recent years, turbomachinery research has focused on investigations of
unsteady flow phenomena, including secondary flows or rotor-stator
interactions. On the one hand, CFD methods are being developed and
applied to study these phenomena. On the other hand, modern measurement
techniques are also under intense development to accurately measure time
varying phenomena. The research focus of the instrumentation group at
LEC is both the development of new measurement techniques and the
further development of existing measurement techniques for their
application in harsh turbomachinery environments. One aspect of this
work is hardware design, for example, sensor design and packaging
solutions (see Fig. 1). Another aspect is the design and implementation
of data acquisition and control software and hardware in order to apply
the measurement techniques in either LEC facilities or the experimental
test rigs of our industrial partners.
Adaptive Flow Measurement Algorithm
There is great interest in the industrial setting to reduce the required time for turbomachinery tests, as this reduces product development costs and thereby maintains competitiveness. We have developed a flow adaptive traversing algorithm that automatically identifies flow regions of interest, such as shear flows, secondary flows, and wakes, through user-defined detection functions, and adds additional measurement points. Therefore higher measurement fidelity is obtained in these regions in comparison to a traditional measurement method. The flow adaptive 2D traversing algorithm resolves the overall flow field with 75% fewer measurement points without a loss of measurement accuracy and is therefore 81% quicker compared to making measurements on a uniform measurement grid.
Fast Response Entropy Probe
For steady flows, the losses can be related to changes in the stagnation pressure. However, in turbomachines the flow is inherently unsteady, and both the relative stagnation pressure and the relative stagnation temperature can change. In order to provide a better quantification of the aerothermal losses in turbomachines, LEC has developed and built a new fast response entropy probe, FENT. The design of this probe provides high spatial resolution, high temperature sensitivity, and robustness, which ensure that the unsteady total temperature measurement capability is in the same range as that of the unsteady total pressure.
The probe has been demonstrated in several facilities and proven its robustness in flows including high Mach numbers and large temperature gradients. These applications show that the miniature fast response entropy probe can provide a reliable quantification of unsteady losses and new insight into the aerothermal mixing mechanisms in turbomachinery flows.
For more information, please contact: Mansour, Michel, Dr
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