Thermal measuring and testing – Temperature measurement – With fluid flow deflector
Reexamination Certificate
2000-05-24
2001-06-26
Bennett, G. Bradley (Department: 2859)
Thermal measuring and testing
Temperature measurement
With fluid flow deflector
Reexamination Certificate
active
06250801
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a probe for measuring physical parameters of a flow of fluid.
The invention has a particularly advantageous application in the field of aeronautics, for measuring the temperature of air flowing around an aircraft fuselage or entering the compressor stage of an aircraft jet engine.
BACKGROUND OF THE RELATED ART
Probes mounted on the wall of the fuselage or the engine air intake of an aircraft to measure air temperature are known in the art. Such probes are designed to operate in environments and at altitudes where the temperatures are much lower than 0° C. and in atmospheres that may be charged with supercooled water molecules.
A constraint inherent to the operation of such probes is that they must include means to prevent the formation and accumulation of ice in the proximity of the sensitive element of the probe. Indeed, such an ice accumulation would falsify the measurements effected by the probe.
A prior art solution to the problem of preventing the accumulation of ice consists in heating parts of the probe in the proximity of the sensitive element and in correcting the systematic measurement error due to such heating
Such a solution is generally acceptable for measuring the temperature in environments containing relatively little supercooled water (for example less than 1.25 g of supercooled water per m
3
of air), but is not suitable in itself for de-icing the probe correctly in atmospheres with a higher moisture content.
This is because, in this case, the only way to guarantee that the ice will melt is more intensive heating, but melting the ice causes a flow of water droplets which come into contact with the sensitive element as they flow over it and thereby falsify the measurements effected by the probe.
Also, more intense heating is not an economically viable solution because of the non-negligible increased electrical power consumption and the associated cost.
Another way to de-ice the probe, used in conjunction with heating, is to define the geometry of the probe to maximize deflection of the trajectories of supercooled water particles contained in the flow of air around the probe so that a high proportion of the particles are kept away from the sensitive element of the probe.
Thus probes exist in which the sensitive element is accommodated in an internal passage which only some of the water particles enter when the air flows around the probe. However, that solution has the drawback of complicating manufacture of the probe, as it is then necessary to provide complex arrangements for connecting electrical cables to supply power to the sensitive element and collect the signals it delivers.
Moreover, in that case, the sensitive element S in a passage into which only part of the air flow enters, and is therefore ventilated only slightly by the airflow, which means that it must be of high sensitivity, which generally increases its cost and makes it more fragile (through the use of ceramic temperature-measuring components, for example).
Another prior art probe has an airfoil profile with the sensitive element in a duct passing obliquely through the thickness of the profile. The sensitive element in that probe is located in a flow that is secondary to the main flow of air around the probe, said secondary flow conveying significantly fewer water particles than the main flow. With only moderate heating of the probe, it is possible to measure reliably the temperature of environments with a relatively high moisture content and at relatively low temperatures.
SUMMARY
An object of the invention is to effect a significant further improvement over the prior art referred to above to enable probes to be made that are able to operate over wider ranges of temperature and moisture content, and where the manufacture and operating costs of the probe are reduced and its reliability is increased
To achieve the above object, the invention proposes a probe comprising a structure carrying at least one sensor for measuring physical parameters of a flow of fluid directed generally towards the rear of the probe, which probe is characterized in that said structure has a part with a leading edge which is generally in front of the sensor and is of a shape adapted to create a vortex, and in that the sensor is in the axial region of said vortex.
Preferred, but non-limiting, features of the probe according to the invention are as follows:
said structural part shelters said vortex from the flow of the fluid;
said sensor is a temperature sensor comprising a thermocouple or a positive temperature coefficient resistor, in particular of platinum;
said structural part is adapted to be mounted with a non-zero angle of incidence to the main direction of flow of the fluid to define a lower surface and an upper surface of said structural part;
said non-zero angle of incidence is in the range 15° to 45° and is preferably approximately 30°;
said structural part has the general shape of half a delta wing;
said half delta wing has a sweep angle in the range 35° to 65° and preferably approximately 50°;
said structural part is essentially plane;
said structural part has a tapered region between its lower surface and its leading edge so that said leading edge is sharp;
said sensor extends in an essentially straight line in the vicinity of the upper surface of said structural part and defines a first angular offset to the upper surface, the projection of the sensor onto the mean plane of the upper surface defining in that plane a second angular offset to the leading edge of the structural part;
each of said angular offsets has a value in the range 5° to 20°;
said structural part incorporates heater means;
said structural part incorporates two plates respectively corresponding to the lower surface and the upper surface and with resistive wires between them constituting said heater means and the gap between the two plates is filled with brazing alloy;
the thermal conductivity of the plate corresponding to the lower surface of said structural part is higher than that of the plate corresponding to its upper surface; and
said structural part is mounted on a streamlined pylon.
REFERENCES:
patent: 2579271 (1951-12-01), Polye
patent: 2588840 (1952-03-01), Howland
patent: 2970475 (1961-02-01), Werner
patent: 3016745 (1962-01-01), Simon
patent: 4152938 (1979-05-01), Danninger
patent: 4595298 (1986-06-01), Frederick
patent: 4765751 (1988-08-01), Pannone et al.
patent: 4821566 (1989-04-01), Johnston et al.
patent: 5035514 (1991-07-01), Newman
patent: 5356219 (1994-10-01), Tammera et al.
patent: 5544526 (1996-08-01), Baltins et al.
patent: 5628565 (1997-05-01), Hagen et al.
patent: 5653538 (1997-08-01), Phillips
patent: 6076963 (2000-06-01), Menzies et al.
patent: 0835804 (1997-08-01), None
Auxitrol S.A.
Bennett G. Bradley
Blakely & Sokoloff, Taylor & Zafman
Verbitsky Gail
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