ◽  
Abdel Dorgham ◽  
Ying Liu ◽  
Chun Wang ◽  
Mark C. T. Wilson ◽  
...  
Keyword(s):  
Reynolds Equation ◽  
Thickness Distribution ◽  
Computation Time ◽  
Simulation Method ◽  
Coefficient Matrix ◽  
Mixed Lubrication ◽  
Contact Ratio ◽  
Lubricated Contacts ◽  
Discretization Schemes ◽  
Parametric Studies

Abstract The ability to simulate mixed lubrication problems has greatly improved, especially in concentrated lubricated contacts. A mixed lubrication simulation method was developed by utilizing the semi-system approach which has been proven to be highly useful for improving stability and robustness of mixed lubrication simulations. Then different variants of the model were developed by varying the discretization schemes used to treat the Couette flow terms in the Reynolds equation, varying the evaluation of density derivatives and varying the contribution of terms in the coefficient matrix. The resulting pressure distribution, film thickness distribution, lambda ratio, contact ratio, and the computation time were compared and found to be strongly influenced by the choice of solution scheme. This indicates that the output from mixed lubrication solvers can be readily used for qualitative and parametric studies, but care should be taken when making quantitative predictions.

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