SOME METHODS OF COMBATING SILTING AND ENSURING CONTROLLED FLOW THROUGH SMALL RESTRICTIONS IN HYDRAULIC CONTROL ELEMENTS

1968 ◽  
pp. 393-406
Author(s):  
I.N. KICHIN
Keyword(s):  
Hydraulic Control ◽  
Flow Through ◽  
Controlled Flow

scholarly journals Viscous effects in two-layer, unidirectional hydraulic flow

2010 ◽  
Vol 644 ◽  
pp. 371-394
Author(s):  
MARTIN S. SINGH ◽  
ANDREW McC. HOGG
Keyword(s):  
Control Point ◽  
Lower Boundary ◽  
Internal Gravity Waves ◽  
Velocity Shear ◽  
Hydraulic Control ◽  
Viscous Effects ◽  
Unidirectional Flow ◽  
Boundary Case ◽  
Flow Through ◽  
Layer Flow

Hydraulic equations are derived for a stratified (two-layer) flow in which the horizontal velocity varies continuously in the vertical. Viscosity is included in the governing equations, and the effect of friction in hydraulically controlled flows is examined. The analysis yields Froude numbers which depend upon the integrated inverse square of velocity but reduce to the original layered Froude numbers when velocity is constant with depth. The Froude numbers reveal a critical condition for hydraulic control, which equates to the arrest of internal gravity waves.Solutions are presented for the case of unidirectional flow through a lateral constriction, both with and without bottom drag. In the free-slip lower boundary case, viscosity transports momentum from the faster to the slower layer, thereby shifting the control point downstream and reducing the flux through the constriction. However, while the velocity shear at the interface between the two layers is reduced, the top-to-bottom velocity difference of the controlled solution is increased for larger values of viscosity. This counter-intuitive result is due to the restrictions placed on the flow at the hydraulic control point. When bottom drag is included in the model, the total flux may increase, in some cases exceeding that of the inviscid solution.

scholarly journals Generation of multilayered structures for biomedical applications using a novel tri-needle coaxial device and electrohydrodynamic flow

2008 ◽  
Vol 5 (27) ◽  
pp. 1255-1261 ◽  
Author(s):  
Z Ahmad ◽  
H.B Zhang ◽  
U Farook ◽  
M Edirisinghe ◽  
E Stride ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Controlled Release ◽  
Biomedical Engineering ◽  
Biomedical Applications ◽  
Short Communication ◽  
Multilayered Structures ◽  
Electrohydrodynamic Flow ◽  
Novel Device ◽  
Flow Through ◽  
Controlled Flow

In this short communication, we describe the scope and flexibility of using a novel device containing three coaxially arranged needles to form a variety of novel morphologies. Different combinations of materials are subjected to controlled flow through the device under the influence of an applied electric field. The resulting electrohydrodynamic flow allows us to prepare double-layered bubbles, porous encapsulated threads and nanocapsules containing three layers. The ability to process such multilayered structures is very significant for biomedical engineering applications, for example, generating capsules for drug delivery, which can provide multistage controlled release.

Storage Characteristics of Fresh Swordfish Steaks Stored in Carbon Dioxide-Enriched Controlled (Flow-Through) Atmospheres

1983 ◽  
Vol 46 (5) ◽  
pp. 434-440 ◽  
Author(s):  
V. OBERLENDER ◽  
M. O. HANNA ◽  
R. MIGET ◽  
C. VANDERZANT ◽  
G. FINNE
Keyword(s):  
Carbon Dioxide ◽  
Major Part ◽  
Controlled Atmosphere ◽  
Packaging System ◽  
Brochothrix Thermosphacta ◽  
Flow Through ◽  
Gaseous Atmospheres ◽  
Controlled Flow ◽  
Storage Characteristics ◽  
Lactobacillus Spp

A flow-through controlled atmosphere packaging system using a number of different carbon dioxide-enriched gaseous compositions was demonstrated to be effective in retarding the growth of microorganisms on fresh swordfish steaks held at 2°C for 22 d. During the first 14 d of storage, Pseudomonas spp. either dominated or represented a major part of the microflora of steaks in all gaseous atmospheres tested. However, in atmospheres containing 70% CO2 or in pure CO2, heterofermentative Lactobacillus spp. and Brochothrix thermosphacta were a major part of the microflora, particularly after the 14th day of storage. Both total volatile nitrogen and trimethylamine, often used as quality indicators for fresh seafoods, increased more slowly for swordfish steaks stored in CO2-enriched atmospheres than steaks stored in air. Advantages of using a controlled atmosphere flow-through system for storage of fresh seafoods include: (a) a stable gas composition, (b) individual portions can be removed from a master package without losing or disrupting the gaseous atmosphere, and (c) volatile off-odors which accumulate during storage in sealed CO2-enriched atmospheres are carried off with the flow-through gas.

Study of leakage flow through a spool valve under blocked-actuator port condition—Simulation and experiment

2013 ◽  
Vol 228 (8) ◽  
pp. 1405-1417 ◽  
Author(s):  
Milan K Mondal ◽  
Nirmal K Manna ◽  
Rana Saha
Keyword(s):  
Experimental Results ◽  
Radial Clearance ◽  
Leakage Flow ◽  
Pressure Sensitivity ◽  
Hydraulic Control ◽  
Leakage Flow Rate ◽  
Simulation And Experiment ◽  
Flow Through ◽  
Spool Valve ◽  
Hydraulic Control System

The spool valve is the key component of hydraulic control system, and the performance of spool valve depends on its leakage behaviour. Again, the leakage flow of spool valve is highly susceptible to valve uncertain dimensions, radial clearance and overlap or underlap. In the present work, the relative performance of critically lapped, underlapped and overlapped valves has been demonstrated in terms of leakage flow rate and pressure sensitivity about the metered ports. An approach to explore uncertain dimensions of the valve has been developed using CFD as an investigating tool. The comparison of CFD prediction against experimental results has also been carried out. It is found that the CFD predictions are in excellent agreement with the experimental results.

Magneto-controlled flow-injection device for electrochemical immunoassay of alpha-fetoprotein on magnetic beads using redox-active ferrocene derivative polymer nanospheres

The Analyst ◽  
2019 ◽  
Vol 144 (4) ◽  
pp. 1433-1441 ◽  
Author(s):  
Bin Li ◽  
Wenyuan Pu ◽  
Houxi Xu ◽  
Lilin Ge ◽  
Hang Fai Kwok ◽  
...  
Keyword(s):  
Magnetic Beads ◽  
Alpha Fetoprotein ◽  
Electrochemical Immunoassay ◽  
Injection Device ◽  
Ferrocene Derivative ◽  
Redox Active ◽  
Flow Through ◽  
Polymer Nanospheres ◽  
Controlled Flow ◽  
Electrochemical Immunosensing

A new electrochemical immunosensing protocol by coupling with a magneto-controlled flow-through microfluidic device was developed for the sensitive detection of alpha-fetoprotein (AFP) on magnetic beads (MB) using ferrocene derivative polymer nanospheres (FDNP) as the electroactive mediators.

Multi-layer hydraulic exchange flows

2000 ◽  
Vol 416 ◽  
pp. 269-296 ◽  
Author(s):  
G. F. LANE-SERFF ◽  
D. A. SMEED ◽  
C. R. POSTLETHWAITE
Keyword(s):  
Internal Wave ◽  
Laboratory Experiments ◽  
Rectangular Cross Section ◽  
Wave Mode ◽  
Uniform Density ◽  
Exchange Flow ◽  
Hydraulic Control ◽  
Narrow Channels ◽  
Reservoir Conditions ◽  
Flow Through

Flows between ocean basins are often controlled by narrow channels and shallow sills. A multi-layer hydraulic control theory is developed for exchange flow through such constrictions. The theory is based on the inviscid shallow-water equations and extends the functional approach introduced by Gill (1977) and developed by Dalziel (1991). The flows considered are those in rectangular–cross-section channels connecting two large reservoirs, with a single constriction (sill and/or narrows). The exchange flow depends on the stratification in the two reservoirs, represented as a finite number of immiscible layers of (different) uniform density. For most cases the flow is ‘controlled’ at the constriction and often at other points along the channel (virtual controls) too. As with one- and two-layer hydraulics, controls are locations at which the flow passes from one solution branch to another, and at which (at least) one internal wave mode is stationary. The theory is applied to three-layer flows, which have two internal wave modes, predicting interface heights and layer fluxes from the given reservoir conditions. The theoretical results for three-layer flows are compared to a comprehensive set of laboratory experiments and found to give good agreement. The laboratory experiments also show other features of the flow, such as the formation of waves on the interfaces. The implications of the results for oceanographic flows and ocean modelling are discussed.

Northern Squawfish, Ptychocheilus oregonensis, O2 Consumption Rate and Respiration Model: Effects of Temperature and Body Size

1994 ◽  
Vol 51 (1) ◽  
pp. 8-12 ◽  
Author(s):  
Joseph J. Cech Jr. ◽  
Daniel T. Castleberry ◽  
Todd E. Hopkins ◽  
James H. Petersen
Keyword(s):  
Rainbow Trout ◽  
Body Size ◽  
Cross Sections ◽  
White Muscle ◽  
Consumption Rate ◽  
Live Weight ◽  
Acclimation Temperature ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Flow Through ◽  
Controlled Flow

Northern squawfish, Ptychocheilus oregonensis (live weight range 0.361–1.973 kg), O2 consumption was measured with temperature-controlled, flow-through respirometers for >24 h. Mean standard O2 consumption rate of northern squawfish increased with acclimation temperature: 24.3, 49.1, 75.0, and 89.4 mg∙kg−0.67∙h−1 at 9, 15, 18, and 21 °C, respectively. Q10 analysis showed that O2 consumption rate temperature sensitivity was greatest at the intermediate acclimation temperatures (15–18 °C, Q10 = 4.10), moderate at the lower acclimation temperatures (9–15 °C, Q10 = 3.23), and lowest at the higher acclimation temperatures (18–21 °C, Q10 = 1.80). Overall Q10 was 2.96 (9–21 °C). Body size (W, grams) and temperature (T, degrees Celcius) were related to O2 consumption ([Formula: see text], grams per gram per day) by [Formula: see text]W−0.285∙e0.105T. Northern squawfish red to white muscle ratios significantly exceeded those of rainbow trout, Oncorhynchus mykiss, in cross sections at 50 and 75% of standard length. High metabolic rates and red to white muscle ratios argue for comparability of northern squawfish with active predators such as sympatric rainbow trout.

Development of Improvements to “Controlled Flow” Technology for Large Steam Turbines

2017 ◽  
Author(s):  
B. R. Haller ◽  
G. Singh ◽  
P. R. Millington ◽  
F. C. Mund ◽  
K. Vernon
Keyword(s):  
Leading Edge ◽  
Back Surface ◽  
Steam Turbines ◽  
3D Design ◽  
Design Philosophy ◽  
Previous Design ◽  
Flow Through ◽  
The Mean ◽  
And Performance ◽  
Controlled Flow

The aim of this paper is to present advances in the blading design for large steam turbines — ‘Controlled Flow’ technology. The purpose of the design is to improve the turbine efficiency in a cost neutral manner, adding value for the customer. Controlled Flow is a 3D design philosophy which passes more flow through the efficient middle sections of the blade, and less flow through the comparatively inefficient regions near the endwalls. It has been used for the Impulse Technology Blading ITB guide blades. The current improvement builds on the previous successful Controlled Flow design but incorporates the following new features: - Ultra High Lift for the mean section (at significantly reduced axial width) - Ultra High Back Surface Deflection for the mean section - forward leading edge sweep. The new guide delivers the same radial distribution of absolute fluid exit angle to the runner as the previous design. Confirmatory model turbine tests demonstrated that the new guide delivered a stage efficiency improvement of 0.35%, above an already very high datum level. The endwall sections of the guide are kept the same which maintains the mechanical strength of the diaphragm (same stress and deflection). Therefore, the new design can easily ‘slot-in’ and replace the previous design. The following will be described in detail: - History of the designs/background and design philosophy - Flow physics - Stage optimization and performance prediction - Probabilistic analysis and robustness of the design - Confirmatory model turbine testing and validation (comparison with design predictions).

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