A turbomachine, comprising: a first platform including a downstream extending flange; and a second platform downstream of the first platform, wherein the second platform includes a platform body comprising: an airfoil support surface; an axially extending base surface opposite the airfoil support surface; and a leading edge including an upstream extending flange with a raised portion and a trough portion downstream of and radially inward from the raised portion for holding a vortex of fluid flow, wherein the downstream extending flange of the first platform axially overlaps the raised portion of the leading edge of the second platform, characterised in that, when at equilibrium temperature, an axial position of a downstream edge of the downstream extending flange is substantially equal to an axial position of an intersection of the raised portion and the trough portion, an axial length of the raised portion is substantially equal to an axial length of an opening of the trough portion, and in that a radial distance between a bottom of the trough portion and an outer surface of the downstream extending flange is approximately equal to the axial length of the trough portion. a first platform including a downstream extending flange; and a second platform downstream of the first platform, wherein the second platform includes a platform body comprising: an airfoil support surface; an axially extending base surface opposite the airfoil support surface; and a leading edge including an upstream extending flange with a raised portion and a trough portion downstream of and radially inward from the raised portion for holding a vortex of fluid flow, wherein the downstream extending flange of the first platform axially overlaps the raised portion of the leading edge of the second platform, characterised in that, when at equilibrium temperature, an axial position of a downstream edge of the downstream extending flange is substantially equal to an axial position of an intersection of the raised portion and the trough portion, an axial length of the raised portion is substantially equal to an axial length of an opening of the trough portion, and in that a radial distance between a bottom of the trough portion and an outer surface of the downstream extending flange is approximately equal to the axial length of the trough portion. an airfoil support surface; an axially extending base surface opposite the airfoil support surface; and a leading edge including an upstream extending flange with a raised portion and a trough portion downstream of and radially inward from the raised portion for holding a vortex of fluid flow, wherein the downstream extending flange of the first platform axially overlaps the raised portion of the leading edge of the second platform, characterised in that, when at equilibrium temperature, an axial position of a downstream edge of the downstream extending flange is substantially equal to an axial position of an intersection of the raised portion and the trough portion, an axial length of the raised portion is substantially equal to an axial length of an opening of the trough portion, and in that a radial distance between a bottom of the trough portion and an outer surface of the downstream extending flange is approximately equal to the axial length of the trough portion.