Modares Mechanical Engineering

Modares Mechanical Engineering

Experimental Investigation of Strength of Vortex Shedding from a Semicircular Cylinder Dual Bluff Body

Document Type : Original Research

Authors
Ehsan Ardekani
Mohammad Ali Ardekani
Foad Farhani
Iranian Research Organization for Science and Technology (IROST)
10.48311/mme.25.1.33
Abstract
One of the methods to improve the performance of the vortex flowmeter, especially for low flowrate, is to use a dual bluff model that increases the vortex shedding frequency. In this experimental research work, the vortex shedding from a dual cylindrical bluff model of semicircular cross-section, at different l d ratios, where d is the diameter and l is the distance between the two semicircular cylinders in series is measured and investigated using a wind tunnel and hot-wire anemometer. Results show that the Strouhal number for dual bluff body depends on the Reynolds number and l d . In the range of 0/8≤ l d <2 , the Strouhal number has changes and jumps compared to the Reynolds number. Therefore, it is not suitable for vortex flowmeter application. also show that the velocity frequency spectrum, it can be determined that the highest value of the turbulent intensity is related to the oscillating velocity with the vortex shedding frequency, and therefore, to investigate the strength of vortex shedding frequency, the turbulent intensity was investigated, that the value of turbulent intensity depends on Reynolds number and l d . Considering the standard deviation of the repeatability of the Strouhal number reading and also the strength of the vortex shedding frequency (investigation of the turbulent intensity), for 0< l d <0/8 and 2≤ l d ≤3 , a dual cylindrical bluff model of semicircular cross-section, placed in series, is suitable for vortex flowmeter application
Keywords
Dual Bluff Body
Reynolds number
Strouhal number
Turbulent Intensity
Vortex Flowmeter
Vortex Shedding

Subjects

1. Roshko, A., On the wake and drag of bluff bodies. Journal of the aeronautical sciences, 1955. 22(2): p. 124-132.
2. 2. Venugopal, A, A. Agrawal, and S.V. Prabhu, Review on vortex Flowmeter-Designer perspective. Sensors and Actuators A: Physical, 2011: p. 8-23.
3. Sun, Z, H. Zhang, and J. Hou, Evaluation of uncertainty in a vortex flowmeter measurement. Measurement, 2008: p. 349-356.
4. Thinh, N. and J. Evangelisti. Flow modeling and experimental investigation of a vortex shedding flow meter. in ASME FEDSM. 1997.
5. Bentley, J. and J. Mudd, Vortex shedding mechanisms in single and dual bluff bodies. Flow Measurement and instrumentation, 2003. 14(1-2): p. 23-31.
6. Peng, J., X. Fu, and Y. Chen, Flow measurement by a new type vortex flowmeter of dual triangulate bluff body. Sensors and Actuators A: Physical, 2004. 115(1): p. 53-59.
7. Peng, J. and M. Fang, Response of a dual triangulate bluff body vortex flowmeter to oscillatory flow. Flow measurement and instrumentation, 2014. 35: p. 16-27.
8. HONDA, S. and H. YAMASAKI, Stabilization of Vortex Shedding in a Three-Dimensional Flow in a Circular Pipe. Transactions of the Society of Instrument and Control Engineers, 1981. 17(7): p. 764-769.
9. Igarashi, T., Flow characteristics around a circular cylinder with a slit: 1st report, flow control and flow patterns. Bulletin of JSME, 1978. 21(154): p. 656-664.
10. Igarashi, T., Characteristics of the flow around two circular cylinders arranged in tandem: 1st report. Bulletin of JSME, 1981. 24(188): p. 323-331.
11. IGARASHI, T., Flow characteristics around a circular cylinder with a slit: 2nd report, effect of boundary layer suction. Bulletin of JSME, 1982. 25(207): p. 1389-1397.
12. Bentley, J. and R. Benson, Design conditions for optimal dual bluff body vortex flowmeters. Flow Measurement and Instrumentation, 1993. 4(4): p. 205-213.
13. Bentley, J., R. Benson, and A. Shanks, The development of dual bluff body vortex flowmeters. Flow Measurement and instrumentation, 1996. 7(2): p. 85-90.
14. Fu, X and Yang, H, Study on hydrodynamic vibration in dual bluff body vortex flowmeter. Chin. J. Chem., 2001. 9(2): p. 123-128.
15. Forouzi Feshalami, B., et al., A review of experiments on stationary bluff body wakes. Physics of Fluids, 2022. 34(1).
16. Jørgensen, F.E., How to measure turbulence with hot-wire anemometers: a practical guide. 2001: Dantec dynamics.
17. Ardekani, M., F. Farhani, and A. Nourmohammadi, Experimental study of drag coefficient of multistrand wires using single normal hot-wire anemometer probe. Flow Measurement and Instrumentation, 2016. 50: p. 237-244.
18. Ardekani, M. and F. Farhani, Experimental study on response of hot wire and cylindrical hot film anemometers operating under varying fluid temperatures. Flow Measurement and Instrumentation, 2009. 20(4-5): p. 174-179.
19. Ardekani, M., Hot-wire calibration using vortex shedding. Measurement, 2009. 42(5): p. 722-729.
20. Ardekani, E., F. Farhani, and M.A. Ardekani, Determination of flow angle from measurements of vortex shedding frequency downstream of a triangular bluff model using a single sensor hot-wire probe. Flow Measurement and Instrumentation, 2024. 100: p. 102731.
21. Xu, S., et al., Experimental study of flow around polygonal cylinders. Journal of fluid mechanics, 2017. 812: p. 251-278.
22. Ardekani, E., F. Farhani, and M.A. Ardakani, Experimental Investigation of the Frequency Spectra of Vortex Shedding from a Triangular Bluff Body at Different Flow Angles. Amirkabir Journal of Mechanical Engineering, 2024. 56(5): p. 3-3.
Modares Mechanical Engineering
Volume 25, Issue 1
January 2024
Pages 33-41