scholarly journals Structure design and performance analysis of aerostatic thrust bearing with compound restrictors

2022 ◽  
Vol 355 ◽  
pp. 03070
Author(s):  
Yuntang Li ◽  
Yueliang Ye ◽  
Ruirui Li ◽  
Pengfeng Wang ◽  
Fangfang Zhang
Keyword(s):  
Porous Material ◽  
Thrust Bearing ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Structure Design ◽  
Orifice Diameter ◽  
Load Carrying ◽  
Flow Field Characteristics ◽  
Static Performance ◽  
And Performance

Aerostatic thrust bearing compensated by multi-orifices and porous material restrictor simultaneously is proposed to improve the static performance of the bearing. Load Carrying Capacity (LCC), stiffness and the flow field characteristics of the bearing are obtained by Computational Fluid Dynamic (CFD) simulation. The influences of supply pressure, orifice number, orifice diameter, orifice distribution, porous material thickness and permeability coefficient on the bearing performance are analysed. It is indicated that LCC and stiffness of the bearing with compound restrictors are much higher than those of the bearing with porous material restrictor or multi-orifice restrictor if gas film thickness is in rational range. The bearing with compound restrictors has better stability than that of the bearing with multi-orifice restrictor. Moreover, the optimum bearing parameters with compound restrictors are given to improving the performance of aerostatic thrust bearing.

Integrated air data sensors

2001 ◽  
Vol 105 (1046) ◽  
pp. 223-229 ◽  
Author(s):  
M. A. Menzies
Keyword(s):  
High Speed ◽  
Fluid Dynamic ◽  
Flow Analysis ◽  
Flight Test ◽  
Pressure Sensing ◽  
Performance Verification ◽  
Static Performance ◽  
And Performance ◽  
Distribution Studies ◽  
Bench Testing

Abstract Avionics Specialties in partnership with Honeywell has developed an integrated air data pressure sensor known as the integrated multi-function probe (IMFP). This continuously flow-aligned pressure-sensing device was developed using a multidisciplinary design approach encompassing computational fluid dynamic, (CFD), flow analysis, and experimentation. The computational investigation was performed using the finite element code, CFDesign, by Blue Ridge Numerics and consisted of pressure distribution studies for varying flows around conical sections. The application and integration of this technology to previously developed flow alignment and pressure transducing products lead to design similarity analysis saving considerable development time. Initial experimentation used to develop and refine the design and analysis consisted of laboratory bench testing, low and high-speed wind tunnel investigations, and subsonic flight-testing. Final performance verification was accomplished through data reduction and analysis of an extensive flight test program using a Lockheed Martin F-16 Fighting Falcon. The analysis, design and performance verification of this innovative pressure-sensing device was investigated for direct comparison to conventional Pitot-static performance with particular emphasis toward military fighter aircraft applications.

Novel Thrust Foil Bearing With Pocket Grooves for Enhanced Static Performance

2021 ◽  
Vol 143 (11) ◽  
Author(s):  
Nguyen LaTray ◽  
Daejong Kim
Keyword(s):  
Film Thickness ◽  
Power Loss ◽  
High Speed ◽  
Thrust Bearing ◽  
Test Results ◽  
Foil Bearing ◽  
Load Carrying ◽  
Low Load ◽  
Static Performance ◽  
Foil Thrust Bearing

Abstract The integration of foil bearing technology into high-speed oil-free machines has been slow in progress, in part, due to the low load-carrying capacity of the foil thrust bearing. It is crucial this issue is addressed through innovative solutions without overcomplicating the bearing design because simplicity is one of the attractive features of the foil bearing. This work presents novel thrust foil bearing with taper-flat configuration and pocket grooves on the bearing top foil as a secondary pressure boosting mechanism. Parametric study of the pocket dimensions on a rigid bearing reveals that the bearing static performance is the most sensitive to the pocket angular span. Further two-dimensional fluid–structure interaction analyses on foil thrust bearing predict a reduction of power loss by 10% with increased average film thickness. Minimum film thickness also increases when the bearing is lightly loaded but it is reduced 20% at the taper-flat transition area under high loading condition. This issue can be overcome by using stiffer bump foil; however, this is not implemented in this work due to other design constraints. Test results at 90,000 rpm and 140,000 rpm show, by adding the pocket groove pattern on the top foil, the power loss is reduced by 16% compared to the traditional taper-flat configuration.

scholarly journals Impeller Optimization in Crossflow Hydraulic Turbines

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 313
Author(s):  
Marco Sinagra ◽  
Calogero Picone ◽  
Costanza Aricò ◽  
Antonio Pantano ◽  
Tullio Tucciarelli ◽  
...  
Keyword(s):  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Structural Safety ◽  
3D Fem ◽  
Good Efficiency ◽  
Standard Material ◽  
Variable Head ◽  
Hydraulic Turbines ◽  
Constructive Simplicity ◽  
Mechanical Optimization

Crossflow turbines represent a valuable choice for energy recovery in aqueducts, due to their constructive simplicity and good efficiency under variable head jump conditions. Several experimental and numerical studies concerning the optimal design of crossflow hydraulic turbines have already been proposed, but all of them assume that structural safety is fully compatible with the sought after geometry. We show first, with reference to a specific study case, that the geometry of the most efficient impeller would lead shortly, using blades with a traditional circular profile made with standard material, to their mechanical failure. A methodology for fully coupled fluid dynamic and mechanical optimization of the blade cross-section is then proposed. The methodology assumes a linear variation of the curvature of the blade external surface, along with an iterative use of two-dimensional (2D) computational fluid dynamic (CFD) and 3D structural finite element method (FEM) simulations. The proposed methodology was applied to the design of a power recovery system (PRS) turbine already installed in an operating water transport network and was finally validated with a fully 3D CFD simulation coupled with a 3D FEM structural analysis of the entire impeller.

scholarly journals Computational fluid dynamics (CFD) simulation analysis on retinal gas cover rates using computational eye models

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Makoto Gozawa ◽  
Yoshihiro Takamura ◽  
Tomoe Aoki ◽  
Kentaro Iwasaki ◽  
Masaru Inatani
Keyword(s):  
Cfd Simulation ◽  
Simulation Analysis ◽  
Fluid Dynamic ◽  
Fluid Analysis ◽  
Intraocular Gas ◽  
Pars Plana ◽  
Computational Fluid Dynamics Cfd ◽  
Multiple Breaks ◽  
Gas Volume ◽  
Wall Wettability

AbstractWe investigated the change in the retinal gas cover rates due to intraocular gas volume and positions using computational eye models and demonstrated the appropriate position after pars plana vitrectomy (PPV) with gas tamponade for rhegmatogenous retinal detachments (RRDs). Computational fluid dynamic (CFD) software was used to calculate the retinal wall wettability of a computational pseudophakic eye models using fluid analysis. The model utilized different gas volumes from 10 to 90%, in increments of 10% to the vitreous cavity in the supine, sitting, lateral, prone with closed eyes, and prone positions. Then, the gas cover rates of the retina were measured in each quadrant. When breaks are limited to the inferior retina anterior to the equator or multiple breaks are observed in two or more quadrants anterior to the equator, supine position maintained 100% gas cover rates in all breaks for the longest duration compared with other positions. When breaks are limited to either superior, nasal, or temporal retina, sitting, lower temporal, and lower nasal position were maintained at 100% gas cover rates for the longest duration, respectively. Our results may contribute to better surgical outcomes of RRDs and a reduction in the duration of the postoperative prone position.

scholarly journals Coupled Fluid–Solid Numerical Simulation for Flow Field Characteristics and Supporting Performance of Flexible Support Cylindrical Gas Film Seal

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 97
Author(s):  
Junfeng Sun ◽  
Meihong Liu ◽  
Zhen Xu ◽  
Taohong Liao ◽  
Xiangping Hu ◽  
...  
Keyword(s):  
Flow Field ◽  
Film Thickness ◽  
Fluid Dynamic ◽  
Structural Characteristics ◽  
Structural Parameters ◽  
Equivalent Stress ◽  
Three Dimensional ◽  
High Rotational Speed ◽  
Flexible Support ◽  
Flow Field Characteristics

A new type of cylindrical gas film seal (CGFS) with a flexible support is proposed according to the working characteristics of the fluid dynamic seal in high-rotational-speed fluid machinery, such as aero-engines and centrifuges. Compared with the CGFS without a flexible support, the CGFS with flexible support presents stronger radial floating characteristics since it absorbs vibration and reduces thermal deformation of the rotor system. Combined with the structural characteristics of a film seal, an analytical model of CGFS with a flexible wave foil is established. Based on the fluid-structure coupling analysis method, the three-dimensional flow field of a straight-groove CGFS model is simulated to study the effects of operating and structural parameters on the steady-state characteristics and the effects of gas film thickness, eccentricity, and the number of wave foils on the equivalent stress of the flexible support. Simulation results show that the film stiffness increases significantly when the depth of groove increases. When the gas film thickness increases, the average equivalent stress of the flexible support first decreases and then stabilizes. Furthermore, the number of wave foils affects the average foils thickness. Therefore, when selecting the number of wave foils, the support stiffness and buffer capacity should be considered simultaneously.

scholarly journals Optimal Design and Performance Analysis of Radial MR Valve with Single Excitation Coil

Actuators ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 34
Author(s):  
Guoliang Hu ◽  
Feng Zhou ◽  
Lifan Yu
Keyword(s):  
Pressure Drop ◽  
Magnetic Flux ◽  
Internal Structure ◽  
Total Pressure ◽  
Damping Force ◽  
Flux Lines ◽  
Total Pressure Drop ◽  
Excitation Coil ◽  
Static Performance ◽  
And Performance

The main issue addressed in this paper involves the magnetorheological (MR) valve increasing the pressure drop by changing the internal structure, which leads to the increase of dimension sizes and the easy blocking of the internal channel. Optimizing the design of the traditional radial MR valve without changing the internal structure and whole dimension size is indispensable. Firstly, a radial MR valve with single excitation coil was proposed. The mathematical models of the field-dependent pressure drop and viscosity pressure drop in fluid flow channels were deduced, and the calculation formula of pressure drop was also established. Then, ANSYS software was used to simulate and analyze the distributions of the magnetic flux lines and magnetic flux densities of the proposed radial MR valve. Subsequently, the radial MR valve was simulated and analyzed by using the ANSYS first-order and zero-order simulation tools. In addition, the experimental test bench of the proposed MR valve was setup, the static performance of pressure drop was tested, and the change of pressure drop of the optimal radial MR valve under different loads was studied, furthermore, the response time with current of the initial and optimal radial MR valve were also investigated. Finally, the dynamic performances of the optimal radial MR valve controlled cylinder system under different currents, frequencies and amplitudes were tested, respectively. The experimental results indicate that the total pressure drop of the initial valve is 1.842 MPa when the applied current is 1.8 A, and the total pressure drop of the optimal valve is 2.58 MPa, the increase is 40.07%. Meanwhile, the maximum damping force of the optimal radial MR valve controlled cylinder system can reach about 3.6 kN at the current of 1.25 A, which shows a better optimization effect of the optimal radial MR valve.

scholarly journals Simulation of Hydraulic Cylinder Cushioning

2021 ◽  
Vol 13 (2) ◽  
pp. 494
Author(s):  
Antonio Algar ◽  
Javier Freire ◽  
Robert Castilla ◽  
Esteban Codina
Keyword(s):  
Dynamic Model ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Computational Fluid Dynamic Simulation ◽  
Hydraulic Cylinder ◽  
Outlet Port ◽  
Optimal Behavior ◽  
Radial Movement ◽  
Mechanical Shocks ◽  
Radial Gap

The internal cushioning systems of hydraulic linear actuators avoid mechanical shocks at the end of their stroke. The design where the piston with perimeter grooves regulates the flow by standing in front of the outlet port has been investigated. First, a bond graph dynamic model has been developed, including the flow throughout the internal cushion design, characterized in detail by computational fluid-dynamic simulation. Following this, the radial movement of the piston and the fluid-dynamic coefficients, experimentally validated, are integrated into the dynamic model. The registered radial movement is in coherence with the significant drag force estimated in the CFD simulation, generated by the flow through the grooves, where the laminar flow regime predominates. Ultimately, the model aims to predict the behavior of the cushioning during the movement of the arm of an excavator. The analytical model developed predicts the performance of the cushioning system, in coherence with empirical results. There is an optimal behavior, highly influenced by the mechanical stress conditions of the system, subject to a compromise between an increasing section of the grooves and an optimization of the radial gap.

On the Significance of the Inlet Pressure Build-Up in the Design of Tilting-Pad Bearings

1990 ◽  
Vol 112 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Cz. M. Rodkiewicz ◽  
K. W. Kim ◽  
J. S. Kennedy
Keyword(s):  
Thrust Bearing ◽  
Ambient Pressure ◽  
Inlet Pressure ◽  
Load Carrying Capacity ◽  
Integral Theorem ◽  
Lubricating Film ◽  
Tilting Pad ◽  
Load Carrying ◽  
Momentum Integral ◽  
Entrance Pressure

An operating tilting-pad thrust bearing generates a fore-region which is responsible for maintaining, at the bearing entrance, a pressure which is higher than the ambient pressure. This entrance pressure, in the presented analysis, is obtained by applying to the fore-region the momentum integral theorem. The solution of the lubricating film region is then obtained by using this modified inlet pressure. This solution yields the pressure distribution, the load carrying capacity, the film ratio and the frictional force for several values of the modified Reynolds number and various pivot positions. The analysis shows that there is a significant influence of the fore-region pressure on the bearing performance and that to properly design efficient tilting-pad bearing this effect should be taken into consideration.

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