Experimental AFC Approaches on a Highly Loaded Compressor Cascade

Abstract

Abstract. This paper describes the impact of active separation control by means of pulsed blowing in a highly loaded compressor cascade. Experimental investigations with AFC were undertaken in order to increase the performance of the stator cascade. Two different concepts of actuation were tried. At first, pulsed blowing out of the casing was used to reduce the secondary flow structures. Secondly, the flow was excited with actuators mounted on the blade's suction side, suppressing the pressureinduced flow separation. In a final step, both actuator concepts were combined with selected excitation amplitudes and frequencies. These demonstrations show that the gain achieved in both actuator concepts can be combined, using certain excitation parameters and no interaction with negative effects occur.

Flow control using unsteady pulsed holed suction with different excitation models in a highly loaded compressor cascade

“…For validation of the present numerical method in the study, the simulated results were compared with the results of wind tunnel experiment. Figure 5 illustrates the comparison between the experimental 9 and numerical results of a highly loaded compressor cascade with a 60 camber angle, which is similar to the current compressor cascade. The distribution of static pressure coefficient at midspan is given in Figure 5 For clearly showing the stagnation point of the static pressure, the static pressure coefficient near the leading edge has been partially enlarged.…”

“…Cerretelli and Kirtley 8 studied the impacts of unsteady blowing in controlling flow separations of a model diffuser, and they found that unsteady blowing can reattach fully the flow and gain the maximum pressure recovery only with the injection momentum of 40% and the blowing power of 70% relative to optimal steady blowing. The experimental and numerical results of Hecklau et al [9][10][11] indicated that the pulse blowing had notable superiorities in mitigating flow separations and reducing cascade losses, and pulse blowing needed less injection mass flow, but it could reach the same performances compared with steady blowing. Therefore, it is confirmed that the UFC techniques mentioned above can gain a more marked boost of aerodynamic performance than the SFC technique.…”

Active Flow Control on a Highly Loaded Compressor Cascade with Non-steady Boundary Conditions

“…9. Influence of actuation on cp distribution [10] Taking the cascade's baseflow into account a relatively large flow separation can be observed at s/S = 65%. In earlier works this separation was successfully avoided using multiple actuators simultaneously.…”

“…Blade actuators avoid flow separation on the blade itself. In earlier works the positive achievements using both side wall and blade actuators were investigated by [9], [10], [11] using pulsed air jets, where a reduction in loss of 10% was realized. The major advantage of pulsed air jets instead of steady ones, as used in [2], is the reduction of the necessary air mass flow rate.…”

A Qualitative Comparison of Unsteady Operated Compressor Stator Cascades with Active Flow Control

“…Active flow control (AFC) opportunities for compressor stators were investigated in [10][11][12][13][14]. Research indicated that pulsed jet actuators (PJA) are more effective for AFC application compared to steady blowing actuators, as shown by Seifert [15] and Hecklau et al [16]. The feasibility of suppression of periodic flow separation phenomena in a unsteady operated compressor stator cascade using PJA was shown by Staats et al [17].…”