Phase discrimination and a high accuracy algorithm for PIV image processing of particle–fluid two-phase flow inside high-speed rotating centrifugal slurry pump

2015 ◽  
Vol 45 ◽  
pp. 93-104 ◽  
Author(s):  
Baocheng Shi ◽  
Jin jia Wei ◽  
Yan Zhang
Keyword(s):  
Image Processing ◽  
High Speed ◽  
Two Phase Flow ◽  
High Accuracy ◽  
Phase Flow ◽  
Two Phase ◽  
Phase Discrimination

High Speed Imaging and Two-Phase Flow Patterns During Flow Boiling in a Single Microchannel

2008 ◽  
Author(s):  
Jacqueline Barber ◽  
Khellil Sefiane ◽  
David Brutin ◽  
Lounes Tadrist
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Pressure Sensors ◽  
Flow Patterns ◽  
Bubble Nucleation ◽  
Phase Flow ◽  
Vapour Bubble ◽  
Two Phase ◽  
Over Time

Boiling in microchannels remains elusive due to the lack of full understanding of the mechanisms involved. A powerful tool in achieving better comprehension of the mechanisms is detailed imaging and analysis of the two phase flow at a fundamental level. We induced boiling in a single microchannel geometry (hydraulic diameter 727 μm), using a refrigerant FC-72, to investigate several flow patterns. A transparent, metallic, conductive deposit has been developed on the exterior of rectangular microchannels, allowing simultaneous uniform heating and visualisation to be conducted. The data presented in this paper is for a particular case with a uniform heat flux of 4.26 kW/m2 applied to the microchannel and inlet liquid mass flowrate, held constant at 1.33×10−5 kg/s. In conjunction with obtaining high-speed images and videos, sensitive pressure sensors are used to record the pressure drop profiles across the microchannel over time. Bubble nucleation, growth and coalescence, as well as periodic slug flow, are observed in the test section. Phenomena are noted, such as the aspect ratio and Reynolds number of a vapour bubble, which are in turn correlated to the associated pressure drops over time. From analysis of our results, images and video sequences with the corresponding physical data obtained, it is possible to follow visually the nucleation and subsequent both ‘free’ and ‘confined’ growth of a vapour bubble over time.

Analysis of Transient Two-Phase Flow in Pressure Safety Valve Outlet Headers

2018 ◽  
Author(s):  
Maral Taghva ◽  
Lars Damkilde
Keyword(s):  
Steady State ◽  
Shock Waves ◽  
High Speed ◽  
Two Phase Flow ◽  
Safety Valve ◽  
Strong Shock ◽  
Flow Property ◽  
Phase Flow ◽  
Transient Pressure ◽  
Two Phase

To protect a pressurized system from overpressure, one of the most established strategies is to install a Pressure Safety Valve (PSV). Therefore, the excess pressure of the system is relieved through a vent pipe when PSV opens. The vent pipe is also called “PSV Outlet Header”. After the process starts, a transient two-phase flow is formed inside the outlet header consisting of high speed pressurized gas interacting with existing static air. The high-speed jet compresses the static air towards the end tail of the pipe until it is discharged to the ambiance and eventually, the steady state is achieved. Here, this transient process is investigated both analytically and numerically using the method of characteristics. Riemann’s solvers and Godunov’s method are utilized to establish the solution. Propagation of shock waves and flow property alterations are clearly demonstrated throughout the simulations. The results show strong shock waves as well as high transient pressure take place inside the outlet header. This is particularly important since it indicates the significance of accounting for shock waves and transient pressure, in contrast to commonly accepted steady state calculations. More precisely, shock waves and transient pressure could lead to failure, if the pipe thickness is chosen only based on conventional steady state calculations.

Calculating Method for the Solid Phase Effect Coefficient of the Solid-Fluid Two Phase Flow Centrifugal Pump

2010 ◽  
Vol 29-32 ◽  
pp. 658-663
Author(s):  
Chuan Jun Li ◽  
Gang Yu ◽  
Xin Wang
Keyword(s):  
Differential Equation ◽  
Centrifugal Pump ◽  
Two Phase Flow ◽  
Solid Phase ◽  
High Accuracy ◽  
Phase Flow ◽  
Phase Effect ◽  
Two Phase ◽  
Error Band ◽  
Calculating Method

In order to acquire the solid-fluid two phase flow centrifugal pump’s slurry head according with the fact, the solid phase effect coefficient must be calculated precisely. By analysising the acting forces on the solid particle, its moving differential equation was established. And the calculating formula of the solid phase effect coefficient was deduced based on the equation. For the sake of verifying its validity, a test of contrast and comparison on the calculating slurry heads by some ways was carried out. The results shows that the relative error values of the slurry head calculated are less than 2.00% with a small and stably error band. The method has the advantage of simple calculating process, high accuracy, low randomness and good practicability.

MEASUREMENT OF INTERFACIAL AREA TRANSPORT OF GAS-LIQUID TWO-PHASE FLOW IN A MINI PIPE USING IMAGE-PROCESSING

2004 ◽  
Vol 2004.9 (0) ◽  
pp. 73-76
Author(s):  
Norihiro Fukamachi ◽  
Tatsuya Hazuku ◽  
Tomoji Takamasa ◽  
Takashi Hibiki ◽  
Mamoru Ishii
Keyword(s):  
Image Processing ◽  
Two Phase Flow ◽  
Interfacial Area ◽  
Phase Flow ◽  
Two Phase ◽  
Interfacial Area Transport

scholarly journals Experimental Investigation of the Performance and Spray Characteristics of a Supersonic Two-Phase Flow Ejector with Different Structures

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1166 ◽  
Author(s):  
Shizhen Li ◽  
Wei Li ◽  
Yanjun Liu ◽  
Chen Ji ◽  
Jingzhi Zhang
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Fire Suppression ◽  
Cone Angle ◽  
Water Mist ◽  
Pulsation Period ◽  
Phase Flow ◽  
Two Phase ◽  
Half Cone ◽  
Half Cone Angle

A two-phase flow ejector is an important part of a water mist fire suppression system, and these devices have become a popular research topic in recent years. This paper proposes a supersonic ejector that aims to improve the efficiency of water mist fire suppression systems. The effects of ejector geometric parameters on the entrainment ratio (ER) were explored. The effects of primary flow pressure (PP) on the mixing process and flow phenomena were studied by a high-speed camera. The experimental results show that the ER first increases and then decreases with increasing PP. ER increases with increasing ejector area ratio (AR). The PP corresponding to the maximum ER of ejectors with a different nozzle exit position (NXP) is 3.6 bar. The ejector with an NXP of +1 and AR of 6 demonstrate the best performance, and the ER of this ejector reaches 36.29. The spray half-cone angle of the ejector increases with increasing ER, reaching a maximum value of 7.07°. The unstable atomization half-cone angle is mainly due to a two-phase flow pulsating phenomenon. The pulsation period is 10 ms. In the present study, a general rule that provides a reference for ejector design and selection was obtained through experiments.

6. Inviscid instability of high speed two-phase flow

1998 ◽  
Vol 1 (1) ◽  
pp. 7-7 ◽  
Author(s):  
G. H. Schnerr ◽  
S. Adam
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Inviscid Instability

Estimation of Average Void Fraction for Gas-Liquid, Two-Phase Flow in an Industrial Nozzle Assembly Using a Quick-Closing-Valve

2008 ◽  
Author(s):  
Mohammad A. Rahman ◽  
Johana Gomez ◽  
Ted Heidrick ◽  
Brian A. Fleck ◽  
Jennifer McMillan
Keyword(s):  
Void Fraction ◽  
High Speed ◽  
Two Phase Flow ◽  
Video Camera ◽  
Synchronization Error ◽  
Phase Flow ◽  
Closing Time ◽  
Two Phase ◽  
Void Fractions ◽  
Atomization Performance

Experimentally accurate void fraction measurements are a challenge in an air/water, two-phase flows through an industrial nozzle assembly, as a highly non-uniform void fraction exists in the feeding conduit prior to the nozzle. In this study, average void fractions were measured by isolating a section in the feeding conduit of a horizontal nozzle assembly, termed as the quick-closing-valve (QCV) technique. A high-speed video camera was utilized to capture the asynchronization closing time, tac. The average closing time and asynchronization for the pneumatically controlled valves were 200 ms and 2 ms, respectively. Based on the equation of 100umtac (1−α)/αlc, the synchronization error between the two valves was 1.12%, 1.26%, and 1.79% for the 1%, 2% and 4% ALR cases, respectively; here um is the mixture velocity, α is the void faction, and lc is the closing length. Higher synchronization error at 4% ALR occurs due to enhanced momentum in the flow regime. Experimental results indicate that the average α over the 33.4 cm feeding conduit (6.25 mm ID) was 76% (αtheoretical = 75%) for the 2% ALR, and 85% (αtheoretical = 83%) for the 3.3% ALR. In the two-phase, two-component flow the α affects the drop size and stability of the spray produced from an industrial nozzle assembly. Learning from this study will yield insights and conceptual understanding of two-phase flow phenomena in conduit, which would affect stability, pulsation tendency, and possibly atomization performance of the nozzle downstream. Two-phase flow nozzles have wide applications in the industries, e.g. petrochemical, pharmaceutical, and others.

Sign in / Sign up

Export Citation Format

Share Document