Platform seal in a turbomachine rotor, method for improving the seal between a platform and a turbomachine blade

An elastomer material seal for an interleaved platform between two adjacent blades in a turbomachine rotor, of elongate shape with an upstream edge and a downstream edge, the seal including an upstream zone and a downstream zone between the upstream and downstream edges, the seal comprising transversely, in the widthwise direction:

• a contact part which is circular or oval;
• an attachment part;
• a flexible part between the attachment part and the contact part, the flexible part being narrower than the contact part;
• and
• a local reinforcement of the flexible part disposed only in the downstream zone of the seal,
• wherein the local reinforcement of the flexible part includes at least one transverse rib on the flexible part disposed only in the downstream zone of the seal, and
• wherein the upstream zone extends substantially between one half to two-thirds of a length of the seal from the upstream edge.