Turbomachine designed to operate in turning gear mode

1. A power plant comprising:

a first turbine engine including

a compressor;

a combustion chamber situated downstream from the compressor for combustion of a mixture of fuel and of air coming from the compressor;

a first turbine for expanding a combustion gas coming from the combustion chamber and driving the compressor via a first rotary shaft;

an actuator device for actuating said first rotary shaft to keep the first turbine and the compressor in rotation while the combustion chamber is extinguished; and

a lubrication circuit for lubricating at least one bearing of said first rotary shaft; and

a second turbine engine,

wherein the lubrication circuit of the first turbine engine passes through at least one heat exchanger arranged so as to transfer heat from the second turbine engine to a lubricant in the lubrication circuit of the first turbine engine when a temperature of the lubricant in the lubrication circuit of the first turbine engine drops below a first predetermined threshold during rotation of the first turbine and the compressor of the first turbine engine with the combustion chamber of the first turbine engine extinguished.

2. A method of regulating a temperature of a lubricant in a lubrication circuit of a first turbine engine comprising at least: a compressor; a combustion chamber situated downstream from the compressor for combustion of a mixture of fuel and of air coming from the compressor; a first turbine for expanding combustion gas coming from the combustion chamber and driving the compressor via a first rotary shaft; and an actuator device for actuating said first rotary shaft, the method comprising:

directing the lubricant in the lubrication circuit of the first turbine engine, which serves to lubricate at least one bearing of said first rotary shaft, through a heat exchanger having said lubrication circuit passing therethrough and transferring heat from a second turbine engine to the lubricant in the lubrication circuit of the first turbine engine in order to heat the lubricant in the lubrication circuit of the first turbine engine when the temperature of the lubricant in the lubrication circuit of the first turbine engine drops below a first predetermined threshold while the first turbine and the compressor are being kept in rotation by said actuator device with the combustion chamber extinguished.

3. The temperature regulation method according to claim 2 , wherein the lubricant in the lubrication circuit of the first turbine engine is directed through a heat sink through which the lubrication circuit of the first turbine engine passes in order to cool the lubricant in the lubrication circuit of the first turbine engine when the temperature of the lubricant in the lubrication circuit of the first turbine engine exceeds a second predetermined threshold while the combustion chamber is lighted.

4. The temperature regulation method according to claim 2 , wherein the heat exchanger is a lubricant/lubricant heat exchanger transferring the heat from a lubricant in a lubrication circuit of the second turbine engine to the lubricant in the lubrication circuit of the first turbine engine.

5. The power plant according to claim 1 , wherein the at least one heat exchanger comprises a lubricant/lubricant heat exchanger for transferring the heat from a lubricant in a lubrication circuit of the second turbine engine to the lubricant in the lubrication circuit of the first turbine engine.

6. The power plant according to claim 1 , wherein the lubrication circuit of the first turbine engine includes a closable bypass duct around a heat source.

7. The power plant according to claim 1 , wherein the lubrication circuit of the first turbine engine also passes through at least one heat sink for cooling the lubricant in the lubrication circuit of the first turbine engine when the combustion chamber is lighted.