Ehsan Ardekani, Foad Farhani, Mohammad Ali Ardekani
{"title":"Determination of flow angle from measurements of vortex shedding frequency downstream of a triangular bluff model using a single-sensor hot-wire probe","authors":"Ehsan Ardekani, Foad Farhani, Mohammad Ali Ardekani","doi":"10.1016/j.flowmeasinst.2024.102731","DOIUrl":null,"url":null,"abstract":"<div><div>Experimental aerodynamic studies often require precise measurements of flow angles. However, the conventional multi-hole probe is unsuitable for measuring small flow angles or for use under low-velocity conditions. To overcome these limitations, a new method has been proposed based on measuring the frequency of vortex shedding downstream of a non-polar symmetric body. This technique utilizes a single-sensor hot-wire probe to measure the frequency of the vortex shedding from an equilateral triangular model at different flow angles (<span><math><mrow><mi>α</mi><mo>)</mo></mrow></math></span> by rotating the model using a rotating mechanism. Subsequently, the Strouhal number (St) is determined for each flow angle from the measured vortex shedding frequencies. An empirical correlation is then obtained between the Strouhal number and the flow angle of the form <span><math><mrow><mi>α</mi><mo>=</mo><msup><mi>f</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup><mrow><mo>(</mo><mrow><mi>S</mi><mi>t</mi></mrow><mo>)</mo></mrow></mrow></math></span>, considering the condition where the Strouhal number is solely a function of the flow angle. The range of flow angles for which the proposed method is applicable, along with acceptable repeatability of the vortex shedding frequency and suitable Strouhal number sensitivity to the variations in the flow angle, was determined. An empirical correlation <span><math><mrow><mi>α</mi><mo>=</mo><mo>−</mo><mn>4153.4</mn><msup><mrow><mi>S</mi><mi>t</mi></mrow><mn>2</mn></msup><mo>−</mo><mn>1819.9</mn><mi>S</mi><mi>t</mi><mo>+</mo><mn>189.51</mn></mrow></math></span> was established, which can be used to determine flow angles in the range of ±10° with an accuracy of 1°. For this purpose, the triangular model is fixed at an angle of 33° to the principal coordinates. The probe is positioned downstream of the model in the defined range: <span><math><mrow><mn>3</mn><mo>≤</mo><mi>x</mi><mo>/</mo><mi>a</mi><mo><</mo><mn>25</mn></mrow></math></span>, <span><math><mrow><mn>4.5</mn><mo>≤</mo><mi>y</mi><mo>/</mo><mi>a</mi><mo>≤</mo><mn>5.1</mn></mrow></math></span>, where <span><math><mrow><mi>a</mi></mrow></math></span> is the side of the equilateral triangular model, and <span><math><mrow><mi>x</mi></mrow></math></span> and <span><math><mrow><mi>y</mi></mrow></math></span> are probe distances in the flow and perpendicular to the flow direction.</div></div>","PeriodicalId":50440,"journal":{"name":"Flow Measurement and Instrumentation","volume":"100 ","pages":"Article 102731"},"PeriodicalIF":2.3000,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Flow Measurement and Instrumentation","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0955598624002115","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, MECHANICAL","Score":null,"Total":0}
引用次数: 0
Abstract
Experimental aerodynamic studies often require precise measurements of flow angles. However, the conventional multi-hole probe is unsuitable for measuring small flow angles or for use under low-velocity conditions. To overcome these limitations, a new method has been proposed based on measuring the frequency of vortex shedding downstream of a non-polar symmetric body. This technique utilizes a single-sensor hot-wire probe to measure the frequency of the vortex shedding from an equilateral triangular model at different flow angles ( by rotating the model using a rotating mechanism. Subsequently, the Strouhal number (St) is determined for each flow angle from the measured vortex shedding frequencies. An empirical correlation is then obtained between the Strouhal number and the flow angle of the form , considering the condition where the Strouhal number is solely a function of the flow angle. The range of flow angles for which the proposed method is applicable, along with acceptable repeatability of the vortex shedding frequency and suitable Strouhal number sensitivity to the variations in the flow angle, was determined. An empirical correlation was established, which can be used to determine flow angles in the range of ±10° with an accuracy of 1°. For this purpose, the triangular model is fixed at an angle of 33° to the principal coordinates. The probe is positioned downstream of the model in the defined range: , , where is the side of the equilateral triangular model, and and are probe distances in the flow and perpendicular to the flow direction.
期刊介绍:
Flow Measurement and Instrumentation is dedicated to disseminating the latest research results on all aspects of flow measurement, in both closed conduits and open channels. The design of flow measurement systems involves a wide variety of multidisciplinary activities including modelling the flow sensor, the fluid flow and the sensor/fluid interactions through the use of computation techniques; the development of advanced transducer systems and their associated signal processing and the laboratory and field assessment of the overall system under ideal and disturbed conditions.
FMI is the essential forum for critical information exchange, and contributions are particularly encouraged in the following areas of interest:
Modelling: the application of mathematical and computational modelling to the interaction of fluid dynamics with flowmeters, including flowmeter behaviour, improved flowmeter design and installation problems. Application of CAD/CAE techniques to flowmeter modelling are eligible.
Design and development: the detailed design of the flowmeter head and/or signal processing aspects of novel flowmeters. Emphasis is given to papers identifying new sensor configurations, multisensor flow measurement systems, non-intrusive flow metering techniques and the application of microelectronic techniques in smart or intelligent systems.
Calibration techniques: including descriptions of new or existing calibration facilities and techniques, calibration data from different flowmeter types, and calibration intercomparison data from different laboratories.
Installation effect data: dealing with the effects of non-ideal flow conditions on flowmeters. Papers combining a theoretical understanding of flowmeter behaviour with experimental work are particularly welcome.