A superelement-based method for computing unsteady three-dimensional potential flows in hydraulic turbomachines

✍ Scribed by Kruyt, N. P. ;van Esch, B. P. M. ;Jonker, J. B.

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 511 KB
• Volume: 15
• Category: Article
• ISSN: 1069-8299
• DOI: 10.1002/(sici)1099-0887(199906/07)15:6<381::aid-cnm252>3.0.co;2-k

✦ Synopsis

A numerical method is presented for the computation of unsteady, three-dimensional potential ¯ows in hydraulic pumps and turbines. The superelement method has been extended in order to eliminate slave degrees of freedom not only from the governing Laplace equation, but also from the Kutta conditions. The resulting superelement formulation is invariant under rotation. Therefore the geometrical symmetry of the ¯ow channels in the rotor can be exploited. This makes the method especially suitable to performing fully coupled computations of the unsteady ¯ow phenomena in both rotor and stator, the so-called rotor±stator interaction.

The developed numerical method is used to simulate the unsteady ¯ow in an industrial mixed-¯ow pump. Two types of simulation are considered: one in which unsteady wakes behind the trailing edges of the rotor blades are taken into account and one in which these are neglected. Results are given that show the importance of unsteady ¯ow phenomena. However, the computed head-capacity curve is hardly in¯uenced by whether or not unsteady wakes are taken into account.