Determination of Medium Volume Diameter (MVD) and Liquid Water Content(LWC) by Multiple Rotating Cylinders

This paper reports on an investigation into use of multiple rotating cylinders for measuring liquid water content (LWC) and median volume diameter (MVD) of the spray cloud in icing wind tunnels. The apparatus, as well as measurement and data-reduction procedures are described. The rotating multiple cylinder technique has been tested in an icing wind tunnel together with other instruments. Results for LWC agree with those from an icing blade and a single rotating cylinder within the uncertainty range of about ±5 percent for all three instruments. Comparison of results for MVD with those from two different optical droplet sizing instruments indicates that the multiple rotating cylinder technique yields MVD values within about ±10 percent of the true values, at least for LWC and MVD ranging from about 0.5 to 2 g/m3 and 10 to 45 :m, respectively. These results indicate that the multiple rotating cylinder technique could provide an excellent and cost-effective standard for checking the calibration of heated sensor LWC probes and of optical droplet sizing instrumentation.