Pneumatic Lines Research Articles

Process Tomographic Measurements of Granular Flow in a Pneumatic Conveying System

The application of process tomography (PT) technologies, i.e. Electrostatic Tomography (EST) and Electrical Capacitance Tomography (ECT) to investigate complex industrial processes has obtained wide popularity in recent years. This study focuses on the characterization of non-uniformly distributed electrostatic effects across the cross-section of a pneumatic transportpipe. A digital electrometer was used to measure the electrostatics current and an ECT was used to observe the particle distribution in a vertical pipe. Due to non-uniform particle-wall collisions, the electrostatics generated was observed to be non-uniformly distributed across the pipe cross-section, especially at pipe bends and in a vertical pipe. Large electrostatic effects were associated with high particle concentration in the pipe. There was a good correspondence between the electrostatic effects measured and particle concentration distributions obtained using ECT. Based on ECT measurements at the vertical pipe section, it was observed that particles tended to concentrate at sections where generation of electrostatic charges was high. Thus, it is clear that electrostatic effects should be the key factor giving rise to non-uniform particle concentration distribution in pneumatic transport lines.

Automated Systems.

Automated Systems.

Design and Control of a 1-DOF MRI Compatible Pneumatically Actuated Robot with Long Transmission Lines.

This paper presents the design and control of an MRI-compatible 1-DOF needle driver robot and its precise position control using pneumatic actuation with long transmission lines. MRI provides superior image quality compared to other imaging modalities such as CT or ultrasound, but imposes severe limitations on the material and actuator choice (to prevent image distortion) due to its strong magnetic field. We are primarily interested in developing a pneumatically actuated breast biopsy robot with a large force bandwidth and precise targeting capability during radio-frequency ablation (RFA) of breast tumor, and exploring the possibility of using long pneumatic transmission lines from outside the MRI room to the device in the magnet to prevent any image distortion whatsoever. This paper presents a model of the entire pneumatic system. The pneumatic lines are approximated by a first order system with time delay, because its dynamics are governed by the telegraph equation with varying coefficients and boundary conditions, which cannot be solved precisely. The slow response of long pneumatic lines and valve subsystems make position control challenging. This is further compounded by the presence of non-uniform friction in the device. Sliding mode control (SMC) was adopted, where friction was treated as an uncertainty term to drive the system onto the sliding surface. Three different controllers were designed, developed, and evaluated to achieve precise position control of the RFA probe. Experimental results revealed that all SMCs gave satisfactory performance with long transmission lines. We also performed several experiments with a 3-DOF fiber-optic force sensor attached to the needle driver to evaluate the performance of the device in the MRI under continuous imaging.

Modelling an electropneumatic brake system for commercial vehicles

The safety of vehicles on roadways depends, among other things, on a properly operating brake system. Commercial vehicles such as trucks and buses are equipped with an air brake system that uses compressed air as the energy-transmitting medium. The brake response time is a critical parameter that affects the stopping distance of a vehicle. The existing air brake system in a commercial vehicle has mechanically operated valves and pneumatic hoses that are used to transfer the compressed air from the storage reservoir to the foundation brake. Replacing the mechanical valves with electronically operated regulators and reducing the pneumatic lines will potentially reduce the brake response time thereby providing a reduced stopping distance. This study focuses on the development and mathematical modelling of an electropneumatic brake system for commercial vehicles. A mathematical model that correlates the pressure transients in the brake chamber to the voltage input provided to the electropneumatic brake has been developed. The efficacy of this model is tested by comparing its results with experimental data for various test runs. This mathematical model will be used towards model-based control and fault diagnosis of the electropneumatic brake.

다리를 이용한 클램핑 방식의 자벌레 이동방식 대장내시경로봇

본 논문은 자벌레 이동장치의 전, 후반부에 각각 여섯 개의 다리로 이루어진 고정장치를 사용하여 인체내에서 원활하게 이동할 수 있는 대장내시경로봇을 제안하였다. 또한, 관탐사용 이동장치로 기 개발된 하나의 공압선을 이용한 자벌레 이동방식을 적용하여 공압선과 이동환경 사이의 마찰을 줄여주어 이동 성능을 높여주었다. 이동 성능을 평가하기 위하여 로봇을 직경 15㎜, 길이 110~250㎜ 의 크기로 설계 및 제작 후, 아크릴 관과 죽은 돼지의 창자에서 이동실험을 수행하였다. 실험을 통하여 로봇은 곡관의 반경이 25㎜ 이상이면 이동이 가능함을 알 수 있었고, 직관의 경우 수평관에서 33㎜/s, 수직관에서 12.1㎜/s 의 이동 속도를 보여주었다. 결론적으로 하나의 공압선을 이용하여 구동되고 양단에 다리로 구성된 고정장치를 장착한 제안된 로봇은 대장내시경 로봇으로써 신뢰성이 높은 이동성능을 보여주었다.

타이어 시뮬레이터를 이용한 능동형 타이어 공기압 제어 시스템 개발

This study was performed to develop an active tire pressure control system that can adjust tire pressure to the optimum level according to traveling and working condition of agricultural tractor. For the development of active tire pressure control system, pneumatic supplier, solenoid valve block including pneumatic supply line, infinite rotation type pneumatic supplier with rotary joint unit, tire pressure transceiver module and control algorithm were developed. Also, tire simulator was developed. Using this tire simulator, the feasibility of each part constructing actual system was tested by checking the performance. The average communication success ratio was 98.3% between tire pressure transmitter and receiver module according to the various tire rotational speed and data receipt position of receiver module. The communication performance of the developed transmitter and receiver module was very stable in any condition. The tire pressure control system was accomplished by using the proportional control algorithm in this study. Also tire pressure control performance of developed control system was analyzed by using the tire simulator. As a result of control performance analysis to the developed system, the developed control system took 307 seconds to inflate agricultural tractor's tire from 50 kPa to 180 kPa. In opposite case, it took 210 seconds. Also it was able to control the tire pressure accurately under <TEX>${\pm}0.9%$</TEX> (FS) in any condition.

Perfused multiwell plate for 3D liver tissue engineering

In vitro models that capture the complexity of in vivo tissue and organ behaviors in a scalable and easy-to-use format are desirable for drug discovery. To address this, we have developed a bioreactor that fosters maintenance of 3D tissue cultures under constant perfusion and we have integrated multiple bioreactors into an array in a multiwell plate format. All bioreactors are fluidically isolated from each other. Each bioreactor in the array contains a scaffold that supports formation of hundreds of 3D microscale tissue units. The tissue units are perfused with cell culture medium circulated within the bioreactor by integrated pneumatic diaphragm micropumps. Electronic controls for the pumps are kept outside the incubator and connected to the perfused multiwell by pneumatic lines. The docking design and open-well bioreactor layout make handling perfused multiwell plates similar to using standard multiwell tissue culture plates. A model of oxygen consumption and transport in the circulating culture medium was used to predict appropriate operating parameters for primary liver cultures. Oxygen concentrations at key locations in the system were then measured as a function of flow rate and time after initiation of culture to determine oxygen consumption rates. After seven days of culture, tissue formed from cells seeded in the perfused multiwell reactor remained functionally viable as assessed by immunostaining for hepatocyte and liver sinusoidal endothelial cell (LSEC) phenotypic markers.

English

The microballoon actuators are used for the active flow control in turbulent boundary layer for aerodynamic control of flight vehicles. The packaging, interfacing, and integration of the microballoon actuators within the flight vehicle play a key role for functioning of the microballoon actuators during the flight conditions. This paper addresses the design and analysis of packaging and integration aspects and associated issues. The use of microballoon actuators on the control surfaces and nose cone of flight vehicles has the positive influence of delaying the flow separation from the aerodynamic surface. This results in enhancing aerodynamic effectiveness and lift as well as reduction of drag. A typical control surface is configured with eight microballoon actuators symmetric wrt the hinge line of the control surface and embedded within the control surface. Provision of the Pneumatic feed line system for inflation and deflation of the microballoons within the control surface has been made. The nose cone has been designed to have 32 such actuators at the circular periphery. The design is found to be completely feasible for the incorporation of microballoon actuators, both in the nose cone and in the control surface. Defence Science Journal, 2009, 59(5), pp.485-493 , DOI:http://dx.doi.org/10.14429/dsj.59.1549

Microfluidic chip for combinatorial mixing and screening of assays

This paper reports the design, fabrication and validation of a microfluidic well plate for combinatorial screening applications. Each well within the array is comprised of two 200 picoliter compartments that each contain a photonic crystal biosensor to enable the on-chip, in situ detection of (bio-) molecular binding events. This microfluidic chip utilizes arrays of Actuate-to-Open valves to isolate all compartments, which allows the chip to be decoupled from pneumatic control lines and thus to be transported freely between filling, sensing and characterization platforms. A proof-of-principle 4 x 4 protein/antibody binding assay was performed to demonstrate the discrete mixing and on-chip sensing capabilities.

Development of novel two-interconnected fluidized bed system

Two-interconnected fluidized bed systems are widely used in various processes such as Fisher-Tropsch, hot gas desulfurization, CO2 capture-regeneration with dry sorbent, chemical-looping combustion, sorption-enhanced steam methane reforming, chemical-looping hydrogen generation system, and so on. However, conventional two-interconnected fluidized bed systems are very complex, large, and difficult to operate because most of these systems require a riser and/or pneumatic transport line for solid conveying and loopseals or seal-pots for gas sealing, recirculation of solids to the riser, and maintaining of pressure balance. To solve these problems, a novel two-interconnected fluidized bed system has been developed. This system has two bubbling beds, solid injection nozzles, solid conveying lines, and downcomers. In this study, the effects of operating variables on solid circulation rate and gas leakage between two beds have been investigated in a cold mode two-interconnected fluidized bed system. The solid circulation rate increased as the hole diameter on the injection nozzle, the diameter of the injection nozzle, the solid height above the holes, and the number of holes on the injection nozzle increased. The gas leakage between the beds was negligible. Moreover, long-term operation of continuous solid circulation up to 60 hours was performed to check the feasibility of stable operation. The pressure drop profiles in the system loop were maintained steadily and solid circulation was smooth and stable.

One pneumatic line based inchworm-like micro robot for half-inch pipe inspection

By using only one pneumatic line, an inchworm-like micro robot for pipe inspection is invented. Based on drilling different micro holes among the three chambers, the timing of the airflow can be controlled within the chambers. The rear clamp, the elongation module, and the front clamp work sequentially as the air flows into each chamber. It enables the robot not only to generate inchworm-like locomotion, but also to allow for a significant reduction in both the stiffness of pneumatic lines and the friction force caused by one pneumatic line. In addition, it is possible to fabricate a micro robot with diameter of 10 mm since it does not need extra pneumatic lines to connect chambers. In order to operate the robot efficiently, the stroke corresponding to the supplied pressure is theoretically analysed with various sizes of holes between the rear clamp and the elongation module and it is compared to the stroke of the experimental results. Based on these results, maximum velocity was obtained by tuning the air insufflation time under the in-pipe conditions. Finally, the adoptability of the robot was tested under a variation of pipe diameters.

ESTIMATION OF A CRITICAL PRESSURE RATIO OF A PNEUMATIC PIPE-LINE AND ITS SIMULATION

We considered the so-called Fanno flow as a model of flow through pneumatic pipe lines with a constant diameter. The flow is one dimensional, steady and adiabatic. The friction coefficient is constant. We succeeded to express the critical pressure ratio of the flow which is choking at the exit of the pipe line by three parameters, the pipe diameter, the pipe length and the friction coefficient. We compared the theoretically estimated critical pressure ratio to the experimental results. The results showed the good agreements except the case of the short pipe lines less than 10 cm. It was confirmed that our method of determination of the ratio was very useful for the flow calculation using ISO choke equation. With these studies we established the simulation program for the Fanno flow on MATLAB_Simulink and show that the program was easily applied to connected pipelines in series.

A New Efficiency Index for Analysing and Minimizing Energy Consumption in Pneumatic Systems

AbstractIn pneumatic systems the consumption of electrical energy depends almost linearly on the production of compressed air. Hence, the operation of the pneumatic line in any application plant has an enormous effect on the overall energy efficiency. In analysis the compressed air system can be divided into three subsystems: production, after treatment (storage and transmission) and consumption. These systems interact with each other and strongly affect overall system energy requirements. Starting from the dynamical models of the subsystems a new generic energy efficiency index (CA-index) is introduced in the paper. It can be used both in one compressor and multi-compressor systems. The fact that the consumption of compressed air may be either pressure dependent or pressure independent is taken into account in the basic equations and in the energy efficiency index. The maximization of the index is carried out by defining and solving a mathematical optimization problem, which then gives the best possible ...

Simulation, animation and program support for a high performance pneumatic force actuator system

Program support, simulation and the animation of dual action pneumatic actuators controlled with proportional spool valves are developed. Various factors are involved, such as time delay in the pneumatic lines, leakage between chambers, air compressibility in cylinder chambers as well as non-linear flow through the valve. Taking into account the complexity of the model, and the fact that it is described by partial different equations, it is important to develop the program support based on numerical methods for solving this kind of problems. Simulation and program support in Maple and Matlab programming languages are conducted, and the efficiency of the results is shown from the engineering point of view.

Frequency Response Model for Branched Pneumatic Sensing Systems

A frequency response model for branched pneumatic sensors is developed. A typical application is prediction of pneumatic latency and attenuation in aircraft airdata systems, where pneumatic lines are branched to feed a variety of instruments, navigation systems, and pilot displays. The model is developed using small perturbations of the unsteady Navier-Stokes equations. The linearized equations are radially averaged and expressed in the frequency domain. The result is one-dimensional boundary value problem where the pressure oscillation for a given frequency is expressed as a function of position within the sensor. Assuming constant tube geometry and gas properties along an arbitrarily small tubing element allows a closed-form solution of the boundary value equations. This solution becomes a fundamental building block for solving the frequency response of more complex pneumatic geometries. The analysis process employed is similar to applying Kirchhoff's laws to analyze complex electrical circuits. The model predictions are compared against experimental data generated for a simple two-branch configuration. Comparisons for both symmetrical and unbalanced branches are presented. Experiment setup and procedures are described. The comparisons show that the model accurately predicts both the magnitude and phase frequency response of dominant and reflected wave harmonics within each branch of the system.

Preliminary Flight Tests of a Hinge-Less Roll Control Effecter

Introduction T HERE has been a growing research effort to achieve effective hinge-less flight control, spurred on by advances in fluidic control. For purposes of stealth, reduced vehicle weight, increased robustness and damage tolerance as well as compactness, hinge-less methodology is extremely attractive. Hinge-less control can be implemented through either continuous or oscillatory flow manipulation. Continuous manipulation can be achieved using blowing. Past research efforts have shown jet flaps1,2 and circulation control3,4 to be effective at augmenting lift and varying pitching moment. A recent study has shown that a highly deflected (normal to the surface) jet flap can match the performance of a Gurney flap using moderate jet momentum coefficients.5 However, continuous blowing invariably requires drawing air off the engine’s compressor or using shaft power to drive a compressor. Ducting is also required to route the air through its ejection path. Consequently, weight and thrust penalties can be incurred. It would be advantageous to the designer to have the flexibility to employ a modular air-injection system that can be placed locally where control is required. The system can be configured to function as a jet flap or used for augmenting existing control effecters (forming a blown flap). Such a system would have the advantage of not requiring pneumatic lines and can be employed in flight vehicles where a pneumatic source is not present (e.g., unmanned aerial vehicles). In this Note we detail the design and implementation of a self-contained modular blower system. Blower design details are elucidated, as are verification of the blower’s effectiveness as a roll control device through flight testing.

Detection of the breakage of pharmaceutical tablets in pneumatic transport

Pneumatic transport of pharmaceutical tablets is very convenient, compact and greatly reduces contamination. A potential problem, however, is the breakage of a significant fraction of the transported tablets, causing serious product quality problems. Since the flowrate of tablets transported through a given pneumatic transport line increases with gas velocity, lines are often operated at gas velocities slightly below the velocity at which tablets break. Minor changes in operating conditions can have a large effect on the impact resistance of tablets and on the observed tablet breakage rate. Therefore, maintaining a constant gas velocity is not sufficient to keep the tablet breakage rate below an acceptable level. The objective of the present study was to develop a reliable and non-invasive on-line method for the detection of tablet breakage. Pharmaceutical acetaminophen tablets were transported pneumatically in a 0.1 m diameter pipeline consisting of a 5 m vertical and a 4.0 m horizontal section made of either re-enforced PVC or steel. The pipeline flow regime was determined by visual observation through clear pipeline sections. Tablet breakage was quantified by screening tablet samples. Acoustic measurements were recorded at different locations along the pipeline. Analysis of the signals from microphones attached to the wall of the elbow and horizontal section provided a reliable detection of conditions leading to tablet breakage.

Gasdynamic analysis of a pneumatic line launcher

A solution to the problem of motion of a projectile in the bore of a pneumatic line launcher equipped with a fast-acting valve of large clear opening is obtained. The results are represented in the user-friendly graphical form and include a variety of the gasdynamic and design parameters of the launcher that influence the projectile velocity. The calculated data are in good agreement with data of multiparametric experiments.

Electrostatic phenomena in gas-solids fluidized beds

Electrostatic charges are generated by particle-wall, particle-particle and particle-gas contacts in gas-solids transport lines and fluidized bed reactors. High particle charge densities can lead to particle agglomeration, particle segregation, fouling of reactor walls and internals, leading to undesirable by-product and premature shut-down of processing equipment. In this paper, the charge generation, dissipation and segregation mechanisms are examined based on literature data and recent experimental findings in our laboratory. The particle-wall contact charging is found to be the dominant charge generation mechanism for gas-solids pneumatic transport lines, while bipolar charging due to intimate particle-particle contact is believed to be the dominant charge generation mechanism in gas fluidized beds. Such a bipolar charging mechanism is also supported by the segregation patterns of charged particles in fluidized beds in which highly charged particles tend to concentrate in the bubble wake and drift region behind rising bubbles.

A device for aerosol charge measurement and sampling

In this work, a device for aerosol charge measurement and dust sampling is presented. The device is basically an open-ended Faraday pail with a filter to collect the sample. It can be attached to a pneumatic transfer line or it can be used with hose, depending on the situation. When the system was developed, special emphasis was put on the ease of use and reliability. The device can be assembled and disassembled with one twist. The reliability and the operation of the device was tested using two different powder materials, test dust and polystyrene pellets, and four different hose materials. By combining these materials, different extents and polarities of tribo-charge were obtained. The device proved to be easily operated and the test results showed good reproducibility.