Patent ID: 12188410

DETAILED DESCRIPTION

FIG.1schematically illustrates a gas turbine engine20. The example gas turbine engine20is a turbofan that generally incorporates a fan section22, a compressor section24, a combustor section26and a turbine section28. The fan section22drives air along a bypass flow path B in a bypass duct defined within a nacelle30. The turbine engine20intakes air along a core flow path C into the compressor section24for compression and communication into the combustor section26. In the combustor section26, the compressed air is mixed with fuel from a fuel system32and ignited by igniter34to generate an exhaust gas flow that expands through the turbine section28and is exhausted through exhaust nozzle36. The fuel system32and the igniter34are mounted relative to an engine central longitudinal axis A. Although depicted as a turbofan turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines. As one example, rather than having the propulsor be an enclosed fan, the propulsor may be an open propeller.

As mentioned above, an engine such as engine20may be subject to icing conditions during use on an aircraft. The icing conditions could be a function of a current atmospheric state. As examples, outside air temperature, altitude, air pressure, etc. all contribute to creating potential icing conditions. Also the operational states of the gas turbine engine and the associated aircraft impact conditions. Examples of such operational states include if the aircraft is at cruise, takeoff, landing, etc.

When icing conditions are anticipated an aircraft pilot may take steps to mitigate the risks involved with accumulated ice. As mentioned above, some gas turbine engines may include anti-icing or de-icing equipment which may be operated to reduce ice accumulation.

While mitigating actions and anti-deicing equipment may reduce the risks associated with icing conditions they may also present undesirable limitations on the gas turbine engine operation, as well as reducing gas turbine engine efficiency and performance.

As such, Applicant has recognized that it may be desirable to be able to accurately determine whether a gas turbine engine and air inlet is or is not exposed to icing condition. With an accurate determination the gas turbine engine can be optimally operated during icing conditions and non-icing conditions.

FIG.2shows an air inlet to the engine20ofFIG.1. A strut48extends between an inner periphery of a core housing45and an inner housing46. A fluid conduit extends through the strut48, and has a first conduit52extending radially outwardly to a heat exchanger53positioned in the bypass duct128. An aircraft fluid, which may be oil at a relatively high temperature, is routed through conduit52, to the heat exchanger53, and then back through a second conduit50into the housing46. As can be appreciated, the strut48is exposed to inlet air flow C. A temperature sensor56is positioned at an upstream or radially outer position and a second temperature sensor54is positioned at a downstream radially inner location.

While the upstream location56is shown at the radially outer location, it should be understood that should the fluid be flowing radially outwardly the upstream location would be at the radially inner location. Moreover, while the temperature sensors are shown within a strut between a core engine outer housing and inner housing, the teachings of this disclosure could extend to fluids moving through the inlet air flow heading into the engine from any number of locations.

The strut48is positioned in a core inlet58between the core housing45and the inner housing46, but it could be positioned in other locations. Moreover, while oil is disclosed in this embodiment, other fluids may be utilized for the general teachings of this disclosure.

At any rate, a location receiving an aircraft fluid that is exposed to the inlet airflow is preferably utilized. Whatever temperature the air flow (here core air C, but again the temperature may be sensed elsewhere) may be at, it will generally cool the fluid within the conduit50between locations56and54. The temperature sensors54and56thus sense a temperature difference which is communicated to a control100.

The control100may be a standalone controller, or may be a full authority digital electronic controller for the overall engine (FADEC). In the exemplary example, the control100also controls a deicing system such as ports102which receive heated air as from a source106which taps air from the compressor section33of the gas turbine engine20.

The control100controls a valve104to selectively supply this air to ports102. While this particular deicing system is shown deicing the radially inner surface of a fan case105, there are a number of other deicing system which could be utilized within the broad teachings of this disclosure. This deicing system is illustrated merely for example.

Applicant has recognized the temperature differential between the sensors54and56will be a function of various atmospheric and gas turbine engine conditions including outside air temperature, air speed, fluid flow rate, fluid composition (e.g. oil, fuel, pressurized bleed air, etc.) and what condition the gas turbine engine may be at including idle, take off, cruise, etc. By accounting for the various atmospheric and gas turbine engine conditions a differential temperature threshold may be determined for the measured differential temperature of the fluid. The differential temperature threshold may correspond to a probability that icing conditions exist for the inlet at the current atmospheric and operational conditions.

The differential temperature threshold may be determined by analysis or testing of the gas turbine engine to determine differential temperature threshold. Look up tables may be developed for various atmospheric and gas turbine engine conditions. After determining differential temperature thresholds by test or analysis, the control100may be effectively programmed with information as shown in graphs likeFIGS.3and4.

As shown inFIG.3, the ambient temperature and calibrated air speed might be plotted with distinct slopes Y1and Y2which correspond to the main oil temperatures A and main oil temperature B. If the air speed is to the right of the slopes Y1or Y2then this is likely indicative of icing conditions. One then looks atFIG.4. If the delta temperature is above the slope Z, this is also indicative of an icing condition.

The main oil temperature is a temperature which is utilized by the engine control and provided to various control systems, and to the pilot, to provide an indication of the current temperature of the oil. While the location of the identified main oil temperature is not particularly controlling, for purposes of this disclosure, it is simply a reference temperature which may then be utilized to determine the likelihood of icing conditions.

FIG.4equates a delta temperature with the main oil temperature (“MOT”). On the slope Z, it can be seen that distinct main oil temperatures would have distinct expected delta temperatures associated with a risk of icing.

If an icing condition is identified, and exists for a predetermined minimum time, then an icing condition may be identified. If an icing condition is identified, the engine control may take one or more actions such as executing a pilot notification. Exemplary pilot notifications might include a warning light, an audible alarm, etc. Alternatively, or in combination, the anti-icing system might be actuated by the control.

FIG.5shows a block diagram for the method and control for which the control100is programmed.

Step200asks if the ambient temperature is below a set maximum temperature that is determined to be indicative of when icing conditions could occur. If so, at step202the calibrated air speed at an ambient temperature and MOT is determined. If the calibrated air speed is to the right of the slope (seeFIG.3), this is indicative of potential icing conditions.

At step204the control system will confirm icing conditions if the delta temperature is above a minimum threshold (FIG.4) and for more than a predetermined minimum amount of time step205.

At step206a cockpit notification might then occur. Alternatively, or in combination with step206an anti-icing measure could be automatically actuated at step208.

The controller is programmed to associate a plurality of main oil temperatures, and relative to an ambient temperature and a calibrated air speed, and identify the icing condition should the current calibrated air speed at a current main oil temperature be greater than an identified calibrated air speed that might indicative potential icing.

The control is also programmed to identify a particular temperature differential with a particular reference fluid temperature to identify whether the icing condition is occurring.

In a featured embodiment, a gas turbine engine20includes a propulsor24/26for providing air into a core engine housing, and for providing air as propulsion air radially outwardly of the core engine housing. The core engine housing surrounds a compressor section. A combustor is positioned downstream of the compressor section and a turbine section is positioned downstream of the combustor. An aircraft fluid moves within an inlet to the gas turbine engine, and is exposed to inlet air at the inlet. There is a first temperature sensor56for sensing a first temperature of the aircraft fluid at a first upstream point and a second temperature sensor54for sensing a second temperature of the aircraft fluid at a second downstream point where the aircraft fluid has been exposed to the inlet air for a period of time. A control100determines a temperature differential between first and second temperatures sensed by the first and second temperature sensors. The temperature differential is associated with a likelihood that an icing condition will occur, and the control is programmed to take a corrective action should an icing condition be identified.

In another embodiment according to the previous embodiment, a strut48extends between an outer engine core housing30and an inner engine core housing46and the aircraft fluid passes through the strut.

In another embodiment according to any of the previous embodiments, the aircraft fluid is oil being routed through the strut to a heat exchanger53.

In another embodiment according to any of the previous embodiments, a fan case22surrounds the propulsor, and the propulsor is a fan rotor. The fan rotor delivers air into a bypass duct defined between the fan case and the outer core engine housing, and the heat exchanger is positioned in the bypass duct.

In another embodiment according to any of the previous embodiments, the control100is programmed to identify a particular temperature differential with a particular reference fluid temperature to identify whether the icing condition is occurring.

In another embodiment according to any of the previous embodiments, the control100is programmed to identify the icing condition should the temperature differential continue to suggest an icing condition for a minimum period of time.

In another embodiment according to any of the previous embodiments, the aircraft fluid is oil, and the reference fluid temperature is a main oil temperature utilized by the control100.

In another embodiment according to any of the previous embodiments, the controller100is also programmed to associate a plurality of main oil temperatures, and relative to an ambient temperature and a calibrated air speed, and identify the icing condition should the current calibrated air speed at a current main oil temperature be greater than an identified calibrated air speed that might indicative potential icing.

In another embodiment according to any of the previous embodiments, the aircraft fluid is oil being routed through the strut to a heat exchanger.

In another embodiment according to any of the previous embodiments, the control is programmed to identify the icing condition should the temperature differential continue to suggest an icing condition for a minimum period of time.

In another featured embodiment, a method of operating a gas turbine engine includes the steps of providing air from a propulsor into a core engine housing, and as propulsion air radially outwardly of the core engine housing. An aircraft fluid is moved within an inlet to the gas turbine engine, and exposed to inlet air32. The method then senses a first upstream temperature56of the aircraft fluid and a second downstream temperature54after the aircraft fluid has been exposed to the inlet air for a period of time. A temperature differential is determined between the first and second temperatures. The temperature differential is associated with a likelihood that an icing condition will occur, and a corrective action is taken should an icing condition be identified.

In another embodiment according to any of the previous embodiments, a strut48extends between an outer engine core housing30and an inner engine core housing46and the aircraft fluid passing through the strut.

In another embodiment according to any of the previous embodiments, the aircraft fluid is oil routed through the strut to a heat exchanger53.

In another embodiment according to any of the previous embodiments, a fan case22surrounds a fan rotor, and the propulsion air delivered by the fan rotor is delivered into a bypass duct128defined between the fan case and an outer core engine housing, and the heat exchanger53being positioned in the bypass duct.

In another embodiment according to any of the previous embodiments, a control100is programmed to identify a particular temperature differential with a particular reference fluid temperature to identify whether the icing condition is occurring.

In another embodiment according to any of the previous embodiments, the control100identifying the icing condition should the temperature differential continue to suggest an icing condition for a minimum period of time.

In another embodiment according to any of the previous embodiments, the aircraft fluid is oil, and the reference fluid temperature is a main oil temperature utilized by the control100.

In another embodiment according to any of the previous embodiments, the controller100is also programmed to associate a plurality of main oil temperatures, and relative to an ambient temperature and a calibrated air speed, and identify the icing condition should the current calibrated air speed at a current main oil temperature be greater than an identified calibrated air speed that might indicative potential icing.

In another embodiment according to any of the previous embodiments, the aircraft fluid is oil routed through the strut to a heat exchanger53.

In another embodiment according to any of the previous embodiments, the control identifying the icing condition should the temperature differential continue to suggest an icing condition for a minimum period of time.

Although embodiments have been disclosed, a worker of ordinary skill in this art would recognize that modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the true scope and content of this disclosure.