Active Control of the Corner Separation on a Highly Loaded Compressor Cascade With Periodic Nonsteady Boundary Conditions by Means of Fluidic Actuators

Staats, Marcel; Nitsche, W.

doi:10.1115/1.4031934

Cited by 37 publications

(8 citation statements)

References 12 publications

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“…As a major consequence, this leads to a variation of the incidence angle at the leading edge of the last compressor stator and the occurrence of unsteady flow characteristics. These have a negative influence on the overall aerodynamic response and the stable operation of the compressor and need to be addressed [3]. Corner vortices and possible corner separation may form in between a blade's suction side and the hub and/or casing-wall as shown by Beselt et.al.…”

Section: Introductionmentioning

confidence: 99%

Numerical and Experimental Investigations on Optimized 3D Compressor Airfoils

Mihalyovics

Brück

Peitsch

et al. 2018

Volume 2A: Turbomachinery

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The objective of the presented work is to perform numerical and experimental studies on compressor stators. This paper presents the modification of a baseline stator design using numerical optimization resulting in a new 3D stator. The Rolls Royce in-house compressible flow solver HYDRA was employed to predict the 3D flow, solving the steady RANS equations with the Spalart-Allmaras turbulence model, and its corresponding discrete adjoint solver. The performance gradients with respect to the input design parameters were used to optimize the stator blade with respect to the total pressure loss over a prescribed incidence range, while additionally minimizing the flow deviation from the axial direction at the stator exit. Non-uniform profile boundary conditions, being derived from the experimental measurements, have been defined at the inlet of the CFD domain. The presented results show a remarkable decrease in the axial exit flow angle deviation and a minor decrease in the total pressure loss. Experiments were conducted on two compressor blade sets investigating the three-dimensional flow in an annular compressor stator cascade. Comparing the baseline flow of the 42° turning stator shows that the optimized stator design minimizes the secondary flow phenomena. The experimental investigation discusses the impact of steady flow conditions on each stator design while focusing on the comparison of the 3D optimized design to the baseline case. The flow conditions were investigated using five-hole probe pressure measurements in the wake of the blades. Furthermore, oil-flow visualization was applied to characterize flow phenomena. These experimental results are compared with the CFD calculations.

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Section: Introductionmentioning

confidence: 99%

Numerical and Experimental Investigations on Optimized 3D Compressor Airfoils

Mihalyovics

Brück

Peitsch

et al. 2018

Volume 2A: Turbomachinery

View full text Add to dashboard Cite

show abstract

“…In recent years, wall-attachment oscillators have been widely studied in airfoil lift augmentation [28], cavity noise suppression [29], and heat conduction enhancement [30,31]. In the field of aero-engines, wall-attachment oscillators have been applied to adjust the thrust vector [32]; control flow separation at the s-shaped inlet [33], corner of compressor stator [34,35], and outlet guide vane of high-load turbine [36]; and reduce loss caused by turbine tip clearance leakage vortex [37].…”

Section: Introductionmentioning

confidence: 99%

Characteristics of a Fluidic Oscillator with Low Frequency and Low Speed and Its Application to Stall Margin Improvement

et al. 2022

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Active flow control methods are commonly used in expanding the operating range of compressors. Indeed, unsteady active control methods are the main focus of researchers due to their effectiveness. For constructing an unsteady active control system, reliable actuators are significant. To compare with conventional actuators such as synthetic jet actuators and rotating valves, fluidic oscillators have structurally robust characteristics and can generate self-excited and self-sustained oscillating jets, which leads to its higher applicability in compressors under severe working conditions. Thus, to explore the feasibility of unsteady active control systems by the usage of fluidic oscillators, a low-frequency and low-speed oscillator is first designed and experimentally studied for improving the stability of a low-speed axial flow compressor. During the experiments, a special casing is designed to install 15 uniformly distributed oscillators in the tip region of compressor. Based on the unsteady micro injections of the rotor tip with rotor rotation frequency, the results indicate that the frequency/period of oscillators are flexible, in which the values are decoupled with the variation of inlet pressure. When the inlet-to-outlet pressure ratio of the oscillator is in the range of 1.1~2.0, the maximum velocity ranges from 30 m/s to 80 m/s. Moreover, the mass flow rate of the single oscillator only varies from 0.017‰ to 0.059‰ from the designed compressor mass flow rate. For the improvement of the compressor stall margin, the value is 3.45% when the total mass flow of oscillators is 0.08% of the designed compressor mass flow.

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“…Over the last two decades this has led to a renaissance in flow control research focusing on both passive and active methods. The variety of applications and concepts is vast and includes boundary layer separation control [1][2][3][4][5][6][7], drag reduction of ground vehicles [8][9][10], unsteady film cooling [11,12], combustion instability control [13], jet vectoring [14], mixing enhancements [15,16], cavity tone and resonance suppression [17,18] as well as the control of secondary flow phenomena in inlet ducts or highly loaded compressors and turbines [19][20][21][22][23]. The enormous amount of published articles regarding different strategies and applications demonstrate not only the huge interest within the aerospace community but also the difficulties and challenges that still FE-20-1221, MAIR persist.…”

Section: Introductionmentioning

confidence: 99%

Fluid Dynamics of a Bistable Diverter Under Ultrasonic Excitation—Part I: Performance Characteristic

Mair

Bacic

2021

Journal of Fluids Engineering

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This paper investigates an ultrasonically driven bistable fluidic diverter at inlet nozzle Mach numbers of up to Mn = 0:3 and operating pressure ratios of up to Pr = 1:1. Part I examines the switching characteristics with respect to nondimensional parameters of excitation amplitude, frequency, required energy, switching time and inlet total pressure. It is shown that to promote switching at turbulent jet Mach numbers of up to Mn=0:3 it is necessary to excite a jet preferred mode of St=0.45 which differs from previously reported laminar jet operation of the similar device. For the reference case the switching time amounts to 1:2 ms suggesting oscillation frequencies of up to 800Hz. Part II is a combined experimental and numerical study that examines the triggered instability modes in the free shear layer using Large Eddy Simulations (LES) and visualises the flow field using Particle Image Velocimetry (PIV).

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Active Control of the Corner Separation on a Highly Loaded Compressor Cascade With Periodic Nonsteady Boundary Conditions by Means of Fluidic Actuators

Cited by 37 publications

References 12 publications

Numerical and Experimental Investigations on Optimized 3D Compressor Airfoils

Numerical and Experimental Investigations on Optimized 3D Compressor Airfoils

Characteristics of a Fluidic Oscillator with Low Frequency and Low Speed and Its Application to Stall Margin Improvement

Fluid Dynamics of a Bistable Diverter Under Ultrasonic Excitation—Part I: Performance Characteristic

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