Patent Application
20140169401
The present invention relates to an air temperature sensor arrangement for a vehicle and a method of measuring air temperature proximate a vehicle.
Vehicles often include external air temperature measurement devices that provide useful information to an operator of the vehicle. An aircraft is an example of a vehicle that employs such devices, based on the benefits of accurate exterior air temperature knowledge. The temperature measurement devices directly provide the air temperature and additional data may be obtained inferentially from that information, such as a true airspeed of the aircraft.
Unfortunately, uncertainty of temperature readings is often observed due to a number of sources, including various flight conditions. One major error source arises from uncertainty in non-adiabatic heating of the measured air when performing deicing, referred to as deicing heating error (DHE). DHE can increase when icing of the sensor occurs, since traditional sensors regularly ice in extreme environmental conditions.
According to one embodiment, an air temperature sensor arrangement for a vehicle includes a temperature sensor housing having a base portion, an inlet and an outlet. Also included is a main flow path defined by a continuously curvilinear wall, the main flow path extending from the inlet to the outlet for separating particulate matter from an inlet airflow. Further included is a temperature sensor disposed within an internal cavity of the temperature sensor housing.
According to another embodiment, a method for measuring air temperature proximate a vehicle is provided. The method includes ingesting a main flow into an inlet of a temperature sensor housing. Also included is flowing the main flow through a main flow path defined by a continuously curvilinear wall. Further included is separating particulate matter from an inlet airflow as the main flow passes through the main flow path. Yet further included is expelling particulate matter from the temperature sensor housing through an outlet. Also included is measuring a temperature of the inlet airflow with a temperature sensor disposed in a cavity at an internal location of the temperature sensor housing.
The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
Referring to
An air temperature sensor arrangement 30 is illustrated as disposed proximate a surface of the nose section 10 of the aircraft 4, however, the air temperature sensor arrangement 30 may be employed at various other locations of the aircraft 4, such as proximate other areas of the fuselage 7, the tail section 12 or an engine (not illustrated), for example. The air temperature sensor arrangement 30 is configured to measure a total air temperature. Total air temperature refers to a measurement of the temperature of air at a stagnation point of air that is at rest relative to the aircraft 4. As the air is brought to rest, kinetic energy is converted to internal energy. The air is compressed and experiences an adiabatic increase in temperature. Therefore total air temperature is higher than the static (or ambient) air temperature and is a useful input to an air data computer in order to enable computation of static air temperature and hence true airspeed.
Referring now to
The cavity inlet 46 is located along the main flow path 44 in a radial direction between the inlet 36 of the temperature sensor housing 32 and an outlet 52 of the temperature sensor housing 32. In other words, the cavity inlet 46 is disposed downstream of the inlet 36 and upstream of the outlet 52, relative to the predominant flow direction of the main flow 38. It is proximate the location along the main flow path 44 at the cavity inlet 46 that the main flow 38 is substantially separated into the inlet airflow 40 and the particulate matter 42. The inlet airflow 40 is routed into the cavity inlet 46 into the cavity 48 for temperature measurement by the temperature sensor 50 located therein. The particulate matter 42 separated from the inlet airflow 40 continues along the main flow path 44 and is expelled from the temperature sensor housing 32 through the outlet 52.
Separation of the main flow 38 into the inlet airflow 40 and the particulate matter 42 is achieved by the geometry of the main flow path 44. The main flow path 44 is defined by a continuously curvilinear wall 54 that extends from the inlet 36 to the outlet 52, with an interruption only at the cavity inlet 46. The continuously curvilinear wall 54 is contoured to reduce boundary layer formation along the continuously curvilinear wall 54 and to avoid recirculation of the main flow 38 along the main flow path 44. The continuously curvilinear wall 54 may be contoured in numerous alternative geometries, but typically a substantially circular or elliptical cross-section is employed to account for varying incoming orientations of the main flow 38, as opposed to the inclusion of planar portions along the main flow path 44. As shown, the main flow path 44 typically funnels or tapers from a larger cross-sectional area at the inlet 36 to a smaller cross-sectional area at the outlet 52. At least one portion of the main flow path 44, such as proximate the inlet 36, may be symmetric about an axis 56. Such a portion may be located proximate the inlet 36, the outlet 52, or both. It is to be understood that the inlet 36 may be formed of various cross-sectional geometries, including circular or elliptical, for example, but these exemplary geometries noted are not intended to be limiting.
A method 100 for measuring air temperature proximate a vehicle 2 is also provided as illustrated in
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
