Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Patent
1995-04-05
1997-04-15
Wieder, Kenneth A.
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
364550, G01R 2702
Patent
active
056213328
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a device and method for the non-intrusive and spatial interrogation of substances to identify and quantify the substances from measurements dictated by the dielectric profile of the substances. In particular, this invention relates to a device and method of detecting an accumulation of air, water, ice, snow or variety of possible contaminants such as de-icing fluid on aircraft surfaces.
BACKGROUND OF INVENTION
Ice accumulation on aircraft surfaces has been a problem since the inception of the aviation industry. The accumulation of ice has four main effects which are all negative and in some instances catastrophic. First, aerodynamic performance is severely restricted resulting in a loss of lift and increase drag. Second, the accumulation of ice increases the aircraft weight. Third, the accumulation of ice will impair or restrict the movement of control surfaces. Fourth, the ice may be ingested into the engine or other system intakes terminating engine operation.
Recently, interest in aircraft icing has been greatly heightened with an increase in industry and public awareness of the hazards associated with this problem. Although the detrimental effects of ice build up on aircraft performance has been generally well acknowledged, difficulties in predicting or measuring ice accumulation on aircraft has prevented rigorous and reliable procedures for flight crews both on the ground and in the air to minimize this problem.
The problem of aircraft icing occurs in two broad categories. First, inflight icing occurs on the leading edge of the airfoil. This type of ice build up is common and is handled by pilot observations or pilot awareness or suspicions of impending icing conditions. In many aircraft, the leading edges of the wing are heated by engine bleed air at temperatures of up to 250.degree. C. Engine air bleed is normally done at regular intervals when icing conditions are likely regardless as to whether any ice has accumulated. A percentage of engine air is required to be used to heat the aircraft wing rather than for propulsion purposes. It is very inefficient to bleed engine air when no ice has accumulated on the aircraft surface.
The second category of aircraft icing is ground icing. Ground icing occurs over the top of the aircraft surface when the aircraft is standing. Icing on the leading 10% of the wing has the most critical aerodynamic effect. This type of ice accumulation is handled by the application of de-icing or anti-icing fluids. The problem is amplified since de-icing depends not only on how well the de-icing was undertaken but also whether ice has re-accumulated since de-icing.
On current commercial aircraft, pilots have no reliable way of judging the amount of ice accumulated on the surface of the aircraft both inflight and on the ground. Further, pilots have no means of assessing the status of the de-icing or anti-icing fluids which may have been applied in accordance with current flight procedures. Pilots are accordingly faced with difficult decisions on a regular basis in order to maintain flight schedules.
Several devices have been proposed which are designed to detect the presence of ice which has accumulated on the aircraft surface. One such device will vibrate an aircraft surface at a known frequency. When the aircraft surface vibrates at a different frequency, the presence of ice has been detected.
Still other devices have been proposed which detect the presence and thickness of ice on an aircraft surface. Such devices have been described in detail in U.S. Pat. No. 4,766,369, Weinstein. This device uses two capacitive gauges and a temperature gauge. The ratio of the voltages of sense side of the capacitive gauges determines the thickness of the ice present.
Although, these devices may detect the presence of ice on an aircraft surface it cannot detect the presence of substances other than ice such as snow, slush, de-icing fluid or din. In fact, there are no known devices which can detect the presence of snow on an aircraft surface.
REFERENCES:
patent: 4628736 (1986-12-01), Kirby et al.
patent: 5394340 (1995-02-01), Inkpen et al.
Measurement of Spatial Variations in Electrical Properties of Model Ice, Cold Regions Science and Technology, 16 (1989) 201-209 (Month Unavailable).
Laboratory Evaluation of a Sensor for Detection of Aircraft Wing Contaminants, 30th Aerospace Sciences, Jan. 6-0, 1992, Reno, NV, pp. 1-9.
Development of a Sensor for the Detection of Aircraft Wing Contaminants, 30th Aerospace Sciences, Jan. 6-9, 1992, Reno, NV, pp. 1-6.
An Objective Method for Measuring Surface Ice Accretion, Paul Tattelman, Apr., 1982, Air Force Geophysics Lab, Hanscom AFB, MA, pp. 599-610.
Model Approach to Obtaining Continuum Properties from Inter-Digital Electrode Dielectrometry, Mass. Institute of Technology, Jul. 1986, M. Zaretsky et al, p. 0-45.
Generation of an Aircraft Ice Sensor Data Base and Evaluation of De/Anti-Icing Fluids, Instrumar Limited, Sep., 1993, Chris Nolan et al, vol. 1 and Appendix B and C.
Evaluation of flight Crew Requirements and Human Factors Related to a Cockpit Display of Aircraft Surfaces During Periods of Freezing Precipitation, Final Report, Instrumar Limited, 12 Dec. 1994, vol. 1 and 2.
Laboratory and Field Testing of De/Anti-Icing Technologies, Instruman Limited, Feb., 1995, vol. 1.
Hall John
Inkpen Stuart
Marshall Chris
Nolan Chris
Bowser Barry C.
Wieder Kenneth A.
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