Analysis of Inducer Recirculating Inlet Flow

• Published in: Journal of propulsion and power 2003-07, Vol.19 (4), p.521-528
• Main Authors: Bario, Francois, Faure, Thierry M, Jondeau, Emmanuel, Normand, Jean-Luc, Duc, Jean-Michel Nguyen
• Format: Article
• Language: English
• Subjects: Fluid mechanics; Inlet flow; Mechanics; Physics
• ISSN: 0748-4658; 1533-3876
• DOI: 10.2514/2.6145

The mean and turbulent features of inducer inlet flow covering various operating points of a centrifugal pump are analyzed. Measurements are conducted in an air test facility with a five-hole pressure probe and an X-wire probe. For flow rates lower than the design flow rate, the recirculation located upstream of the inducer is very strong and creates a global rotation of the fluid from the tip to the hub, upstream of the inducer. The axial extent of the separated flow decreases as the flow rate increases. The stagnation pressure in this region is higher than the upstream stagnation pressure and can reach several times the inlet dynamic head. In the inlet channel axis, within the recirculated flow, the stagnation pressure is lower than what is found for upstream stations outside the recirculation. This can be related to upstream fluid motion and mixing with the inverse flow, providing stagnation pressure losses. For the flow rates where the recirculation region is large, the incoming flow is deflected toward the hub. Phase-averaged measurements in the inducer inlet show the main time-dependant flow features and their evolution with the flow rate. The analysis shows that, at design and higher flow rates, the evolution of the meridional velocity is correlated with the evolution of the relative flow angle. Relative velocity is not affected by the blade leading edge and is constant at a given radius. The change in the axial velocity is mainly due to the sudden change of the relative flow angle before the blade leading edge. (Author)