Study on Flow Mechanism of a Morphing Supercritical Airfoil

Yuanjing Wang,Yu Yan,Binbin Lv,Pengxuan Lei,Wenkui Shi,Zeqi Lu

doi:10.1155/2021/5588056

Yuanjing Wang, Yu Yan + Show 4 more

Open Access

https://doi.org/10.1155/2021/5588056

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Abstract

In order to maintain the best performance in flight, a new concept, morphing aircraft, has been proposed, which can change the real-time aerodynamic characteristics under different flight conditions. The key problem is to figure out the response of strong flow instability caused by structure changes during the morphing. To solve this problem, computational fluid dynamics (CFD) and wind tunnel tests (WTT) were employed. The results show that the deformation of thickness and camber angle of the airfoil will significantly change the distribution of pressure and result in obvious hysteresis loops of lift and drag. With the increase of deformation frequency and amplitude, the instability increases correspondingly. Moreover, the unsteady effect caused by camber deformation is much stronger than that caused by thickness deformation. In addition, the flow structures on the airfoil, such as the shock strength and boundary separation location, have a delay in response to structure changes. Therefore, there will be a hysteresis between airfoil deformation and aerodynamic characteristics, which means strong flow instability.

Highlights

With the development of technology and science, more and more attentions have been paid to the quality and performance of aircrafts [1,2,3]
With the increase of the deformation amplitude, the hysteresis phenomenon becomes more obvious, which is caused by the pressure and vorticity difference at the same position during the thickness deformation process (Figure 10). e area of the hysteresis loop formed by the lift coefficient can be understood as the work required by the external force during the deformation of airfoil
E greater the area, the greater the power required [22]. e influence of thickness deformation frequency is shown in Figure 11. e higher the deformation frequency, the greater the lift/drag force generated by the rate of change of the velocity potential over time

Summary

Introduction

With the development of technology and science, more and more attentions have been paid to the quality and performance of aircrafts [1,2,3]. The impact of configuration changes on the flow structure and aircraft performance is not yet understood, which may hinder the progress of the morphing airfoil. Erefore, it is necessary to study the relationship and response law between the flow and configuration deformation Research institutes, such as NASA and DAPPA, have conducted long-term research on the related technologies of morphing vehicles [4,5,6], as well as a lot of research on aerodynamics. At the same time, using analytical and discrete vortex methods proposed by Gao et al [17, 18], the unsteady aerodynamic characteristics of the morphing airfoil under subsonic/supersonic speed conditions were studied

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Conclusion