Gas turbine engines often operate in an atmosphere that has a low temperature, below freezing. As a result, pneumatic parts of the engines that have moist air are likely to freeze if steps aren't taken to prevent freezing.
For example, the burner pressure sense line runs from a diffuser case port or burner pressure source to a remote sensor location such as the electronic engine control (EEC) housing. Blockages anywhere in this pneumatic sensing system can result in an erroneous burner pressure signal, which is used to control engine thrust. In some cases, this results in a loss of thrust control which may be a significant safety issue. One common cause of pneumatic sense line blockage is the accumulation of moisture in the presence of freezing ambient conditions. This results in blockage of burner pressure passages, preventing the burner pressure signal from reaching the sensor's diaphragm.
Prior art methods have used water traps and weep holes to remove moisture, but have not been completely successful. Many burner pressure sensing systems include screens to protect the sensor from Foreign Object Damage (FOD) and contaminates in the burner pressure air. However, the screens themselves can become a collection point for moisture preventing it from draining out of the EEC.
While efforts are made to remove moisture from the pneumatic sense line, those efforts are not always successful and moisture does reach the sensors.
Some turbofan jet engines utilize burner pressure smart transducers to monitor the pressure in the burner. In flight as noted above, these transducers are exposed to freezing temperatures. These cold temperatures cause air moisture to condense inside the sensor. The condensate can freeze, causing an obstruction of the interior passages that will prevent the sensor's diaphragm from sensing pressure changes.
Currently a heater is utilized on or in the pneumatic sensor. Tests have shown, however, that the heater is inefficient at providing heat where is needed to prevent freezing at the sensor's sensing system. It also does not significantly reduce air moisture condensation.
USPTO Backgrounds
USPTO Backgrounds