Linear High Speed Compressor Stator Cascade for Active Flow Control Investigations
- Compressor Cascade
- © TUB F1
Aircraft manufacturers and airlines demand for
highly efficient engines to address the more and more stringent
requirements in terms of economy and environmental compatibility.
This target requires light and compact propulsion systems,
leading to the necessity to reduce the weight of the single
components. Within the compressor module, the number of the required
stages can be minimized by a higher stage pressure ratio at constant
total pressure ratio. This can be done by a stronger turning of the
ﬂow within the passage of a supercritical compressor cascade.
Nevertheless, separation needs to be avoided, one approach being
active ﬂow control.
At the Technical University of Berlin projects investigating active ﬂow control concepts have been executed within the Collaborative Research Center 557, Control of turbulent shear ﬂows.
At the department of Aeronautics and Astronautics of the Technical University of Berlin, a linear stator cascade test facility for active ﬂow control investigations was developed and tested at high speed ﬂow conditions. The compressor blades were designed as critically loaded controled diﬀusion airfoils (CDA) for an upstream Mach number of M = 0.75 and a Reynolds number of Re = 1.1 • 10^6 based on axial chord.
As a basis for the development of a closed-loop active ﬂow control method, a detailed investigation of the ﬂow ﬁeld without actuation is necessary. Five-hole probes have been used to determine the pressure ﬁeld and the ﬂow direction of the wake behind the compressor blade. Furthermore an analysis of the baseline cascade ﬂow by oil ﬂow pattern reveals complex three-dimensional secondary ﬂow phenomena. On the suction side of the blades close to the leading edge, a laminar separation bubble is observed. Where blade and side walls meet, corner stall is developing. Caused by the blade aspect ratio of 0.8, the passage ﬂow is strongly inﬂuenced by these vortices. Uniform main passage ﬂow is thus constricted to the midspan region, leading to a reduction of the passage eﬃciency. The aim is to investigate how the secondary ﬂow phenomena can be supressed by active ﬂow control methods to receive a higher stage pressure ratio or lower total pressure losses respectively and where limits of these methods can be found.
For this purpose, actuators for steady and pulsed blowing through a side wall blowing nozzle were developed. Active ﬂow control investigations have been carried out in the cascade test rig for diﬀerent incidences and inﬂow Mach numbers and variations of the jets mass ﬂow rate, the velocity ratio and the actuation frequency to investigate the inﬂuence of the injected air on the cascade ﬂow.
Person of contact: Dr.-Ing. Christine Tiedemann
Determination of the
pressure distribution and fluctuations of the transonic flow in a
highly loaded compressor
K. Hummel, C. Tiedemann, D. Peitsch
Deutscher Luft- und Raumfahrtkongress 2013,
Stuttgart, Germany, September 10-12 2013, DLRK 2013-301482
Identification of surrogate control variables for a robust active flow controller of an experimental high speed stator cascade
S. Steinberg, C. Tiedemann, R. King, D. Peitsch
ASME Turbo Expo 2013,
San Antonio, USA, June 3-7 2013, GT2013-94179
Identifikation einer Regelgröße zur aktiven Strömungskontrolle an einer linearen Verdichterkaskade im kompressiblen Machzahlbereich
C. Tiedemann, S. Steinberg, D. Peitsch, R. King
Deutscher Luft- und Raumfahrtkongress 2012,
Berlin, Germany, September 10-12 2012, DLRK 2012-281267
A new linear high speed compressor stator cascade for active flow control investigations
C. Tiedemann, A. Heinrich, D. Peitsch
6th AIAA Flow Control Conference,
New Orleans, USA, June 25-28 2012, AIAA-2012-3251