Hot-film/hot-wire anemometer calibration for low velocities using image processing

Document Type : Article


Department of Aerospace, Faculty of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran.


Calibration of hot-wire and hot-film probes at low velocities is a difficult task because the dynamic pressure at these velocities is very low and may not be measured easily. To overcome this problem, substituent techniques have been presented in the literature that rely on other phenomena and utilize different hardware. This paper describes a simple and low-cost method which proposes to move the anemometer probe in quiescent air (here by means of a swinging arm) and track this motion with a camera. After processing of the images, velocity time history of the probe is found by numerical calculations. Calibration curve is then obtained without any predetermined relationship. Using a medium-speed video camera that is often found in laboratories would avoid the need to a position sensor and a complicated arm on which this sensor is mounted. This technique can be used not only for pendulums but also for other means of moving probes in quiescent medium.


1. Davari, A.R., Soltani, M.R., and Ghaeminasab, M. "The unsteady behavior of subsonic wind tunnel wall pressure during pitching motion of the model", Scientia Iranica, 21(1), pp. 192-202 (2014).
2. Davari, A.R., HadiDoolabi, M., Soltani, M.R., Soltani, M.R., and Izadkhah, M. "Aspects of canard-wing vortices interaction in subsonic flow", Scientia Iranica, 22(3), pp. 743-754 (2015).
3. Soltani, M.R., Askari, F., and Sadri, V. "Roughness and turbulence e ects on the aerodynamic efficiency of a wind turbine blade section", Scientia Iranica, 23(3), pp. 927-941 (2016).
4. Barratt, D., Nguepnang, M.A., and Atkins, M.D. "Fast-response velocity and shear stress measurements", In Application of Thermo-Fluidic Measurement Techniques: An introduction, Kim T., Lu T.J., and Song S.J, pp. 101-123, Butterworth-Heinemann, Oxford, UK (2016).
5. Berdanier, R.A. and Key, N.L. "A novel data reduction technique for single slanted hot-wire measurements used to study incompressible coflmpressor tip leakage flows", Exp. Fluids, 57(29), pp. 1-4 (2016).
6. Milavec, M., Sirok, B., Vidal, D., and Hocevar, M."Identication of noise generation and ow kinematics in the air gap for two di erent blade tip designs of an axial fan", Forsch. Ingenieurwes, 79(1), pp. 29-39 (2015).
7. Pezzotti, S., D'Iorio, J.I., Nadal-Mora, V., and Pesarini, A. "A wind tunnel for anemometer calibration in the range of 0.2-1.25 m/s", Flow Meas. Instrum., 22(4), pp. 338-342 (2011).
8. Lecic, M.R. "A new experimental approach to the calibration of hot-wire probes", Flow Meas. Instrum., 20(3), pp. 136-140 (2009).
9. Grandchamp, X., Van Hirtum, A., and Pelorson, X. "Hot lm/wire calibration for low to moderate flow velocities", Meas. Sci. Technol., 21(11), p. 115402 (2010).
10. Ardekani, M.A. "Hot-wire calibration using vortex shedding", Measurement, 42(5), pp. 722-729 (2009).
11. Sattarzadeh, S.S., Kalpakli, A., and Orlu, R. "Hot- wire calibration at low velocities: Revisiting the vortex shedding method", Adv. Mech. Eng., p. 241726 (2013).
12. Lee, T. and Budwig, R. "Two improved methods for low-speed hot-wire calibration", Meas. Sci. Technol., 2(7), pp. 643-646 (1991).
13. Yue, Z. and Malmstrom, G. "A simple method for low- speed hot-wire anemometer calibration", Meas. Sci. Technol., 9(9), pp. 1506-1510 (1998).
14. Piccato, A., Malvano, R., and Spazzini, P.G. "Metro-logical features of the rotating low-speed anemometer calibration facility at INRIM", Metrologia, 47(1), pp. 47-57 (2010).
15. Spazzini, P.G., Piccato, A., and Malvano, R. "Metro-logical features of the linear low-speed anemometer calibration facility at INRIM", Metrologia, 46(1), pp. 109-118 (2009).
16. Chua, L.P., Li, H.-S., and Zhang, H. "Calibration of hot wire for low speed measurements", Int. Commun.Heat Mass Transf., 27(4), pp. 507-516 (2000).
17. Bruun, H.H., Farrar, B., and Watson, I. "A swinging arm calibration method for low velocity hot-wire probe calibration", Exp. Fluids, 7(6), pp. 400-404 (1989).
18. Guellouz, M.S. and Tavoularis, S. "A simple pendulum technique for the calibration of hot-wire anemometers over low-velocity ranges", Exp. Fluids, 18(3), pp. 199- 203 (1995).
19. Ozahi E., C arpinlioglu, M. O., and Gundogdu, M.Y. "Simple methods for low speed calibration of hot-wire anemometers", Flow Meas. Instrum., 21(2), pp. 166- 170 (2010).
20. Krause, M., Gaisbauer, U., Kraemer, E., and Kosinov, A.D. "Implementation of a new thermal model and static calibration of a wedge-shaped hot- lm probe in a constant-temperature mode", Int. J. Heat Mass Transf., 126(A), pp. 1-9 (2018).
21. Liu, X., Li, Z., and Gao, N. "An improved wall shear stress measurement technique using sandwiched hotlm sensors", Theor. Appl. Mech. Lett., 8(2), pp. 137- 141 (2018).
22. Kaiser, E. "Increase factor for forced convection at small heating elements", Forsch. Ingenieurwes., 82(1), pp. 9-20 (2018), (in German).
23. Miheev, N.I., Molochnikov, V.M., Kratirov, D.V., Hayrnasov, K.R., and Zanko, P.S. "Hot-wire measurements with automatic compensation of ambient temperature changes", Therm. Sci., 19(2), pp. 509- 520 (2015).
24. Johansson, A.V. and Alfredsson, P.H. "On the structure of turbulent channel flow", J. Fluid Mech., 122(1), pp. 295-314 (1982).
25. Moravec, J. and Hub, M. "Automatic correction of barrel distorted images using a cascaded evolutionary estimator", Inform. Sciences, 366(1), pp. 70-98 (2016).
26. Ikeya, Y., Orlu, R., Fukagata, K., and Alfredsson, P.H. "Towards a theoretical model of heat transfer for hot wire anemometry close to solid walls", Int. J. Heat Fluid Flow, 68(1), pp. 248-256 (2017).
27. Sun, B., Ma, B., Luo, J., Li, B., Jiang, C., and Deng, J. "Sensing elements space design of hotlm sensor array considering thermal crosstalk", Sensor. Actuat. A-Phys., 265(1), pp. 217-223 (2017).