Lyapunov instability of the stationary flows of polymeric fluid in an infinite plane channel with constant flow rate

2021 ◽  
pp. 125541
Author(s):  
A.M. Blokhin ◽  
D.L. Tkachev ◽  
A.V. Yegitov
Keyword(s):  
Flow Rate ◽  
Plane Channel ◽  
Infinite Plane ◽  
Constant Flow ◽  
Polymeric Fluid ◽  
Constant Flow Rate ◽  
Stationary Flows ◽  
Lyapunov Instability

Pumpless Fuel Supply Using Pressurized Fuel Regulated by Autonomous Flow-Rate Regulation Valves

2012 ◽  
Vol 9 (3) ◽  
Author(s):  
Il Doh ◽  
Young-Ho Cho
Keyword(s):  
Fuel Cells ◽  
Flow Rate ◽  
Electrical Power ◽  
Initial Pressure ◽  
Flow Regulation ◽  
Present System ◽  
Constant Flow ◽  
Constant Flow Rate ◽  
Fuel Supply ◽  
Fuel Flow

A pumpless fuel supply using pressurized fuel with autonomous flow regulation valves is presented. Since micropumps and their control circuitry consume a portion of the electrical power generated in fuel cells, fuel supply without micropumps makes it possible to provide more efficient and inexpensive fuel cells than conventional ones. The flow regulation valves in the present system maintain the constant fuel flow rate from the pressurized fuel chamber even though the fuel pressure decreases. They autonomously adjust fluidic resistance of the channel according to fuel pressure so as to maintain constant flow rate. Compared to previous pumpless fuel supply methods, the present method offers more uniform fuel flow without any fluctuation using a simple structure. The prototypes were fabricated by a polymer micromolding process. In the experimental study using the pressurized deionized water, prototypes with pressure regulation valves showed constant flow rate of 5.38 ± 0.52 μl/s over 80 min and 5.89 ± 0.62 μl/s over 134 min, for the initial pressure in the fuel chamber of 50 and 100 kPa, respectively, while the other prototypes having the same fluidic geometry without flow regulation valves showed higher and gradually decreasing flow rate. The present pumpless fuel supply method providing constant flow rate with autonomous valve operation will be beneficial for the development of next-generation fuel cells.

Exergy analysis of integrated photovoltaic thermal solar water heater under constant flow rate and constant collection temperature modes

2009 ◽  
Vol 86 (12) ◽  
pp. 2592-2597 ◽  
Author(s):  
Arvind Tiwari ◽  
Swapnil Dubey ◽  
G.S. Sandhu ◽  
M.S. Sodha ◽  
S.I. Anwar
Keyword(s):  
Flow Rate ◽  
Exergy Analysis ◽  
Solar Water Heater ◽  
Constant Flow ◽  
Water Heater ◽  
Constant Flow Rate ◽  
Solar Water ◽  
Collection Temperature

scholarly journals Axisymmetric three-dimensional gravity currents generated by lock exchange

2018 ◽  
Vol 851 ◽  
pp. 507-544 ◽  
Author(s):  
Roberto Inghilesi ◽  
Claudia Adduce ◽  
Valentina Lombardi ◽  
Federico Roman ◽  
Vincenzo Armenio
Keyword(s):  
Froude Number ◽  
Flow Rate ◽  
Rapid Development ◽  
Three Dimensional ◽  
Gravity Currents ◽  
Constant Flow ◽  
Axially Symmetric ◽  
Grashof Number ◽  
Constant Flow Rate ◽  
Dimensional Gravity

Unconfined three-dimensional gravity currents generated by lock exchange using a small dividing gate in a sufficiently large tank are investigated by means of large eddy simulations under the Boussinesq approximation, with Grashof numbers varying over five orders of magnitudes. The study shows that, after an initial transient, the flow can be separated into an axisymmetric expansion and a globally translating motion. In particular, the circular frontline spreads like a constant-flow-rate, axially symmetric gravity current about a virtual source translating along the symmetry axis. The flow is characterised by the presence of lobe and cleft instabilities and hydrodynamic shocks. Depending on the Grashof number, the shocks can either be isolated or produced continuously. In the latter case a typical ring structure is visible in the density and velocity fields. The analysis of the frontal spreading of the axisymmetric part of the current indicates the presence of three regimes, namely, a slumping phase, an inertial–buoyancy equilibrium regime and a viscous–buoyancy equilibrium regime. The viscous–buoyancy phase is in good agreement with the model of Huppert (J. Fluid Mech., vol. 121, 1982, pp. 43–58), while the inertial phase is consistent with the experiments of Britter (Atmos. Environ., vol. 13, 1979, pp. 1241–1247), conducted for purely axially symmetric, constant inflow, gravity currents. The adoption of the slumping model of Huppert & Simpson (J. Fluid Mech., vol. 99 (04), 1980, pp. 785–799), which is here extended to the case of constant-flow-rate cylindrical currents, allows reconciling of the different theories about the initial radial spreading in the context of different asymptotic regimes. As expected, the slumping phase is governed by the Froude number at the lock’s gate, whereas the transition to the viscous phase depends on both the Froude number at the gate and the Grashof number. The identification of the inertial–buoyancy regime in the presence of hydrodynamic shocks for this class of flows is important, due to the lack of analytical solutions for the similarity problem in the framework of shallow water theory. This fact has considerably slowed the research on variable-flow-rate axisymmetric gravity currents, as opposed to the rapid development of the knowledge about cylindrical constant-volume and planar gravity currents, despite their own environmental relevance.

Application of Constant Flow Rate Control Valve in Pump Discharge Regulation

2019 ◽  
Vol 145 (7) ◽  
pp. 06019005 ◽  
Author(s):  
Soheil Atashparvar ◽  
Mohammad Bijankhan ◽  
Ali Mahdavi Mazdeh
Keyword(s):  
Flow Rate ◽  
Rate Control ◽  
Control Valve ◽  
Constant Flow ◽  
Constant Flow Rate ◽  
Discharge Regulation ◽  
Flow Rate Control

Effect of Rotating Electromagnetic Field on the Conductivity of Aqueous NaCl Solution

2011 ◽  
Vol 391-392 ◽  
pp. 1080-1084
Author(s):  
Nan Li ◽  
Feng Chai ◽  
Lei Chen ◽  
Shu Kang Cheng
Keyword(s):  
Electromagnetic Field ◽  
Electromagnetic Fields ◽  
Flow Rate ◽  
Constant Flow ◽  
Nacl Solution ◽  
Flow Loop ◽  
Constant Flow Rate

Effect of rotating electromagnetic field on the conductivity of aqueous NaCl solution was investigated by experiments. NaCl solution was circulated at a constant flow rate in the flow loop with a rotating-electromagnetic generating device for a period of time. Then conductivity of NaCl solution was measured at different NaCl solution contractions and rotating electromagnetic fields. Simultaneously, the conductivity was determined for NaCl solution untreated magnetically, as a reference. It was found that the rotating electromagnetic field influenced conductivity of aqueous NaCl solution and made it increased. The mechanism of the effect of the rotating electromagnetic field on conductivity of NaCl solution was also discussed.

Factors Affecting the Efficiency of Absorption Oil Filtration at Constant Flow Rate

1961 ◽  
Author(s):  
Walter J. Ewbank ◽  
C. B. Threlkeld ◽  
C. E. Mitchell ◽  
R. G. Hamilton
Keyword(s):  
Flow Rate ◽  
Constant Flow ◽  
Factors Affecting ◽  
Constant Flow Rate ◽  
Oil Filtration

Study of the Dynamics of the Adsorption of Trichloroethylene (TCE) on Active Carbons

2019 ◽  
Vol 23 (9) ◽  
pp. 30-35
Author(s):  
A.K. Gorelkina ◽  
T.A. Krasnova ◽  
I.V. Tymoshchuk ◽  
N.V. Gora ◽  
N.S. Golubeva
Keyword(s):  
Mass Transfer ◽  
Functional Groups ◽  
Flow Rate ◽  
Operating Time ◽  
Carbon Surface ◽  
Dynamic Adsorption ◽  
Constant Flow ◽  
Active Carbons ◽  
Coal Surface ◽  
Constant Flow Rate

The dynamics of adsorption of trichloroethylene from aqueous solutions on active carbons (AC) of the SKD-515, ABG, Purolat-Standart grades, differing in composition, method of preparation, structure and chemical state of the surface, was studied. The operating time of the filtering layer before breakthrough decreases in the series SKD-515> ABG> Purolat-Standart coal, which is caused by the porous structure of the coal and the nature of the oxygen-containing functional groups on the carbon surface. It was also noted that adsorption is influenced by the interaction of TCE with functional groups of the coal surface. The efficiency of TCE adsorption on various active carbons at a constant flow rate was studied. It was shown that a decrease in the flow rate of the solution through the filter increases the dynamic adsorption capacity, which indisputably confirms the pore-diffusion inhibition of mass transfer.

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