Turbomachine stator element

#The present disclosure relates to the field of turbomachines, and in particular to dual-flow turbomachines in which air flows from upstream to downstream. It relates more precisely, but not exclusively, to a turbomachine stator element comprising stator vanes.

#It is known from the double flow turbomachines comprising a mobile fan arranged upstream of a gas generator according to the flow of gases in the turbomachine. The gas generator is housed in an annular inner casing while the fan is housed in an annular outer casing. These inner and outer casings are separated by an annular inter-duct casing, so as to delimit a primary duct and a secondary duct. The fan comprises fan vanes with the free end facing the outer casing, so as to compress an incident air stream at least in the secondary duct, and preferably also in the primary duct. The turbomachine is called as a ducted fan turbomachine. The air flow circulating in the primary duct is conventionally compressed by compressor stages of the turbomachine before entering the combustion chamber. The combustion energy is recovered by turbine stages which participate in driving the compressor stages and the fan. The air flow circulating in the secondary duct contributes to the thrust of the turbomachine.

#Classically, the secondary duct comprises stator vanes downstream of the fan, known as rectifiers or outlet guide vanes (OGV). These stator vanes are arranged radially from the outer surface of the inter-duct casing, downstream of the fan vanes, and help to straighten the flow generated and deflected by the fan as it rotates. Flow straightening allows the static pressure to increase by reducing the flow velocity in the fixed mark, but is accompanied by a total pressure loss. The stator vanes are designed to minimize these losses, which degrade their behaviour. However, there are also friction losses and losses caused by flow vortex. The flow vortex is generated due to the presence of a wall at the root of each vane. These flow vortices take on a roughly horseshoe shape and are distributed on the pressure side and suction side of the vanes. At its entry into a passage formed between two adjacent vanes, the flow vortex migrates from the pressure side of one vane to the suction side of the adjacent vane. When the vortex hits the suction side of the vane, it can give rise to an aerodynamic separation.

#The disclosed subject matter will be better understood and other details, characteristics and advantages thereof will appear when reading the following description made as a non-limitative example and with reference to the appended drawings in which:

#FIG. 1 schematically represents a turbomachine with a fan upstream of a gas generator,

#FIG. 2 is a perspective view of an example of a stator vane to which the disclosed subject matter can be applied,

#FIG. 1 illustrates a turbomachine 50 such as an aircraft turbojet engine to which the present disclosure applies. This turbomachine 50 is here a double-flow turbomachine which extends along a longitudinal axis X. The turbomachine 50 generally comprises an external nacelle 51 surrounding a gas generator 52 upstream of which is mounted a fan 53. In the present disclosure, and in a general manner, the terms “upstream” and “downstream” are defined in relation to the flow of gases in the turbomachine. The terms “upper” and “lower” are defined with respect to a radial axis Z perpendicular to the axis X and with respect to the distance from the longitudinal axis X. A transverse axis Y is also perpendicular to the longitudinal axis X and to the radial axis Z. These axes, X, Y, Z shown in FIG. 1 form a Cartesian coordinate system.

#In this example, the gas generator 52 comprises, from upstream to downstream, a low pressure compressor 54, a high pressure compressor 55, a combustion chamber 56, a high pressure turbine 57 and a low pressure turbine 58. The gas generator 52 is housed around an internal casing 59.

#The fan 53 is shrouded here. It is also housed in the nacelle 51. The fan 53 compresses an air flow F entering the turbomachine 50 which is divided into a primary flow circulating in an annular primary duct V1 which passes through the gas generator 52 and a secondary flow circulating in an annular secondary duct V2 around the gas generator 52. In particular, the primary duct V1 and the secondary duct V2 are separated by an annular inter-duct casing 60 arranged between the nacelle 51 and the internal casing 59. The flow of hot air circulating in the primary duct V1 is conventionally compressed by compressor stages 54, 55 before entering the combustion chamber 56. The combustion energy is recovered by turbine stages 57, 58 which drive the compressor stages and the fan. The flow of cold air circulating in the secondary duct V2 is oriented along the longitudinal axis and contributes most of the thrust of the turbomachine.