The calibration of and measurements with cylindrical hot-film probes in water flows

Abstract

This paper describes an integrated experimental procedure for obtaining accurate measurements with both single normal (SN) and X hot-film probes in water flows. The first pari of the paper describes techniques developed to overcome the common problems of temperature variations and contamination in a recirculating test facility, leading to long-term calibration stability. The second part of the paper describes the development of fast, reliable and accurate computer-based calibration methods for both SN and X probes. The final section of the paper describes comparative measurements between an SN and an X probe in vertical upward water pipe flow, demonstrating the validity of the methods developed.

Experimental study of kerosene–water two‐phase flow in a vertical pipe using hot‐film and dual optical probes

“…The instruments used in this study included the hot‐film and optical probes. The hot‐film technique was studied by Farrar and Bruun (1989), Samways et al (1994), Farrar et al (1995) and Hamad and Bruun (2000) to understand the drop–probe interaction, calibration and signal analysis for calculating water velocity, turbulence intensity and volume fraction. Hamad et al (1997, 2000) investigated the application of an optical probe for liquid–liquid flow.…”

“…The pioneering works on liquid–liquid two‐phase flow were published by the research group at University of Bradford (Farrar and Bruun, 1989; Samways et al, 1994; Farrar et al, 1995; Farrar and Bruun, 1996; Al‐Deen and Bruun, 1997; Hamad et al, 1997, 2000; Hamad and Bruun, 2000). Most of these papers concentrated on the development of hot‐film and dual optical techniques for kerosene–water upward flow in a 77.7 mm inner diameter acrylic vertical pipe.…”

Shock wave in a bubble flow with high gas content

“…Second, the film sensor has a quartz coating which prevents the formation of bubbles on its surface due to heating [6]. Third, the film sensor is recomended to make measurements in two-phase flows in a number of papers [7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Fourth, the substrate heating losses of the film sensor in water can be neglected [11].…”

“…King's law [21] is used in our work as a law connecting the flow rate with the energy spent on heating the film. Using [7][8][9][10][11][12][13][14][15][16][17][18][19][20]22], King's law for a supersonic microbubble-fluid flow is written as…”

“…where E is the voltage on the thermoanemometr probe, A and B are calibration constants, ρ is the mixture density, V the mixture velocity. Following [10,11] the typical sensor overheating is given as 1.08. The unclosed system of fixed-temperature water supply is used to prevent the temperature fluctuations during the experiment.…”