Turbomachine blade with optimised cooling

Turbine blade of a turbomachine such as a turboprop or a turbojet, the blade comprising:

• a root (P), an airfoil (12) supported on the root (P) and extending along a length direction (EV), terminating at a tip (S), the airfoil (12) comprising a leading edge (17) and a trailing edge (18) located downstream from the leading edge (17), the airfoil (12) comprising an intrados wall (20) and an extrados wall (21) at a spacing from each other and connecting the leading edge (17) to the trailing edge (18), this airfoil also comprising:
• cooling ducts (41, 52, 47, 54) each extending laterally from the extrados wall (21) as far as an upstream internal wall (40) or as far as a downstream internal wall (49);
• an upstream lateral cavity (37) and a downstream lateral cavity (38) extending along the intrados wall (20) to form a heat shield, at a spacing from each other along this intrados wall (20);
• the upstream lateral cavity (37) extending laterally from the intrados wall (20) as far as the upstream internal wall (40) along a thickness of less than its length along the intrados wall (20);
• the downstream lateral cavity (38) extending laterally from the intrados wall (20) as far as the downstream internal wall (49) along a thickness of less than its length along the intrados wall (20);
• a cooling conduit (53) extending transversely from the intrados wall (20) as far as the extrados wall (21) between the upstream lateral cavity (37) and the downstream lateral cavity (38).