Atmospheric Liquid Water Content Measurement and Calibration System.
Abstract
An object of the invention is to provide a satisfactory system of liquid water measurement primarily for stationary and possibly adaptable for aircraft borne measurements. A feature of the invention relates to a single grid differential system. Summarized most simply, this system is a combination of two techniques which are used together, effectively combining their features. One technique is an absolute measurement based on mass accumulation rate and used primarily for calibration purposes. The mass accumulation rate on a filter, when divided by the flow rate of the medium through this apparatus, yields the total droplet mass density. The second technique is a differential measurement with two adjacent sampling inlets, one is unrestricted while the other is inertially filtered to eliminate water droplets. The two flow streams in the differential system are cyclically sampled and the combined flow passes a heated wire grid designed to evaporate droplets encountered. The resulting oscillating signal (with DC component) is fed into a lock-in amplifier whose output is the rms value of the difference signal. The vapor component is thereby subtracted and the signal is processed by the phase-locked signal-to-reference detection technique which produces very high sensitivity by virtue of minimizing the noise bandwidth.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 1981
- Accession Number
- ADD009256
Entities
People
- Charles W. Bruce
- Ralph J. Brewer
Organizations
- United States Army