Effect of operating parameters of a magnetically controlled spiral capsule robot on its performance

Robotica ◽  
2021 ◽  
pp. 1-12
Author(s):  
Liang Liang ◽  
Puhua Tang ◽  
Yu Liu ◽  
Yan Xu
Keyword(s):  
Pipe Wall ◽  
Fluid Pressure ◽  
Forward Direction ◽  
Turbulent Intensity ◽  
Operating Parameters ◽  
Numerical Result ◽  
Fluid Field ◽  
Image Velocimetry ◽  
Field Velocity ◽  
Capsule Robot

Abstract A magnetically controlled spiral capsule robot is designed. When the robot is running in a pipe filled with mucus, computational fluid dynamics is used to analyze the fluid field (velocity, streamlines, and vorticity) in the pipe, and particle image velocimetry is used to measure the above fluid field surrounding the robot. The measured fluid field is basically similar to the numerical result. The relationship between the operating parameters of the robot and the performance of the robot is further calculated and analyzed. The results show that the resistance to the robot in the forward direction, average turbulent intensity of the fluid surrounding the robot, and maximum fluid pressure to the pipe wall are proportional to the robotic translational speed. The resisting moment of the robot in the forward direction, average turbulent intensity of the fluid surrounding the robot, and maximum fluid pressure to the pipe wall are proportional to the robotic rotational speed.

Scaling effects in spiral capsule robots

2017 ◽  
Vol 231 (4) ◽  
pp. 307-314 ◽  
Author(s):  
Liang Liang ◽  
Rong Hu ◽  
Bai Chen ◽  
Yong Tang ◽  
Yan Xu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Vessels ◽  
Driving Force ◽  
Pipe Wall ◽  
Fluid Pressure ◽  
Turbulent Intensity ◽  
Load Torque ◽  
Capsule Robot ◽  
Dynamics Method

Spiral capsule robots can be applied to human gastrointestinal tracts and blood vessels. Because of significant variations in the sizes of the inner diameters of the intestines as well as blood vessels, this research has been unable to meet the requirements for medical applications. By applying the fluid dynamic equations, using the computational fluid dynamics method, to a robot axial length ranging from 10−5 to 10−2 m, the operational performance indicators (axial driving force, load torque, and maximum fluid pressure on the pipe wall) of the spiral capsule robot and the fluid turbulent intensity around the robot spiral surfaces was numerically calculated in a straight rigid pipe filled with fluid. The reasonableness and validity of the calculation method adopted in this study were verified by the consistency of the calculated values by the computational fluid dynamics method and the experimental values from a relevant literature. The results show that the greater the fluid turbulent intensity, the greater the impact of the fluid turbulence on the driving performance of the spiral capsule robot and the higher the energy consumption of the robot. For the same level of size of the robot, the axial driving force, the load torque, and the maximum fluid pressure on the pipe wall of the outer spiral robot were larger than those of the inner spiral robot. For different requirements of the operating environment, we can choose a certain kind of spiral capsule robot. This study provides a theoretical foundation for spiral capsule robots.

Optimization of a columnar vortex generator installed over an aircraft carrier ski-jump ramp

2019 ◽  
Vol 234 (1) ◽  
pp. 223-230
Author(s):  
Rafael Bardera
Keyword(s):  
Vortex Generator ◽  
Wind Tunnel Testing ◽  
Low Velocity ◽  
Aircraft Carrier ◽  
Recirculation Bubble ◽  
Columnar Vortex ◽  
Flow Disturbances ◽  
Image Velocimetry ◽  
Field Velocity ◽  
Flight Deck

Aircraft performances over aircraft carriers are essential in modern navies. Take-off operation is critical due to the short runway available. The ski-jump ramp is a useful system that allows to operate under safe conditions. However, the sharp edge at the end of the runway provokes a region with recirculation bubble and low velocity producing strong flow disturbances. Hence, the aircraft performances are affected and the pilot’s workload is augmented. Previous researches showed that columnar vortex generator reduces the recirculation bubble generated over the end of flight deck. This article presents an in-depth experimental study performed by wind tunnel testing in order to determine the relation between the columnar vortex generator size and the recirculation bubble reduction. Particle image velocimetry is used to investigate the flow field velocity and flow structure around the ski-jump ramp as a non-intrusive experimental technique. Encouraging results were found for the biggest columnar vortex generator studied.

An Experimental Study on the Performance of Drag-Reducing Polymers in Single- and Multiphase Horizontal Flow Using Particle Image Velocimetry

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Ihab H. Alsurakji ◽  
A. Al-Sarkhi ◽  
M. Habib ◽  
Hassan M. Badr
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Pipe Wall ◽  
Fluid Dynamic ◽  
Water Soluble ◽  
Experimental Investigations ◽  
Two Phase ◽  
Image Velocimetry ◽  
Flow Field Characteristics ◽  
Phase Water

This paper presents experimental investigations conducted to understand the influence of water-soluble drag-reducing polymers (DRPs) in single- and two-phase (stratified wavy) flow on flow-field characteristics. These experiments have been presented for water and air–water flowing in a horizontal polyvinyl chloride 22.5-mm ID, 8.33-m long pipe. The effects of liquid flow rates and DRP concentrations on streamlines and the instantaneous velocity were investigated by using particle image velocimetry (PIV) technique. A comparison of the PIV results was performed by comparing them with the computational results obtained by fluent software. One of the comparisons has been done between the PIV results, where a turbulent flow with DRP was examined, and the laminar–computational fluid dynamic (CFD) prediction. An agreement was found in the region near the pipe wall in some cases. The results showed the powerfulness of using the PIV techniques in understanding the mechanism of DRP in single- and two-phase flow especially at the regions near the pipe wall and near the phases interface. The results of this study indicate that an increase in DRP concentrations results in an increase in drag reduction up to 45% in single-phase water flow and up to 42% in air–water stratified flow.

Experimental Performance of a Swirl-Venturi Fuel Mixer for a Fuel Cell Reformer

2006 ◽  
Author(s):  
Robert Tacina ◽  
Yolanda R. Hicks ◽  
Robert Anderson ◽  
Randy J. Locke ◽  
Heidi N. Robinson ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Power Plants ◽  
Capillary Tube ◽  
Chemical Species ◽  
Venturi Tube ◽  
Fuel Injector ◽  
Flow Measurements ◽  
Swirl Angle ◽  
Image Velocimetry ◽  
Field Velocity

The objective of this work is to develop a liquid fuel injector-mixer to provide a uniform mixture of vaporized fuel, steam and air to a fuel cell reformer. This effort supports the NASA fuel cell program, which has the goal of cleaner aerospace power plants. The demonstration project is sized for a 10 kW fuel cell. The Swirl Venturi Mixer (SVM) is the fuel injector-mixer concept explored in the present study. The SVM consists of: a capillary tube to inject the fuel; a venturi tube to maximize the effective air-assist atomization of fuel injected at the throat; and a controlled expansion of radial mixing at the diffuser portion of the venturi. A swirler upstream of the venturi tube enhances turbulent mixing and improves the diffuser performance by suppressing flow separation. Variables evaluated are: swirl angle, throat diameter, throat length and diffuser length. The test section has a 76 mm diameter and includes a quartz cylinder to allow laser-based flow measurements downstream of the injector. Raman spectroscopy is used to measure chemical species distribution across the flow field while particle image velocimetry (PIV) is used to determine the field velocity profile. Test conditions consisted of an inlet air temperature of 700K, inlet steam temperature of 480K, atmospheric pressure, Jet A fuel, and mixture velocities of 1 to 3 m/s.

Damping Force Analysis of Magnetorheological (MR) Dampers

2012 ◽  
Vol 187 ◽  
pp. 311-314
Author(s):  
Hai Jun Xing
Keyword(s):  
Pressure Gradient ◽  
Fluid Pressure ◽  
Algebraic Expression ◽  
Force Analysis ◽  
Damping Force ◽  
Mr Fluid ◽  
Mr Dampers ◽  
Numerical Result ◽  
Force Velocity

In this paper, utilizing Herschel-Bulkley model, the equation of MR fluid pressure gradient is derived in order to predict MR damper’s force-velocity behavior. The equation, showing as a complicated nonlinear algebraic expression including various parameters, is then simplified to a nondimensional equation. This is followed by the analysis of the root of this nondimensional equation and an approximate root closely corresponding to numerical result is given.

A method to estimate the transient fluid pressure of a piezoelectric inkjet printer using system dynamic analysis

2017 ◽  
Vol 23 (6) ◽  
pp. 1130-1135
Author(s):  
Kun Wang ◽  
Juntong Xi
Keyword(s):  
Boundary Condition ◽  
Transfer Function ◽  
Numerical Models ◽  
Fluid Pressure ◽  
Helmholtz Resonator ◽  
Coupling Model ◽  
Transient Pressure ◽  
Content Type ◽  
Fluid Field ◽  
Inkjet Printer

Purpose This paper aims to present a method based on dynamics to find the transient pressure at the nozzle area of a piezoelectric inkjet printer. This pressure responds to input signals of the piezoelectric driver deformation. The pressure at the nozzle is the boundary condition of the computational fluid dynamics model of the inkjet printer nozzle, and serves as the “bridge” between the piezoelectric driver actuation and the droplet generation of an inkjet printer. Design/methodology/approach The transient pressure was estimated using a fluid-solid coupling numerical model of the printerhead. In this study, a simple step-shape signal was applied. The printerhead chamber was considered to act as a linear Helmholtz resonator to determine the system transfer function between the input of driver deformation and the output of pressure. By decomposing the input signal into several simple signals, the transient pressure is the superposition of those calculated pressures. Findings The pressure values determined by transfer function and by superposition match the pressure values directly calculated by a fluid-solid coupling model. This demonstrates the rationality and practicability of the method. Originality/value This paper proposes a method to identify a proper boundary condition of pressure for numerical models that only include the fluid field around the nozzle. This strategy eliminates the need to calculate the complex and unstable fluid-solid coupling for every pattern of input. Additionally, the suitable boundary condition of transient pressure can be set rather than relying on the shape of the PZT driver deformation signal.

scholarly journals Quantitative Visualisation of Compressible Flows

2018 ◽  
Vol 2018 (1) ◽  
pp. 137-145
Author(s):  
Wit Stryczniewicz
Keyword(s):  
Transonic Flow ◽  
Compressible Flows ◽  
Flow Visualisation ◽  
Image Velocimetry ◽  
Boundary Layer Interaction ◽  
Field Velocity ◽  
Induced Flow ◽  
Transonic And Supersonic Flows ◽  
Quantitative Flow

Abstract The paper demonstrates the feasibility of quantitative flow visualisation methods for investigation of transonic and supersonic flows. Two methods and their application for retrieving compressible flow field properties has been described: Background Oriented Schlieren (BOS) and Particle Image Velocimetry (PIV). Recently introduced BOS technique extends the capabilities of classical Schlieren technique by use of digital image processing and allow to measure density gradients field. In the presented paper a review of applications of BOS technique has been presented. The PIV is well established technique for whole field velocity measurements. This paper presents application of PIV for determination of the shock wave position above airfoil in transonic flow regime. The study showed that application of quantitative flow visualisation techniques allows to gain new insights on the complex phenomenon of supersonic and transonic flow over airfoils like shock-boundary layer interaction and shock induced flow separation.

Characterizing the Effects of G-Loading in an Ultra Compact Combustor via Sectional Models

2010 ◽  
Author(s):  
Kenneth D. LeBay ◽  
Aaron C. Drenth ◽  
Levi M. Thomas ◽  
Marc D. Polanka ◽  
Richard D. Branam ◽  
...  
Keyword(s):  
Combustion Process ◽  
Velocity Fields ◽  
Main Flow ◽  
Turbulent Intensity ◽  
Radial Acceleration ◽  
Reduced Chemistry ◽  
Image Velocimetry ◽  
Planar Laser ◽  
Combustion Optimization ◽  
Small Engines

The Ultra Compact Combustor (UCC) has shown viable merit for significantly improving gas turbine combustor performance. This concept combines a trapped-vortex approach with a circumferential cavity utilizing buoyancy and high g-loading to improve efficiency and reduce combustor size. Models for small engines can provide g-loading up to 4,000 g’s. However, as the scale of the combustor increases, the g-loading will necessarily decrease. Thus, the importance of understanding the effect of g-loading is pivotal to the applicability of this design to larger engine diameters. The Air Force Institute of Technology’s Combustion Optimization and Analysis Laser (COAL) laboratory studied this effect with sectional models of the UCC. By using both straight and curved sections of the radial cavity, the g-loading can be varied from 0–15,000 g’s. Particle Image Velocimetry (PIV) was used for velocity fields and turbulence statistics. Two-line Planar Laser-Induced Fluorescence (PLIF) of the hydroxyl (OH) radical was used for 2-D temperature profiles. Single-line PLIF was also used for flame location where OH concentrations were too low for temperature determination. Several cases were studied with varying both the equivalence ratio and the main/cavity mass flow ratio. Through the synthesis of velocity fields, temperature and flame location PLIF data, the effect of g-loading was accurately characterized. The immense radial acceleration acts to significantly increase the turbulent intensity present in the combusting regions. This increased turbulent intensity resulted in increased mixing and subsequently a significantly increased flame speed causing a reduced chemistry time. Because the chemistry time was reduced, there was less OH present in the main flow for the high g-load cases due to the combustion process being significantly further progressed when the cavity flow mixes with the main flow.

scholarly journals Flow field velocity measurement of liquid interaction with rigid and flexible wall

2019 ◽  
Vol 213 ◽  
pp. 02031
Author(s):  
Darina Jasikova ◽  
Michal Kotek ◽  
Frantisek Pochyly ◽  
Vaclav Kopecky
Keyword(s):  
Particle Image ◽  
Glass Tube ◽  
Newtonian Liquid ◽  
Pulse Period ◽  
Membrane Pump ◽  
Image Velocimetry ◽  
Particle Image Velocimetry Method ◽  
Flow Interactions ◽  
Flexible Wall ◽  
Field Velocity

The motivation of this research was to determine the flow interactions on the pulsation and to express the influence on the flow character in the rigid and flexible tube. The character of Newtonian liquid was measured with the Particle Image Velocimetry method (PIV). Here, we used glass tube and Tygon tube for our comparison. We build the circuit equipped with membrane pump for generating pulsatile flow. The results were analysed over the pulse period sampled in 10 time steps. The fluid flow varied from Re 560 to Re 8800. The velocity profiles uncovered backward revers flows closed to the wall. These structures are prevailing close to flexible wall. The effect of interaction between pulsatile liquid flow and flexible wall was experimentally proved.

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