Numerical and Experimental Investigations of the Cavitation Structure in Inducer

• Applicant: Professor Dr.-Ing. Martin Böhle
• Subject Area: Hydraulic and Turbo Engines and Piston Engines
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 455025217

In the previous project it could be demonstrated that an inducer must not be designed in the axial direction as long as it is prescribed by the established design procedures in order to reach a prescribed pressure rise. Therefore the question arises whether an inducer, which is shorter designed than the established design procedures prescribe, is able to reduce the cavitation completely or sufficiently in axial direction, respectively, so that the following impeller is not affected in its function. This question has not been treated in the open literature until now. Basically, the question arises how long the axial dimension of an inducer must be to fulfil its function (increase of pressure, reduction of cavitation) completely. In the present project criterions are to be developed making it possible to design an inducer with sufficient axial length. In the open scientific literature it is shown that a swept leading edge of an inducer leads to an improvement of the NPSH-behaviour. This could be confirmed by the results of the previous project. It is an open question why a swept leading edge leads to an improved NPSH-behaviour. This question is related to the request to develop criterions of an optimal swept leading edge. In the present project the pressure distribution is to be investigated in the leading edge region in order to find out why a swept leading edges processes a better NPSH-behaviour. Finally, the open literature does not give an answer of the interaction between inducer and impeller. The inducer produced a swirl which is imposed on the inflow side of the in main stream direction following impeller. On the other hand the impeller influences the swirl of the inducer. In the present project this problem is to be treated by investigating the swirl of the inducer without influence of the impeller by measurements and CFD-simulation. After that the influence of the impeller is taken into account. In a last step a modified impeller is produced which works well together with the inducer.

• DFG Programme: Research Grants