Flow Rate Dependence of Soil Hydraulic Characteristics

2001 ◽  
Vol 65 (1) ◽  
pp. 35-48 ◽  
Author(s):  
D. Wildenschild ◽  
J.W. Hopmans ◽  
J. Simunek
Keyword(s):  
Flow Rate ◽  
Rate Dependence ◽  
Hydraulic Characteristics ◽  
Soil Hydraulic

Stabilization of the Speed of the Hydraulic Motor Through Throttle Compensation for Volume Losses

2020 ◽  
Vol 26 (3) ◽  
pp. 126-130
Author(s):  
Krasimir Kalev
Keyword(s):  
Flow Rate ◽  
Hydraulic Drive ◽  
Pressure Change ◽  
Operating Conditions ◽  
Drive System ◽  
Inlet Pressure ◽  
Schematic Diagram ◽  
Hydraulic Characteristics ◽  
Hydraulic Motor ◽  
Flow Through

AbstractA schematic diagram of a hydraulic drive system is provided to stabilize the speed of the working body by compensating for volumetric losses in the hydraulic motor. The diagram shows the inclusion of an originally developed self-adjusting choke whose flow rate in the inlet pressure change range tends to reverse - with increasing pressure the flow through it decreases. Dependent on the hydraulic characteristics of the hydraulic motor and the specific operating conditions.

Luminal flow rate regulates proximal tubule H-HCO3 transporters

1992 ◽  
Vol 262 (1) ◽  
pp. F47-F54 ◽  
Author(s):  
P. A. Preisig
Keyword(s):  
Proximal Tubule ◽  
Flow Rate ◽  
Initial Rate ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Rate Dependence ◽  
Unstirred Layer ◽  
Disulfonic Acid ◽  
Luminal Flow

In vivo microperfusion was used to examine the mechanism of luminal flow rate dependence of proximal tubule acidification. Luminal flow rate was acutely changed between 5 and 40 nl/min, while luminal and peritubular capillary composition were held constant. With inhibition of basolateral membrane base transport by peritubular 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), cell pH (pHi) provides a sensitive index of apical membrane H secretory activity. At a luminal perfusate [HCO3] of 25 mM, progressive increases in luminal flow rate (5----15----25----40 nl/min) caused progressive increases in pHi. This effect was of a smaller magnitude with a luminal perfusate [HCO3] of 60 mM and was further decreased at a luminal perfusate [HCO3] of 100 mM. This pattern of diminished flow rate dependence at higher luminal [HCO3] is consistent with the presence of a luminal unstirred layer, whose composition can be modified by luminal flow rate. The activity of the apical membrane Na-H antiporter, assayed as the initial rate of pHi recovery from an acid load in the presence of peritubular DIDS, was faster at 40 compared with 5 nl/min. Basolateral membrane Na-3HCO3 symporter activity, assayed as the initial rate of pHi recovery from an alkali load in the absence of luminal and peritubular chloride, was faster at 40 compared with 5 nl/min. This effect was eliminated by luminal amiloride, suggesting an indirect effect of flow mediated by changes in pHi secondary to flow rate-dependent changes in apical membrane Na-H antiporter activity. In summary, increases in luminal flow rate directly increase apical membrane H secretion, possibly by modification of a luminal unstirred layer.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Intermittent Chaos in the CSTR Bray–Liebhafsky Oscillator-Specific Flow Rate Dependence

2020 ◽  
Vol 8 ◽  
Author(s):  
Itana Nuša Bubanja ◽  
Ana Ivanović-Šašić ◽  
Željko Čupić ◽  
Slobodan Anić ◽  
Ljiljana Kolar-Anić
Keyword(s):  
Flow Rate ◽  
Rate Dependence ◽  
Specific Flow Rate ◽  
Specific Flow ◽  
Intermittent Chaos

scholarly journals Influences of flow rate and baffle spacing on hydraulic characteristics of a novel baffle dropshaft

2020 ◽  
Vol 13 (3) ◽  
pp. 233-242
Author(s):  
Xi-chen Wang ◽  
Jian Zhang ◽  
Zong-fu Fu ◽  
Hui Xu ◽  
Ting-yu Xu ◽  
...  
Keyword(s):  
Flow Rate ◽  
Hydraulic Characteristics

EXPERIMENTAL STUDY OF BAR FORMATION IN SAND BED CHANNEL

2016 ◽  
Vol 78 (5-3) ◽  
Author(s):  
Duratul Ain Tholibon ◽  
Junaidah Ariffin ◽  
Jazuri Abdullah ◽  
Juliana Idrus
Keyword(s):  
Experimental Study ◽  
Flow Rate ◽  
Experimental Work ◽  
Large Scale ◽  
Sediment Supply ◽  
Hydraulic Characteristics ◽  
Flow Rates ◽  
Physical Mechanisms ◽  
Bed Slope ◽  
Bar Formation

A large number of studies both theoretical and experimental have been devoted to understand the physical mechanisms underlying the bar formation. This can be investigated by carrying out an experimental work in an erodible sand bed channel using a large-scale physical river model. The study included the various hydraulic characteristics with steady flow rates and sediment supply. An experimental work consists of four matrices of flow rate and channel width with other variables namely grains size and bed slope were kept constant. Details of bar profile development that generated using Surfer, a software used for 3D elevation plots are included.

Numerical Investigation on the Heat Transfer Enhancement Behavior Outside Longitudinal Finned Tubes

2018 ◽  
Author(s):  
Yujia Zhou ◽  
Hanliang Bo ◽  
Jingyu Du
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Transfer Process ◽  
Numerical Results ◽  
Transfer Model ◽  
Hydraulic Characteristics ◽  
Finned Tubes ◽  
Smooth Tubes

With the purpose of enhancement of heat transfer performance and reduction of the volume of steam generator (SG), a structure of longitudinal finned tubes was proposed to replace the smooth tubes of SG in this paper. Taking the SG smooth tubes of Daya bay Nuclear Power plant as a reference, the simplified heat transfer model of new longitudinal finned tubes was established by ANSYS CFX. Three-dimensional numerical model was developed to investigate the fluid-solid coupled thermal hydraulic characteristics of different types of the longitudinal finned tubes compared with the smooth tubes. Analysis of calculation results were sufficiently discussed for the effect of mass flow rate, fin array, solid thermal conductivity and frictional resistance. The numerical results revealed that the heat transfer coefficient increase with the increasing mass flow rate in the secondary side. The material of the tubes has significantly influence on the heat transfer process. Different flow conditions have different thermal hydraulic characteristics. The evaluated criterion to judge the enhancement of the heat transfer of the coupled process was also proposed. The numerical results can provide some useful guidance for design optimization of longitudinal finned tubes in SG.

Hydraulic Characteristics of Pipelines Transporting Hot Waxy Crudes

2006 ◽  
Author(s):  
Jun Chen ◽  
Jinjun Zhang ◽  
Hongying Li
Keyword(s):  
Flow Rate ◽  
Pour Point ◽  
Friction Loss ◽  
Low Flow ◽  
Critical Flow ◽  
Outlet Temperature ◽  
Hydraulic Characteristics ◽  
Critical Flow Rate ◽  
Waxy Crude ◽  
Oil Pipeline

Waxy crudes are generally pipelined by means of heating. In general, the friction loss of a pipeline decreases with decreasing flow rate. This is the case of isothermal pipeline. However, a hot oil pipeline operated at low flow rate might show a contrary case, i.e. friction-loss increases with decreasing flow rate. This is an unstable operation state and may result in disastrous consequence of flow ceasing if tackled improperly. For a waxy crude pipeline, this may also be exaggerated by the non-Newtonian flow characteristics at temperatures near the pour point. That is to say, there may exist a critical flow rate for pipelines transporting heated waxy crude, and in order to ensure safe operation, the flow rate of a pipeline transporting hot oil should be no less than this critical flow rate. Based on theoretical analysis and can study, the hydraulic characteristics of pipelines transporting hot waxy crudes was investigated, and an empirical model was developed correlating the critical flow rate QC and the pipelining parameters, such as the average overall heat transfer coefficient, the ground temperature, the heating temperature, etc. Another relationship was found between TZC, the outlet temperature of the pipeline corresponding to the critical flow rate, and the critical flow rate. This TZC is also the lowest pipeline outlet temperature that ensures the normal pipelining operation state. Case study on a 720mm O.D. pipeline transporting heated Daqing waxy crude with a pour point of 36 °C showed that the TZC was in a range of 31∼34.2°C.

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