Method of estimating the temperature of the fuel leaving a turbomachine exchanger
A method for estimating the temperature of the fuel entering a turbomachine injector, the turbomachine including engine spaces and an oil/fuel exchanger upstream of the injector, the engine spaces and the oil/fuel exchanger having oil passing through them, the oil/fuel exchanger having an efficiency, the engine spaces including a high-pressure spool, the method including (a) measuring the temperature of the oil entering the engine spaces; (b) measuring the rotational speed of the high-pressure spool; (c) calculating the temperature of the fuel leaving the oil/fuel exchanger using the temperature of the oil entering the engine spaces and the rotational speed of the high-pressure spool.
1. Method for controlling operation of a turbomachine of an aircraft, the turbomachine comprising an oil/fuel exchanger and engine spaces, the engine spaces and the oil/fuel exchanger having oil passing through them, the oil/fuel exchanger having an efficiency, the engine spaces comprising a high-pressure spool, the method comprising:
measuring, via a first sensor, a temperature of oil entering the engine spaces;
measuring, via a second sensor, a rotational speed of the high-pressure spool;
estimating, by a computer installed in the turbomachine, a temperature of fuel leaving the oil/fuel exchanger from calculations using the temperature of the oil entering the engine spaces and the rotational speed of the high-pressure spool; and
controlling the operation of the turbomachine based on the estimated temperature.
2. Method according to claim 1 , wherein estimating the temperature of the fuel leaving the oil/fuel exchanger comprises calculating the temperature of the oil leaving the engine spaces from the rotational speed of the high-pressure spool and the temperature of the oil entering the engine spaces.
3. Method according to claim 2 , wherein the temperature of the oil leaving the engine spaces is calculated by:
calculating the oil flow rate in the engine spaces from the rotational speed of the high-pressure spool;
calculating the thermal power dissipated by the engine spaces from the rotational speed of the high-pressure spool;
calculating the density and the specific heat of the oil using the temperature of the oil entering the engine spaces;
calculating the temperature of the oil leaving the engine spaces from the oil flow rate, the thermal power dissipated by the engine spaces, the density and the specific heat of the oil.
4. Method according to claim 3 , further comprising determining the altitude of the turbomachine, the oil flow rate in the engine spaces being calculated using the altitude of the turbomachine.
5. Method according to claim 2 , wherein estimating the temperature of the fuel leaving the oil/fuel exchanger further comprises:
calculating the temperature of the fuel entering the oil/fuel exchanger using the temperature of the oil entering and leaving the engine spaces and the efficiency of the exchanger;
calculating the density and the specific heat of the fuel using the temperature of the fuel entering the oil/fuel exchanger;
calculating the flow rate of the fuel from the rotational speed of the high-pressure spool;
calculating the temperature of the fuel leaving the oil/fuel exchanger using the temperature of the fuel entering the oil/fuel exchanger, the density and the specific heat of the fuel, the fuel flow rate.
6. Method according to claim 2 , wherein the turbomachine further comprises an air/oil exchanger between the engine spaces and the oil/fuel exchanger, the turbomachine further comprising a fan, the method further comprising measuring the temperature of the air upstream of the fan.
7. Method according to claim 6 , wherein estimating the temperature of the fuel leaving the oil/fuel exchanger further comprises calculating the temperature of the oil leaving the air/oil exchanger using the temperature of the air upstream of the fan and the temperature of the oil leaving the engine spaces.
8. Method according to claim 7 , wherein estimating the temperature of the fuel leaving the oil/fuel exchanger further comprises:
calculating the temperature of the fuel entering the oil/fuel exchanger using the temperature of the oil entering the engine spaces and the temperature of the oil leaving the air/oil exchanger and the efficiency of the exchanger;
calculating the density and the specific heat of the fuel using the temperature of the fuel entering the oil/fuel exchanger;
calculating the flow rate of the fuel from the rotational speed of the high-pressure spool;
calculating the temperature of the fuel leaving the oil/fuel exchanger using the temperature of the fuel entering the oil/fuel exchanger, the density and the specific heat of the fuel, the fuel flow rate.
9. Method according to claim 1 , wherein the first sensor is a temperature sensor.
10. Method according to claim 1 , wherein the second sensor is a geared inductive sensor.
11. Turbomachine of an aircraft, the turbomachine comprising:
an oil/fuel exchanger and engine spaces, the engine spaces and the oil/fuel exchanger having oil passing through them, the oil/fuel exchanger having an efficiency, the engine spaces comprising a high-pressure spool;
a first sensor configured to measure a temperature of oil entering the engine spaces;
a second sensor configured to measure a rotational speed of the high-pressure spool; and
a computer operative to estimate a temperature of fuel leaving the oil/fuel exchanger from calculations using the temperature of the oil entering the engine spaces and the rotational speed of the high-pressure spool.
12. Turbomachine according to claim 11 , wherein the second sensor is a geared inductive sensor.