Patent ID: 7389643

Claim:
A venturi for a combustor comprising: a double wall venturi chamber having an inner wall defining a converging section, a diverging section and a cylindrical section downstream of the converging and diverging sections, and said interior wall further defining a venturi zone in which compressed air, fuel and combustion products flow downstream through the converging section, diverging section and cylindrical section, wherein the inner wall is devoid of air outlets in the converging section; an outer wall of the double wall venturi chamber; a cooling gas passage between the outer wall and the inner wall of the venturi chamber, including through the converging section, the diverging section and the cylindrical section; a least one cooling gas inlet in the outer wall of the venturi chamber, wherein the cooling gas inlet is proximate at least one of the converging section and the diverging section, an additional cooling gas inlet in the outer wall of the double wall venturi chamber cylindrical section; and at least one cooling gas outlet in the inner wall of the venturi chamber, wherein said cooling gas outlet is in at least one of the diverging and the cylindrical section, and the outlet is downstream of the at least one cooling gas inlet and upstream of an axial end of the venturi chamber, wherein the axial end of the chamber is devoid of a cooling gas outlet.