Flow Structure in Continuous Flow Electrophoresis Chambers

1981 ◽  
Vol 9 ◽  
Author(s):  
J. A. DEIBER ◽  
D. A. Saville
Keyword(s):  
Continuous Flow ◽  
Cooling System ◽  
Finite Difference Methods ◽  
Axial Flow ◽  
Approximate Solutions ◽  
Low Flow ◽  
Small Temperature ◽  
Higher Power ◽  
Hydrodynamic Processes ◽  
Electro Osmotic Flow

ABSTRACTThere are at least two ways that hydrodynamic processes can limit continuous flow electrophoresis. One arises from the sensitivity of the flow to small temperature gradients, especially at low flow rates and power levels. This sensitivity can be suppressed, at least in principle, by providing a carefully tailored, stabilizing temperature gradient in the cooling system that surrounds the flow channel. At higher power levels another limitation arises due to a restructuring of the main flow. This restructuring is caused by buoyancy, which is in turn affected by the electro-osmotic crossflow. Approximate solutions to appropriate partial differential equations have been computed by finite difference methods. One set of results is described here to illustrate the strong coupling between the structure of the main (axial) flow and the electro-osmotic flow.

Overheating and Frequent Thermal Cycling of Outdoor Electronic Cabinets in Cold Climates

1999 ◽  
Vol 121 (1) ◽  
pp. 50-54 ◽  
Author(s):  
E. B. Zimmerman ◽  
H. Hegab ◽  
G. T. Colwell
Keyword(s):  
Thermal Cycling ◽  
Cooling System ◽  
Experimental Testing ◽  
Low Cost ◽  
Effective Means ◽  
Axial Flow ◽  
Ambient Air ◽  
Low Flow ◽  
Transient Temperature ◽  
Forced Air

Telephone companies use electronics to route calls between customers. The electronics are generally closely packed together and placed in steel containers outdoors. Forced air convection utilizing the outside ambient air is an effective means to cool outdoor electronic cabinets and is generally the system of choice given the relatively low cost and simplicity when compared to alternative cooling methods. Simple axial flow fans are typically turned on and off by a thermostat located inside the cabinet to keep the inside air temperature below a predetermined maximum. This simple cooling system is usually effective during summer operations. However, it may result in overheating and excessive thermal cycling in winter operations. Transient temperature data from experiments on a telecommunications cabinet is presented illustrating this problem. One possible solution to this problem is using continuously operating fans at low flow rates. This solution was arrived at through a combination of experimental testing and numerical simulation.

scholarly journals Novel assessment of intestinal anastomotic perfusion using ICG SPY in a continuous flow LVAD patient

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Daniel Kaufman ◽  
Danny Sherwinter ◽  
Ron Kaleya ◽  
Paul C Saunders
Keyword(s):  
Continuous Flow ◽  
Axial Flow ◽  
Colon Resection ◽  
Left Ventricular ◽  
Heartmate Ii ◽  
Ventricular Assist ◽  
Intestinal Anastomoses ◽  
First Case ◽  
Left Ventricular Assist ◽  
Axial Flow Pump

Abstract HeartMate II left ventricular assist device (LVAD) assists heart failure patients by generating continuous flow via axial flow pump placed in the left ventricle. Little is known of the effect of continuous flow on intestinal anastomoses. This is the first case visually documenting altered perfusion patterns in patients with LVADs using indocyanine green (ICG). A 72-year-old male required a colon resection, for adenocarcinoma, following implantation of an LVAD. Perfusion of the anastomosis was evaluated using indocyanine. During the assessment, an unusual perfusion pattern was noticed. Normally, flow as measured by SPY is seen as an initial blush of contrast followed by a gradual, pulsatile increase in the progression of the indocyanine through the tissues. In this patient, instead of the usual initial blush, a continuous beam of ICG was seen to flow though the blood vessels. This novel perfusion pattern is consistent with flow generated from LVAD.

Analysis of a Large-Scale Cooling System Fan Gearbox Loads

2017 ◽  
Author(s):  
Charles H. O. Lombard ◽  
Daniel N. J. Els ◽  
Jacques Muiyser ◽  
Albert Zapke
Keyword(s):  
Large Scale ◽  
Cooling System ◽  
Axial Flow ◽  
Output Shaft ◽  
Blade Loading ◽  
Operational Conditions ◽  
Power Stations ◽  
Reverse Loading ◽  
Air Cooled Condensers ◽  
Input Side

South Africa’s coal-fired power stations use super heated steam to drive generator turbines. In arid regions, air-cooled condensers (ACCs) are used to condense the process steam. These ACCs consists of an array of over 200 axial flow fans, each driven by a motor via a reduction gearbox. Distorted fan inlet air flow conditions cause transient blade loading, which results in variations in output shaft bending and torque. A measurement project was conducted where the input and output shaft of such a gearbox were instrumented with strain gauges and wireless bridge amplifiers. Gearbox shaft speed and vibration were also measured. Torsional and bending strains were measured for a variety of operational conditions, where correlations were seen between gearbox loading and wind conditions. The input side experienced no unexpected loads from the motor or changing wind conditions, whereas output shaft loading was influenced by the latter. Digital filters were applied to identify specific bending components, such as the influence of fan hub misalignment and dynamic blade loading. Reverse loading of the gearbox was measured during the fan stop period, and vibration analysis revealed torsional and gearbox vibrations. This investigation documented reliable full scale ACC gearbox loads.

Progress of the 40 MW-Class Advanced Humid Air Turbine Tests

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Manabu Yagi ◽  
Hidefumi Araki ◽  
Hisato Tagawa ◽  
Tomomi Koganezawa ◽  
Chihiro Myoren ◽  
...  
Keyword(s):  
Metal Surface ◽  
Control Method ◽  
Cooling System ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Test Facility ◽  
Humid Air ◽  
Air Turbine ◽  
Calculation Results ◽  
Flow Compressor

A 40 MW-class test facility has been constructed to verify practicability of applying the advanced humid air turbine (AHAT) system to a heavy-duty gas turbine. Verification tests have been carried out from January 2012, and interaction effects between the key components were established. First, water atomization cooling (WAC) was confirmed to contribute to both increased mass flow rate and pressure ratio for the axial-flow compressor. The good agreement between measured and calculated temperatures at the compressor discharge was also confirmed. These results demonstrated the accuracy of the developed prediction model for the WAC. Second, a control method that realized both flame stability and low nitrogen oxides (NOx) emissions was verified. Although the power output and air humidity were lower than the rated values, NOx concentration was about 10 ppm. Finally, a hybrid nozzle cooling system, which utilized both compressor discharged air and humid air, was developed and tested. The metal surface temperatures of the first stage nozzles were measured, and they were kept under the permissible metal temperature. The measured temperatures on the metal surface reasonably corresponded with calculation results.

Flow-Induced Instability of Heat-Exchanger Tubes due to Axial Flow in a Diffuser-Shaped, Loose Intermediate Support

1989 ◽  
Vol 111 (4) ◽  
pp. 428-434 ◽  
Author(s):  
A. Yasuo ◽  
M. P. Paidoussis
Keyword(s):  
Heat Exchanger ◽  
Fluid Dynamic ◽  
Axial Flow ◽  
Low Flow ◽  
Baffle Plate ◽  
Intermediate Point ◽  
Flow Passage ◽  
Fluid Forces ◽  
Dynamic Damping ◽  
Flow Velocities

In some heat exchangers and steam generators, the flow is predominantly axial, and the external fluid flows between baffled compartments through enlarged holes in the baffles around the heat exchanger tubes. Thus, the tube is subjected to relatively high flow velocities over small portions of its length, in the baffle locations. In this paper, the dynamics of such an idealized system is investigated, involving a cylindrical beam with pinned ends in axial flow, going through a baffle plate of finite thickness at some intermediate point, with small radial clearance. The fluid forces along the tube are formulated in a manner reminiscent of the transfer-matrix technique, since the character of these forces changes drastically along the tube. The fluid forces are determined approximately by means of potential flow theory, and viscous effects are taken into account only in a global sense. It was found that if the flow passage through the baffle plate is diffuser-shaped, negative fluid-dynamic damping is generated therein, destabilizing the system and leading to flutter at relatively low flow velocities. The instability depends critically on the shape of the hole through the baffle and on the clearance; thus a convergent-type flow passage does not lead to instability. The negative fluid-dynamic damping is linearly proportional to the flow velocity through the baffle.

Subcooled Flow Boiling in Circumferentially Nonuniform and Uniform Heated Vertical Channels With Downward Flow

2000 ◽  
Vol 122 (3) ◽  
pp. 620-625 ◽  
Author(s):  
Q. Peatiwala ◽  
R. D. Boyd,
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Axial Flow ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
Single Side ◽  
Flow Boiling Heat Transfer ◽  
Higher Power ◽  
Heated Length

Results are presented for new experimental data for subcooled flow boiling heat transfer in circumferentially nonuniform (single-side) and uniformly heated tubes. Although the Liu-Winterton correlation had better agreement at low power levels and axial locations, Shah’s correlation had better agreement at higher power levels and at axial locations near the center of the heated length. Both correlations overpredicted the data near the exit. Therefore, additional correlational developmental work is needed for local (axial) flow boiling heat transfer in circumferentially nonuniform heated channels. [S0022-1481(00)00603-4]

Low Reynolds-Number Experiments in an Axial-Flow Turbomachine

1964 ◽  
Vol 86 (3) ◽  
pp. 257-295 ◽  
Author(s):  
J. Neustein
Keyword(s):  
Reynolds Number ◽  
Guide Vane ◽  
Axial Flow ◽  
Reynolds Numbers ◽  
Low Flow ◽  
Working Fluid ◽  
Low Reynolds Numbers ◽  
Blade Row ◽  
Overall Performance ◽  
Low Reynolds

The performance of a single-stage, axial-flow turbomachine was studied experimentally at low Reynolds numbers. The study was made with a turbomachine modeled from a large jet-engine type of axial-flow compressor. Low Reynolds numbers were obtained by using a mixture of glycerine and water as the working fluid. The overall performance was determined over a range of Reynolds numbers RT (based on rotor-tip speed and rotor chord) from 2000 to 150,000. The flow rate at each Reynolds number was varied from near shutoff to the maximum permitted by the turbomachine-tunnel systems. Blade-row characteristics were studied by means of quantitative flow surveys before and after each blade row, and by means of extensive flow-visualization experiments within each blade row. The investigation established that sudden or critical changes in performance do not occur in the type of machine tested, between RT of 150,000 and 20,000. Below 20,000 the performance deteriorated more rapidly. A relatively sharp change in performance occurred between RT of 20,000 and 10,000. The results clarified many of the viscous flow details in each blade row which are associated with the deterioration of performance. These effects were very pronounced at RT of 4000 and below. Consequently, a considerable part of the paper is concerned with results obtained at these lower Reynolds numbers. From the point of view of a designer, information is presented in regard to overall performance, guide-vane turning, and guide-vane and stator total-pressure losses, all as functions of Reynolds number. These results are expected to be indicative of performance in turbomachines similar to the one tested here. Other details are concerned with problems such as wall boundary layers, flow reversal at low flow coefficients, lip-clearance flow, flow patterns near shutoff, and flow comparisons in stators with rotating and stationary hubs.

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