Liquid fluid systems for turbine engines

A pericritical fluid system for a thermal management system associated with a turbine engine, the pericritical fluid system comprising:

• a cooling circuit configured to circulate a pericritical fluid;
• a phase detection sensor configured to generate a sensor output including an impedance value corresponding to the pericritical fluid;
• and
• a controller communicatively coupled to the phase detection sensor, the controller configured to:
• determine that the pericritical fluid has reached a bubble point based at least on a first characteristic change in the impedance value;
• determine that the pericritical fluid has reached a dew point based at least on a second characteristic change in the impedance value, the second characteristic change being different from the first characteristic change;
• and
• control at least one controllable component of the thermal management system based at least on the bubble point and the dew point.

A non-transitory computer-readable medium storing instructions that, when executed by one or more processors of a controller for a thermal management system associated with a turbine engine, cause the controller to:

• receive a sensor output from a phase detection sensor in fluid communication with a pericritical fluid circulating through a cooling circuit, the sensor output including an impedance value;
• determine that the pericritical fluid has reached a bubble point based at least on a first characteristic change in the impedance value;
• determine that the pericritical fluid has reached a dew point based at least on a second characteristic change in the impedance value, the second characteristic change being different from the first characteristic change;
• and
• output a control signal to control at least one controllable component of the thermal management system based at least on the bubble point and the dew point.