Turbomachine comprising a heat exchanger between a fuel circuit and two lubricant circuits

A turbomachine comprising:

• a heat exchanger;
• a first circuit of a first fluid, the first circuit comprising two ducts in the heat exchanger;
• a second circuit of a second fluid;
• and
• a third circuit of a third fluid,
• the second circuit comprising a first channel in the heat exchanger and the third circuit comprising a second channel in the heat exchanger,
• each of the first channel and the second channel being contiguous to one of the two ducts so as to be in thermal contact with one of the two ducts,
• the first channel and the second channel being contiguous to each other so as to be in thermal contact with each other, and
• the heat exchanger comprising a section in which the two ducts, the first channel and the second channel are locally parallel to each other,
• wherein the first fluid is a fuel, and each of the second fluid and the third fluid is a lubricant.