Investigation of Shock-Wave/Boundary-Layer Interaction on Aeroelastic Stability: Towards Active Control

2016 ◽  
Author(s):  
Quentin Rendu ◽  
Yannick Rozenberg ◽  
Stéphane Aubert ◽  
Pascal Ferrand
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Pressure Fluctuations ◽  
Strong Shock ◽  
Separated Flow ◽  
Navier Stokes ◽  
Pressure Waves ◽  
Aeroelastic Stability ◽  
Design And Optimization ◽  
Boundary Layer Interaction

In order to predict oscillating loads on a structure, time-linearized methods are fast enough to be routinely used in design and optimization steps of a turbomachine stage. In this work, frequency-domain time-linearized Navier-Stokes computations are proposed to predict the unsteady separated flow generated by an oscillating bump in a transonic nozzle. We also investigate the interaction of backward traveling pressure waves and moving surface on the unsteady behavior of a strong shock-wave with separated boundary-layer. This case is representative of transonic stall flutter of a compressor blade submitted to downstream stator potential effects. The influence of frequency is first investigated on a generic oscillating bump to identify the most unstable configuration. Introducing back pressure fluctuations, we then show that the aeroelastic stability of the system depends on the phase-shift between the fluctuations and the bump motion. Finally, we propose to actively control the instability by generating backward traveling pressure waves at prescribed amplitude, frequency and phase.

Influence of Acoustic Blockage on Flutter Instability in a Transonic Nozzle

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Quentin Rendu ◽  
Yannick Rozenberg ◽  
Stéphane Aubert ◽  
Pascal Ferrand
Keyword(s):  
Active Control ◽  
Separated Flow ◽  
Compressor Blade ◽  
Navier Stokes ◽  
Pressure Waves ◽  
Aeroelastic Stability ◽  
Design And Optimization ◽  
Flutter Instability ◽  
Unstable Configuration ◽  
Low Amplitude

In order to predict oscillating loads on a structure, time-linearized methods are fast enough to be routinely used in design and optimization steps of a turbomachine stage. In this work, frequency-domain time-linearized Navier–Stokes computations are proposed to predict the unsteady separated flow generated by an oscillating bump in a transonic nozzle. The influence of regressive pressure waves on the aeroelastic stability is investigated. This case is representative of flutter of a compressor blade submitted to downstream stator potential effects. The influence of frequency is first investigated on a generic oscillating bump to identify the most unstable configuration. Introducing backward traveling pressure waves, it is then showed that aeroelastic stability of the system depends on the phase shift between the wave's source and the bump motion. Finally, feasibility of active control through backward traveling pressure waves is evaluated. The results show a high stabilizing effect even for low amplitude, opening new perspectives for the active control of choke flutter.

Unsteady Numerical Simulation in a Supersonic Compressor Cascade with a Strong Shock Wave

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Shaowen Chen ◽  
Qinghe Meng ◽  
Yueqi Liu ◽  
Hongyan Liu ◽  
Songtao Wang
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Low Frequency ◽  
Strong Shock ◽  
Oblique Shock Wave ◽  
Compressor Cascade ◽  
Eddy Simulation ◽  
Boundary Layer Interaction ◽  
Unsteady Numerical Simulation ◽  
Wave Boundary

Abstract The most important flow behaviour of supersonic compressor cascades is the shock wave boundary layer interaction (SWBLI). Large eddy simulation (LES) and multiple analysing methods are applied in current study to capture more details of the flow field. It is noted that the LES can catch the dual peaks feature near the SWBLI region with respect to the experimental results. Besides, SWBLI is not only the main losses source in the cascade, but also the most important origin of the unsteadiness behaviour. The high frequency signals correspond to the coherent structure in the boundary layer and dissipate downstream in the cascade, while the low frequency signals relate to the motion of the reflection point of the passage oblique shock wave and dominate the frequency spectrum downstream.

scholarly journals Separated shear layer effect on shock-wave/turbulent-boundary-layer interaction unsteadiness

2018 ◽  
Vol 848 ◽  
pp. 154-192 ◽  
Author(s):  
David Estruch-Samper ◽  
Gaurav Chandola
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Turbulent Boundary Layer ◽  
Shear Layer ◽  
Low Frequency ◽  
Separated Flow ◽  
Layer Interaction ◽  
Separation Shock ◽  
Separated Shear Layer ◽  
Boundary Layer Interaction

This paper presents an experimental study on shock-wave/turbulent-boundary-layer interaction unsteadiness and delves specifically into the shear layer’s role. A range of axisymmetric step-induced interactions is investigated and the scale of separation is altered by over an order of magnitude – mass in the recirculation by two orders – while subjected to constant separation-shock strength. The effect of the separated shear layer on interaction unsteadiness is thus isolated and its kinematics are characterised. Results point at a mechanism whereby the depletion of separated flow is dictated by the state of the large eddy structures at their departure from the bubble. Low-frequency pulsations are found to adjust in response and sustain a reconciling view of an entrainment–recharge process, with both an inherent effect of the upstream boundary layer on shear layer inception and an increase in the mass locally acquired by eddies as they develop downstream.

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