Aerodynamic analysis of the Vulcain 2 LOX turbine manifold

Turbomachinery components used in rocket engines are submitted to extreme aerothermal loads. To ensure the safe operation of the turbine rotor, the sources of aerodynamic unsteadiness must be identified and quantified. The present investigation addresses the aerodynamic flow field in the turbine manifold and nozzle guide vanes of the Vulcain 2 LOX turbine, time-averaged numerical and experimental surveys are presented. A specific test rig was designed to allow both steady and unsteady cold flow traverses. Micro-thermocouples, pneumatic and piezo-resistive probes were used to monitor the total temperature, static and total pressure. The unsteady pressure data in the manifold and vane outlet exhibit a dominant frequency corresponding to the vortex shedding originating from the upstream regulation valve. The cross-correlation of the raw unsteady pressure revealed a perturbation travelling at sonic speeds upstream of the core flow in the manifold. The dominant frequencies and harmonics amplitudes of the fluctuations downstream of the supersonic nozzle are quantified using sliding time windows at various locations along the circumferential direction.