Flow Control

FDB defines FC as the collection of techniques used for locally improvement of flow conditions around and through components. FC often improves performance at operation points that differs from the design or optimum operation point. The aerospace industries uses a number of such techniques and solutions such as vortex-generation distributed along the span of the wing, and chevrons at the trailing edge of the outer duct exit of the gas turbine engines. The former FC solutions improves lift/drag ratio at high angle-of-attacks conditions during take-off and landing, while the latter mitigate noise. Both being typical FC solutions in that they solve secondary problems, but with negligible impact on normal or main operation of the same airplane.

FC makes up a part of fluid dynamic that enjoys a broad interface between academia and the industry, and mainly because the economic gains using FC especially relates to large or complex industrial flow systems. Generally, the success of FC products relies on superior knowledge of the main flow object, being an airplane or a hydropower turbine, as well as of the FC technology itself, such as vortex generators or injection systems.

FDB actively pursue Flow Technology, and our activities include:

  1. By shooting water tangentially into the hydroturbine draft tube, DiffCon mitigates pressure pulsations at off design operation and allows an expanded allowable operation range of the same unit. FDB’s Håkon Francke completed his PhD where he focused on design optimization over the parameter-set used for describing the DiffCon- system.
  2. Vortex generators for mitigation load oscillations due to cavitation and free gas in liquids. Studies on FC techniques made experimentally at the SAFL-UMN cavitation tunnel. FDB’s Jarle Ekanger’s PhD work included parts of these studies.
  3. Impedance control by presence of free gas in pipe flows. FDB’s Ingrid Vilberg’s PhD work includes studies of the effect on hydropower water conduits dynamics performance as a function of gas content.

FDB’s research work currently receives partial funding from the Research Council of Norway, the Industrial PhD scheme, and the regional research fund for Rogaland, Hordaland and Sogn & Fjordane, RFF-Vest.