As an active flow control technology and with the advantages of no moving components, the Sweeping jet actuator has become a hotspot in the field of flow control. However, the linear relationship between oscillation f...As an active flow control technology and with the advantages of no moving components, the Sweeping jet actuator has become a hotspot in the field of flow control. However, the linear relationship between oscillation frequency and momentum coefficient in a sweeping jet actuator makes it difficult to determine the dominant factors that affect control effectiveness. Decoupling the oscillation frequency and momentum coefficient, as well as determining the control mechanism, is the focus of studying the sweeping jet actuator. In this study, a novel sweeping jet actuator is designed using synthetic jets instead of feedback channels and applied to the flow separation control of NACA0018 airfoil. This article studies the control effect under three oscillation frequencies of F<sup>+</sup> = f × c/U<sub>∞</sub> = 1, 10, 100 and three momentum coefficients of C<sub>μ</sub> = 0.45%, 0.625%, 0.9%. The numerical results indicate that all three oscillation frequencies have good control effects on flow separation, and the control effect is best when F<sup>+</sup> = 1, with the maximum lift coefficient increasing by approximately 14% compared to the other two cases. And the sweeping jet actuator has a better ability to control flow separation as the momentum coefficient increases. By decoupling the characteristics of the sweeping jet actuator and conducting numerical analysis of the flow control effect, it will promote its better engineering application in the field of flow control. .展开更多
Unsteady behaviors are important issues in flow control of turbomachinery.Pulsed excitation or suction is widely investigated in compressor cascades.This paper presents a discussion on the unsteady flow control realiz...Unsteady behaviors are important issues in flow control of turbomachinery.Pulsed excitation or suction is widely investigated in compressor cascades.This paper presents a discussion on the unsteady flow control realized by dual sweeping jet actuator(SJA)located on the blade suction surface.The unsteady numerical simulations were utilized to study the effect of applying dual SJAs on controlling the corner separation.With the numerical results,the following conclusions could be drawn with current compressor cascade.A maximum total pressure loss coefficient reduction of 6.8%was obtained.The analysis of the flow field pointed out that the regulation mechanisms of the corner separation were different with each SJA.The SJA ahead achieved an interruption of the suction side boundary layer development and the rear SJA enhanced the interaction and entrainment between the excitation stream and the secondary flows.Meanwhile,the different unsteadiness structures of the flow field frequency spectrum compared with single SJA cases were identified.The first peak frequency corresponded to the difference of the two SJAs and the rest frequencies could be regulated to a base frequency and its harmonic frequencies.展开更多
文摘As an active flow control technology and with the advantages of no moving components, the Sweeping jet actuator has become a hotspot in the field of flow control. However, the linear relationship between oscillation frequency and momentum coefficient in a sweeping jet actuator makes it difficult to determine the dominant factors that affect control effectiveness. Decoupling the oscillation frequency and momentum coefficient, as well as determining the control mechanism, is the focus of studying the sweeping jet actuator. In this study, a novel sweeping jet actuator is designed using synthetic jets instead of feedback channels and applied to the flow separation control of NACA0018 airfoil. This article studies the control effect under three oscillation frequencies of F<sup>+</sup> = f × c/U<sub>∞</sub> = 1, 10, 100 and three momentum coefficients of C<sub>μ</sub> = 0.45%, 0.625%, 0.9%. The numerical results indicate that all three oscillation frequencies have good control effects on flow separation, and the control effect is best when F<sup>+</sup> = 1, with the maximum lift coefficient increasing by approximately 14% compared to the other two cases. And the sweeping jet actuator has a better ability to control flow separation as the momentum coefficient increases. By decoupling the characteristics of the sweeping jet actuator and conducting numerical analysis of the flow control effect, it will promote its better engineering application in the field of flow control. .
基金supported by National Natural Science Foundation of China(Grant No.51776048 and 51436002)。
文摘Unsteady behaviors are important issues in flow control of turbomachinery.Pulsed excitation or suction is widely investigated in compressor cascades.This paper presents a discussion on the unsteady flow control realized by dual sweeping jet actuator(SJA)located on the blade suction surface.The unsteady numerical simulations were utilized to study the effect of applying dual SJAs on controlling the corner separation.With the numerical results,the following conclusions could be drawn with current compressor cascade.A maximum total pressure loss coefficient reduction of 6.8%was obtained.The analysis of the flow field pointed out that the regulation mechanisms of the corner separation were different with each SJA.The SJA ahead achieved an interruption of the suction side boundary layer development and the rear SJA enhanced the interaction and entrainment between the excitation stream and the secondary flows.Meanwhile,the different unsteadiness structures of the flow field frequency spectrum compared with single SJA cases were identified.The first peak frequency corresponded to the difference of the two SJAs and the rest frequencies could be regulated to a base frequency and its harmonic frequencies.
