scholarly journals Continuous Phase Measurement in the W7-X Infrared Interferometer by Means of a FPGA and High-Speed ADCs

2010 ◽  
Vol 58 (3) ◽  
pp. 771-777 ◽  
Author(s):  
L. Esteban ◽  
M. Sánchez ◽  
J. Sánchez ◽  
P. Kornejew ◽  
M. Hirsch ◽  
...  
Keyword(s):  
High Speed ◽  
Phase Measurement ◽  
Continuous Phase

scholarly journals Modeling the Excess Velocity of Low-Viscous Taylor Droplets in Square Microchannels

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 162 ◽  
Author(s):  
Thorben Helmers ◽  
Philip Kemper ◽  
Jorg Thöming ◽  
Ulrich Mießner
Keyword(s):  
High Speed ◽  
Process Intensification ◽  
Continuous Phase ◽  
Channel Cross Section ◽  
Optimization Approach ◽  
Mean Flow ◽  
Bypass Flow ◽  
Wall Film ◽  
Proposed Model ◽  
The Mean

Microscopic multiphase flows have gained broad interest due to their capability to transfer processes into new operational windows and achieving significant process intensification. However, the hydrodynamic behavior of Taylor droplets is not yet entirely understood. In this work, we introduce a model to determine the excess velocity of Taylor droplets in square microchannels. This velocity difference between the droplet and the total superficial velocity of the flow has a direct influence on the droplet residence time and is linked to the pressure drop. Since the droplet does not occupy the entire channel cross-section, it enables the continuous phase to bypass the droplet through the corners. A consideration of the continuity equation generally relates the excess velocity to the mean flow velocity. We base the quantification of the bypass flow on a correlation for the droplet cap deformation from its static shape. The cap deformation reveals the forces of the flowing liquids exerted onto the interface and allows estimating the local driving pressure gradient for the bypass flow. The characterizing parameters are identified as the bypass length, the wall film thickness, the viscosity ratio between both phases and the C a number. The proposed model is adapted with a stochastic, metaheuristic optimization approach based on genetic algorithms. In addition, our model was successfully verified with high-speed camera measurements and published empirical data.

Numerical Simulation and Analysis of Effect of Injection Volume on Biomass Particle Cyclone Venturi Dryer

2021 ◽  
Author(s):  
Guohai Jia ◽  
Guoshuai Tian ◽  
Zicheng Gao ◽  
Dan Huang ◽  
Wei Li ◽  
...  
Keyword(s):  
High Speed ◽  
Optimization Design ◽  
Gas Flow ◽  
Continuous Phase ◽  
Temperature Fields ◽  
Maximum Pressure ◽  
Two Phase ◽  
Velocity Change ◽  
Injection Volume ◽  
Wood Debris

Abstract Cyclone venturi dryer is suitable for drying materials with large particle size and wide distribution. The working process of cyclone venturi dryer is a very complicated three-dimensional and turbulent motion, so it is difficult to be studied theoretically and experimentally. In order to study the internal flow characteristics of the biomass particle cyclone venturi dryer, the computational fluid dynamics (CFD) software was used to simulate the gas-solid two-phase flow field inside the cyclone venturi dryer. The continuous phase adopts the Realizable k-ε turbulence model and the particle phase is discrete. The effects of different injection volume on the pressure, velocity, and temperature fields inside a cyclone venturi dryer were analyzed. The results showed that the maximum pressure drop and velocity change inside the dryer were at the venturi pipe. The wet material of the cyclone venturi dryer was inhaled into the venturi contraction tube by the negative pressure formed after the highspeed airflow was ejected, thus the mixture was completed in the venturi throat. The wood debris material was mixed with the high-speed hot gas flow in the venturi throat and then sprayed into the diffusion pipe. In the diffusion pipe of venturi, the heat and mass transfer process of wet wood debris and heat flow in venturi diffusion tube was completed. It is in good agreement with the simulation results. This study can provide a reference for the optimization design of the related cyclone venturi dryer structure.

Stroboscopic Online Phase Measurement Profilometry for High-Speed Rotating Objects

2019 ◽  
Vol 39 (8) ◽  
pp. 0812003
Author(s):  
种晴 Chong Qing ◽  
曹益平 ◽  
陈雨婷 Chen Yuting
Keyword(s):  
High Speed ◽  
Phase Measurement ◽  
Rotating Objects

Impingement of an unsteady two-phase jet on unheated and heated flat plates

1993 ◽  
Vol 252 ◽  
pp. 499-523 ◽  
Author(s):  
İ. Bedii Özdemir ◽  
J. H. Whitelaw
Keyword(s):  
Wall Temperature ◽  
High Speed ◽  
Continuous Phase ◽  
Size Class ◽  
Wall Jet ◽  
Flat Plates ◽  
Two Phase ◽  
Secondary Atomization ◽  
Wall Jet Flow ◽  
The Impact

This paper is concerned with an experimental investigation of the oblique impingement of an unsteady, axisymmetric two-phase jet on heated surfaces. Size and velocity were measured simultaneously with a phase-Doppler velocimeter, and the spatial distributions over the wall jet were found to be correlated with the interfacial activities as inferred from vertical velocity measurements in the vicinity of the wall. These results are discussed together with size measurements by a laser-diffraction technique to quantify the effect of the approach conditions of the inflowing jet droplet field and wall temperature in relation to mechanisms of secondary atomization.Two mechanisms of secondary atomization were identified; the first did not involve direct wall contact and was due to the strain acting on the droplets by the continuous phase within the impingement region and was enhanced by thermal effects from the wall to cause breakup. The approaching velocity of the inflowing droplets to the plate was important to this process so that higher velocities increased the rate of strain within the impingement region and, consequently, the wall temperature promoting the secondary atomization shifted towards lower values. The second mechanism required direct wall contact and involved atomization of the film deposited on the wall by the impingement of the inflowing two-phase jet. With the penetration of high-speed inflowing droplets into the film, liquid mass was raised into the two-phase medium due to splashes from the film so that a new size class with larger droplets was generated. The resulting large droplets tended to stay close to the wall within the impingement region with small vertical velocitiesIn between the injections, the suspended droplet field above the film oscillated normal to the plate as a cloud so that the impact of large droplets on the film resulted in coalescence with the film and the ejection of smaller numbers of small droplets. The unsteady wall jet flow, caused by the arrival of the spray at the plate, swept the vertically oscillating droplet cloud radially outwards so that the resulting radial transport caused the dynamics of the unsteady film to be correlated with the size characteristics of the unsteady wall jet. Based on this phenomenological description, a radial droplet transport equation is derived.The correlation suggests that the secondary atomization with direct wall contact is the dominant process for the generation of a new size class within the wall flow and initiates the mutual interaction between the unsteady film and wall jet droplet field.

A Fully Digital Beam Position and Phase Measurement Electronics for the Proton LINAC in ADS

2013 ◽  
Vol 333-335 ◽  
pp. 379-388 ◽  
Author(s):  
Xiao Fang Hu ◽  
Lei Zhao ◽  
Xing Shun Gao ◽  
Shu Bin Liu ◽  
Qi An
Keyword(s):  
High Resolution ◽  
High Speed ◽  
Dynamic Range ◽  
Phase Measurement ◽  
Sampling Technique ◽  
Critical System ◽  
Beam Position ◽  
Under Sampling ◽  
Better Than ◽  
Proton Linac

The beam measurement is essential for an accelerator. In the proton LINAC in China Accelerator Driven Sub-critical system (ADS), a high resolution measurement of beam position and phase is required within one single system. To meet the requirement, this beam position and phase measurement (BPPM) electronics is designed based on a direct RF under-sampling technique, which simplifies both the analog and digital processing circuits. The signals received from the LINAC are narrow pulses with a repetition frequency of 162.5 MHz and a dynamic range more than 40 dB. After analog manipulation, the input RF signals are directly converted to In-phase and Quadrature-phase (IQ) streams through under-sampling based on the high-speed high-resolution Analog-to-Digital conversion technique. All signal processing is integrated in one single FPGA, in which real-time beam position, phase and current can be obtained. A series of simulations and tests have been conducted to evaluate the performance. Initial test results indicate that this system achieves a position resolution better than 20 um and a phase resolution better than 0.1 degree over a 40 dB dynamic range with the bandwidth of 780 kHz, which is well beyond the application requirements.

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