Erosive Wear of Sharp-Edged Orifice Plates

2007 ◽  
Author(s):  
L. I. Ezekoye
Keyword(s):  
Flow Measurement ◽  
Erosive Wear ◽  
Wear Test ◽  
Flow Measurements ◽  
Accident Conditions

Sharp-edged orifice plates are extensively used in flow measurement and flow trimming. In many plant applications where they are used, orifices are installed in systems which are generally clean and debris free. However, there are applications where the system may be either debris laden or exposed, in accident conditions, to debris that could challenge the effectiveness of orifices. This paper presents the results of an accelerated erosive wear test of aluminum and steel orifice plates to determine firstly, how sharp-edged orifices wear in such medium, and secondly, how the wear affects flow measurements.

Investigation of the influence of the flow structure on the accuracy of flow measurement before a hydrometric structure in an open channel

2020 ◽  
pp. 41-44
Author(s):  
Anatoly Kusher
Keyword(s):  
Velocity Profile ◽  
Flow Velocity ◽  
Water Flow ◽  
Flow Measurement ◽  
Water Discharge ◽  
Critical Depth ◽  
Flow Measurements ◽  
Study Results ◽  
Flow Velocity Profile ◽  
Upstream Flow

The reliability of water flow measurement in irrigational canals depends on the measurement method and design features of the flow-measuring structure and the upstream flow velocity profile. The flow velocity profile is a function of the channel geometry and wall roughness. The article presents the study results of the influence of the upstream flow velocity profile on the discharge measurement accuracy. For this, the physical and numerical modeling of two structures was carried out: a critical depth flume and a hydrometric overfall in a rectangular channel. According to the data of numerical simulation of the critical depth flume with a uniform and parabolic (1/7) velocity profile in the upstream channel, the values of water discharge differ very little from the experimental values in the laboratory model with a similar geometry (δ < 2 %). In contrast to the critical depth flume, a change in the velocity profile only due to an increase in the height of the bottom roughness by 3 mm causes a decrease of the overfall discharge coefficient by 4…5 %. According to the results of the numerical and physical modeling, it was found that an increase of backwater by hydrometric structure reduces the influence of the upstream flow velocity profile and increases the reliability of water flow measurements.

The Accuracy of Transit Time Flow Measurement in Predicting Graft Patency after Coronary Artery Bypass Grafting

2013 ◽  
Vol 8 (6) ◽  
pp. 416-419 ◽  
Author(s):  
Patrick F. Walker ◽  
William T. Daniel ◽  
Emmanuel Moss ◽  
Vinod H. Thourani ◽  
Patrick Kilgo ◽  
...  
Keyword(s):  
Coronary Artery ◽  
Coronary Artery Bypass Grafting ◽  
Transit Time ◽  
Pulsatility Index ◽  
Flow Measurement ◽  
Artery Bypass ◽  
Graft Patency ◽  
Bypass Grafting ◽  
Flow Measurements ◽  
Time Flow

Objective Transit time flow measurement (TTFM) is a method used to assess intraoperative blood flow after vascular anastomoses. Angiography represents the criterion standard for the assessment of graft patency after coronary artery bypass grafting (CABG). The purpose of this study was to compare flow measurements from TTFM to diagnostic angiography. Methods From October 9, 2009, to April 30, 2012, a total of 259 patients underwent robotic-assisted CABG procedures at a single institution. Of these, 160 patients had both TTFM and either intraoperative or postoperative angiography of the left internal mammary artery to the left anterior descending coronary artery graft. Transit time flow measurements were obtained after completion of the anastomosis and after administration of protamine before chest closure. Transit time flow measurement assessment included pulsatility index, diastolic fraction, and flow (milliliters per minute). Angiograms were graded according to the Fitzgibbon criteria. The patients were grouped according to angiographic findings, with perfect grafts defined as FitzGibbon A and problematic grafts defined as either Fitzgibbon B or O. Results Overall, there were 152 (95%) of 160 angiographically perfect grafts (FitzGibbon A). Of the eight problematic grafts, five were occluded (Fitzgibbon O) and three had significant flow-limiting lesions (FitzGibbon B). Two patients had intraoperative graft revision after completion angiography, one had redo CABG during the same hospitalization, and five were treated with percutaneous coronary intervention. A significant difference was seen in mean ± SD flow (34.3 ± 16.8 mL/min vs 23.9 ± 12.5 mL/min, P = 0.033) between patent and nonpatent grafts but not in pulsatility index (1.98 ± 0.76 vs 1.65 ± 0.48, P = 0.16) or diastolic fraction (73.5% ± 8.45% vs 70.9% ± 6.15%, P = 0.13). Conclusions Although TTFM can be a useful tool for graft assessment after CABG, false negatives can occur. Angiography remains the criterion standard to assess graft patency and quality of the anastomosis after CABG.

Enhancement of flow measurement for graft verification

2019 ◽  
Vol 27 (8) ◽  
pp. 646-651
Author(s):  
Yury Y Vechersky ◽  
Vasily V Zatolokin ◽  
Boris N Kozlov ◽  
Aleksandra A Nenakhova ◽  
Vladimir M Shipulin
Keyword(s):  
Coronary Artery ◽  
Transit Time ◽  
Flow Measurement ◽  
Artery Bypass ◽  
Coronary Bypass ◽  
Flow Measurements ◽  
Technical Problems ◽  
Technical Errors ◽  
Time Flow ◽  
Coronary Bypass Grafts

Background We aimed to evaluate multiple transit-time flow measurements during coronary artery bypass grafting. Methods Transit-time flow measurements were performed first on the arrested heart both with and without a proximal snare on the target coronary artery, second, after weaning from cardiopulmonary bypass, and third, before chest closure. Results Among the 214 grafts considered, 9 (4.2%) were patent and 6 (2.8%) were failing. In the failed grafts, an abnormal transit-time flow was found during the first measurement, in 5 (2.3%) cases with a proximal snare and in one (0.47%) without a snare. In these cases, technical errors with the distal anastomoses were found and immediately corrected. A problem with the proximal anastomosis was found in one graft during the second measurement and corrected right away. Bending due to excessive length was found in 2 (0.93%) grafts during the third measurement, and graft repositioning was performed. The first transit-time flow measurement showed that mean graft flow was significantly decreased with a proximal snare compared to without a proximal snare, throughout the entire coronary territory. Pulsatility index during the first transit-time flow measurement was higher with a proximal snare than without one. Conclusions The 3-time transit-time flow measurement strategy makes it possible to verify and immediately correct technical problems with coronary bypass grafts.

Knowledge-based systems and operational hydrology

1991 ◽  
Vol 18 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Slobodan P. Simonovic
Keyword(s):  
Expert System ◽  
Flow Measurement ◽  
Knowledge Based Systems ◽  
Flow Measurements ◽  
Knowledge Based ◽  
Original Concept ◽  
System Water ◽  
Potential Use ◽  
Selection Of

Knowledge-based systems were brought to the attention of hydrologists almost a decade ago. The application of knowledge-based systems technology is natural and appropriate for the field of hydrology because it contains numerous procedures developed from theory, actual practice, and experience. The emphasis of the present paper is on demystifying knowledge-based systems of artificial intelligence. After a detailed review of the most important applications to the field of hydrology, the original concept for applying knowledge-based technology is presented. The discussion ends with the list of possible benefits from the application of knowledge-based technology. An expert system for the selection of a suitable method for flow measurement in open channels is used as a case study to illustrate the discussion in the paper. The system has been designed for potential use in Environment Canada. Key words: expert system, water resources, hydrology, flow measurements.

The Role of Particle Motion in Abrasive and Erosive Wear

2005 ◽  
Author(s):  
I. M. Hutchings
Keyword(s):  
Abrasive Wear ◽  
Particle Motion ◽  
Erosive Wear ◽  
Wear Test ◽  
Wear Particle ◽  
Analytical Models ◽  
Particle Rotation ◽  
Wear Rates ◽  
Hard Particles ◽  
Three Body

The traditional classification of abrasive wear into two-and three-body, high and low stress, open and closed etc. does not recognise the essential importance of particle motion, which is better described as either sliding or rolling. Abrasive wear tests with free abrasives can produce either type of motion, depending on the test conditions. The widely-used dry sand rubber wheel test often produces both motions over different areas of the sample. The more recent micro-scale abrasion test tends to favour one or the other over most of the wear scar area. Analytical models can be developed which allow the dominant particle motion to be predicted, and mapped using readily accessible parameters. In erosive wear, particle motion can also be important; recent work suggests that particle rotation is imparted in some types of erosive wear test, and that it may be responsible for the differences in wear rate found in tests under nominally identical conditions with different designs of apparatus. It is suggested that in the use of laboratory abrasion and erosion tests, and in the analysis of practical instances of wear by hard particles, close attention should be paid to the nature of particle motion, since this will influence both the dominant wear mechanisms and also the wear rates.

Review of Critical Flowmeters for Gas Flow Measurements

1962 ◽  
Vol 84 (4) ◽  
pp. 447-457 ◽  
Author(s):  
B. T. Arnberg
Keyword(s):  
Mass Flow ◽  
Flow Measurement ◽  
Gas Flow ◽  
Flow Measurements ◽  
Flow Rates ◽  
Real Gas ◽  
Discharge Coefficients ◽  
Critical Nozzles ◽  
Mass Flow Rates ◽  
Flow Functions

Critical flowmeters for accurately measuring the mass flow rates of nonreacting real gases were reviewed. Discussions were presented on theoretical flow functions, on parameters for correlating discharge coefficients, and on the importance of real gas properties. The performance characteristics of critical nozzles and orifices of several designs were reviewed. Approaches were discussed to problems which must be researched before the fullest potential of this type of flow measurement can be realized.

scholarly journals Properties of coatings created by HVOF technology using micro-and nano-sized powder

2019 ◽  
Vol 63 (2) ◽  
pp. 86-93 ◽  
Author(s):  
A. Guzanová ◽  
J. Brezinová ◽  
D. Draganovská ◽  
P.O. Maruschak
Keyword(s):  
Corrosion Resistance ◽  
Cyclic Loading ◽  
Linear Polarization ◽  
Elevated Temperatures ◽  
Erosive Wear ◽  
Wear Test ◽  
Thermal Cycles ◽  
Properties Of Coatings ◽  
Grain Sizes ◽  
Sprayed Coatings

Abstract The paper focuses on assessment the resistance of hot-sprayed coatings applied by HVOF technology (WC–Co–Cr created using powder of two different grain sizes) against erosive wear by dry-pot wear test in a pin mill at two sample angles. As these coatings are designated for the environment with varying elevated temperatures and often are in contact with the abrasive, the coatings have been subjected to thermal cyclic loading and their erosive resistance has been determined in as-sprayed condition and after the 5th and 10th thermal cycles. The corrosion resistance of coatings was evaluated by linear polarization (Tafel analysis).

scholarly journals Assessment of Intraoperative Flow Measurement as a Quality Control During Carotid Endarterectomy: A Single-Center Analysis

2020 ◽  
pp. 145749692097113
Author(s):  
A. E. Cyrek ◽  
P. Husen ◽  
S. Radünz ◽  
A. Pacha ◽  
C. Weimar ◽  
...  
Keyword(s):  
Quality Control ◽  
Carotid Endarterectomy ◽  
Flow Measurement ◽  
Intraoperative Imaging ◽  
Intraoperative Ultrasound ◽  
Flow Measurements ◽  
Technical Errors ◽  
Significant Difference ◽  
Artery Disease ◽  
Associated Risk Factors

Background: To evaluate the technical results of the arterial repair, a variety of intraoperative imaging and assessment techniques can be used during carotid endarterectomy. The aim of the study was to evaluate the usefulness of intraoperative ultrasound flow measurement as a quality control after primary carotid endarterectomy in the setting of a teaching hospital. Methods: One hundred and seven consecutive carotid endarterectomies were performed over 24 months at our institution. Retrospectively acquired demographics, intraoperative flow measurements, duplex results, revisions, and surgical outcomes were reviewed. Postoperative 30-day transient ischemic attack, stroke, and death rates were analyzed. Results were compared with ultrasound flow measurement and duplex ultrasonography. Results: From March 2013 to March 2015, 107 primary consecutive carotid endarterectomies were performed in 107 patients (71% male, 29% female). The age ranged from 51 to 81 years with a mean age of 68 ± 4 years. Associated risk factors included diabetes 89 (83%), smoking 92 (86%), hypertension 94 (87.8%), chronic renal insufficiency 71 (66%), and coronary artery disease 57 (53%). Early postoperative duplex scans in all 107 patients showed no significant changes from intraoperative findings. The ipsilateral stroke and death rate in this study was 0 (0/107) and 30-day death and stroke rate was also 0 (0/107), with no significant difference between trainees and senior surgeons. Three patients (2.8 %) had flow <100 mL/min and two of them were revised after completion contrast angiography. Conclusion: The findings of this study indicate that the intraoperative flow measurement is an alternative method for detecting technical errors and a tool for quality control imaging. Especially for the trainees, it makes sense to ensure effectiveness of the procedure upon its completion and to assess the technical adequacy of carotid endarterectomy.

The Systematic Uncertainty of Laboratory Flow Calibrations

1998 ◽  
Vol 120 (1) ◽  
pp. 19-22 ◽  
Author(s):  
D. R. Keyser
Keyword(s):  
Water Flow ◽  
Systematic Uncertainty ◽  
Flow Measurement ◽  
Cold Water ◽  
Liquid Hydrocarbon ◽  
Hydrocarbon Fuels ◽  
Interlaboratory Comparisons ◽  
Calibration Laboratory ◽  
Flow Measurements ◽  
A Value

There are two axioms applicable to this paper: the first is that no flowmeter can be more accurate than the laboratory which calibrated it; the second that no uncalibrated flowmeter can be more accurate than a like one that is calibrated in a recognized standards laboratory. The fundamental systematic uncertainty in flow measurement is that inherited from the flow calibration laboratory. This paper focuses on ascertaining this fundamental systematic uncertainty by deriving from the published instances of interlaboratory comparisons a value in which one may be 95 percent confident. For water flow measurements, this value turns out to be ±0.28 percent, and for liquid hydrocarbon fuels it is ±0.77 percent. Cold water calibrations are the most accurate.

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