Gas turbine engine with bow wave mitigation

A gas turbine engine, comprising:

• a turbomachine comprising a compressor section, a combustion section, and a turbine section collectively defining at least in part a working gas flow path, the turbine section comprising:
• a band comprising an upstream end and a downstream end, the band extending between the upstream end and the downstream end, the band at least partially defining the working gas flow path, and
• a plurality of airfoils extending into the working gas flow path from the band, wherein each airfoil of the plurality of airfoils includes a leading edge, a trailing edge, a first side extending between the leading edge and the trailing edge, and a second side opposite the first side and extending between the leading edge and the trailing edge, and wherein each of the plurality of airfoils is symmetric across an airfoil centerline extending through a center of each of the plurality of airfoils;
• wherein the upstream end of the band defines a valley portion adjacent the leading edge of each of the plurality of airfoils and a pair of hill portions on opposing sides of the valley portion.