Separation Control of Axial Compressor Cascade by Fluidic-Based Excitations

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Xinqian Zheng ◽  
Yangjun Zhang ◽  
Weidong Xing ◽  
Junyue Zhang
Keyword(s):  
Stokes Equations ◽  
Axial Compressor ◽  
Separated Flow ◽  
Synthetic Jet ◽  
Separation Point ◽  
Navier Stokes ◽  
Separation Control ◽  
Compressor Cascade ◽  
Navier Stokes Equations ◽  
Flow Separation Control

Flow separation control was investigated on a compressor cascade using three types of fluidic-based excitations: steady suction, steady blowing, and synthetic jet. By solving unsteady Reynolds–averaged Navier–Stokes equations, the effect of excitation parameters (amplitude, angle, and location) on performance was addressed. The results show that the separated flow can be controlled by the fluidic-based actuators effectively and the time-averaged performance of the flow field can be improved remarkably. Generally, the improvement can be enhanced when the amplitude of excitation is increased. The optimal direction varies with each type of excitations and is related to physical mechanisms underlying the separation control. For two types of steady excitations, the most effective jet location is at a distance upstream of the time-averaged separation point and the synthetic jet is just at the separation point.

Separation Control of Axial Compressor Cascade by Fluidic-Based Excitations

2007 ◽  
Author(s):  
Xinqian Zheng ◽  
Yangjun Zhang ◽  
Weidong Xing ◽  
Junyue Zhang
Keyword(s):  
Axial Compressor ◽  
Separated Flow ◽  
Excitation Amplitude ◽  
Synthetic Jet ◽  
Separation Point ◽  
Separation Control ◽  
Compressor Cascade ◽  
Flow Separation Control ◽  
Physical Mechanisms ◽  
Positive Effect

Flow separation control was explored on a compressor cascade using three types of fluidic-based excitations: steady suction, steady blowing and synthetic jet. By solving unsteady Reynolds-averaged N-S equations, the effect of excitation parameters (amplitude, angle and location) on the performance were presented. The results showed that the separated flow could be controlled by the fluidic-based actuators effectively and the time-mean performance of flow filed could be remarkably improved. Generally, the positive effect is more visible when the excitation amplitude is increased. The optimal direction varies with each type of excitations and is related to physical mechanisms underlying the separation control. For two types of steady excitations, the most effective jet location is at a distance upstream of the time-mean separation point and the synthetic jet is just at the separation point.

Numerical Investigation of Blade Flutter at or Near Stall in Axial Flow Turbomachines

2001 ◽  
Author(s):  
Wolfgang Höhn
Keyword(s):  
Viscous Flow ◽  
Stokes Equations ◽  
Separated Flow ◽  
Parallel Computer ◽  
Navier Stokes ◽  
Computational Domain ◽  
Compressor Cascade ◽  
Governing Equations ◽  
Navier Stokes Equations ◽  
Blade Flutter

During the design of the compressor and turbine stages of today’s aeroengines, aerodynamically induced vibrations become increasingly important since higher blade load and better efficiency are desired. In this paper the development of a method based on the unsteady, compressible Navier-Stokes equations in two dimensions is described in order to study the physics of flutter for unsteady viscous flow around cascaded vibrating blades at stall. The governing equations are solved by a finite difference technique in boundary fitted coordinates. The numerical scheme uses the Advection Upstream Splitting Method to discretize the convective terms and central differences discretizing the viscous terms of the fully non-linear Navier-Stokes equations on a moving H-type mesh. The unsteady governing equations are explicitly and implicitly marched in time in a time-accurate way using a four stage Runge-Kutta scheme on a parallel computer or an implicit scheme of the Beam-Warming type on a single processor. Turbulence is modelled using the Baldwin-Lomax turbulence model. The blade flutter phenomenon is simulated by imposing a harmonic motion on the blade, which consists of harmonic body translation in two directions and a rotation, allowing an interblade phase angle between neighboring blades. Non-reflecting boundary conditions are used for the unsteady analysis at inlet and outlet of the computational domain. The computations are performed on multiple blade passages in order to account for nonlinear effects. A subsonic massively stalled unsteady flow case in a compressor cascade is studied. The results, compared with experiments and the predictions of other researchers, show reasonable agreement for inviscid and viscous flow cases for the investigated flow situations with respect to the Steady and unsteady pressure distribution on the blade in separated flow areas as well as the aeroelastic damping. The results show the applicability of the scheme for stalled flow around cascaded blades. As expected the viscous and inviscid computations show different results in regions where viscous effects are important, i.e. in separated flow areas. In particular, different predictions for inviscid and viscous flow for the aerodynamic damping for the investigated flow cases are found.

Effects of stator splitter blades on aerodynamic performance of a single-stage transonic axial compressor

2020 ◽  
Vol 14 (4) ◽  
pp. 7369-7378
Author(s):  
Ky-Quang Pham ◽  
Xuan-Truong Le ◽  
Cong-Truong Dinh
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Aerodynamic Performance ◽  
Numerical Results ◽  
Single Stage ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Operating Stability ◽  
Length Coverage

Splitter blades located between stator blades in a single-stage axial compressor were proposed and investigated in this work to find their effects on aerodynamic performance and operating stability. Aerodynamic performance of the compressor was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations using the k-e turbulence model with a scalable wall function. The numerical results for the typical performance parameters without stator splitter blades were validated in comparison with experimental data. The numerical results of a parametric study using four geometric parameters (chord length, coverage angle, height and position) of the stator splitter blades showed that the operational stability of the single-stage axial compressor enhances remarkably using the stator splitter blades. The splitters were effective in suppressing flow separation in the stator domain of the compressor at near-stall condition which affects considerably the aerodynamic performance of the compressor.

Detached-Eddy Simulations Over a Simplified Landing Gear

2002 ◽  
Vol 124 (2) ◽  
pp. 413-423 ◽  
Author(s):  
L. S. Hedges ◽  
A. K. Travin ◽  
P. R. Spalart
Keyword(s):  
Stokes Equations ◽  
Separated Flow ◽  
Flow Fields ◽  
Equation Model ◽  
Landing Gear ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Navier Stokes Equations ◽  
Instantaneous Flow ◽  
Eddy Simulation

The flow around a generic airliner landing-gear truck is calculated using the methods of Detached-Eddy Simulation, and of Unsteady Reynolds-Averaged Navier-Stokes Equations, with the Spalart-Allmaras one-equation model. The two simulations have identical numerics, using a multi-block structured grid with about 2.5 million points. The Reynolds number is 6×105. Comparison to the experiment of Lazos shows that the simulations predict the pressure on the wheels accurately for such a massively separated flow with strong interference. DES performs somewhat better than URANS. Drag and lift are not predicted as well. The time-averaged and instantaneous flow fields are studied, particularly to determine their suitability for the physics-based prediction of noise. The two time-averaged flow fields are similar, though the DES shows more turbulence intensity overall. The instantaneous flow fields are very dissimilar. DES develops a much wider range of unsteady scales of motion and appears promising for noise prediction, up to some frequency limit.

A Numerical Study on Performances of Centrifugal Compressor Stages With Different Radial Gaps

2000 ◽  
Author(s):  
K. Sato ◽  
L. He
Keyword(s):  
Centrifugal Compressor ◽  
Stokes Equations ◽  
Numerical Study ◽  
Axial Compressor ◽  
Navier Stokes ◽  
Centrifugal Impeller ◽  
Vaned Diffuser ◽  
Navier Stokes Equations ◽  
Performance Predictions ◽  
Radial Gap

A numerical study of 3D unsteady flows in centrifugal compressor stages solving the Navier-Stokes equations is presented. The emphasis is on the effect of the radial gap between blade rows on the aerodynamic performance. In the numerical tests, Krain’s centrifugal impeller was combined with a DCA (Double Circular Arc) type radial vaned diffuser. The compressor stages with three settings of radial gap ranging from 5 to 15 percent of the impeller trailing edge radius are configured and unsteady flow simulations are carried out to compare the time-averaged efficiencies. The performance predictions show that the efficiency is deteriorated if the radial gap between blade rows is reduced with intensified blade row interaction, which is in contradiction to the general trend for axial compressor stages. In the centrifugal compressors tested, wake chopping by diffuser vanes, which usually benefits efficiency in axial compressor stages, causes unfavourable wake compression through the diffuser passages to deteriorate the efficiency.

II. Analysis of regular and singular motions

1965 ◽  
Vol 285 (1402) ◽  
pp. 400-412 ◽  
Keyword(s):  
Stokes Equations ◽  
Separated Flow ◽  
Fluid Flows ◽  
Flow Patterns ◽  
Navier Stokes ◽  
Flow Properties ◽  
Navier Stokes Equations ◽  
Weakly Singular ◽  
Simultaneous Existence ◽  
Additional Explanation

An eigenmotion analysis of viscous fluid flows around dihedral angles presented in part I of this paper revealed the simultaneous existence of regular and weakly singular motions which are characterized by finite and infinite pressures at the edge of a wedge. Since the derivation of the Navier-Stokes equations is based on the finiteness of the velocity and pressure, the physical meaning of an infinite pressure in the region of operation requires an additional explanation. The present investigations analyse the flow properties of regular and weakly singular motions past a semi-infinite flat plate under symmetric and asymmetric attack. Particular attention is directed to the attached and separated flow patterns which can develop around a sharp edge. The duality of regular and weakly singular motions is shown to exist for most of the typical flow patterns which can be observed in published photographs. The qualitative agreement with photographs is especially satisfactory for regular motions. A brief summary of the essential flow properties of both types is given.

scholarly journals Leakage Effects in the Rotor Tip-Clearance Region of a Multistage Axial Compressor: Part 1 — Innovative Experiments

1998 ◽  
Author(s):  
P. C. Ivey ◽  
M. Swoboda
Keyword(s):  
Numerical Solutions ◽  
Stokes Equations ◽  
Numerical Study ◽  
Measurement Techniques ◽  
Axial Compressor ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Tip Clearance Flow ◽  
Clearance Flow

This paper describes work conducted as part of an experimental and numerical study of leakage effects by numerous Research and Industrial partners. For clarity it is presented in two parts. Part 1 presents measurements of tip-clearance flow for a 3rd stage rotor embedded in a four stage low-speed research compressor. The measurements are innovative and comprise measurements in the rotor relative frame of reference and 3D Laser time-of-flight Anemometry. Both techniques are relevant for improved understanding of multistage compressor flow dynamics and consequently, validated multistage CFD simulations. In part 2 of this paper (see Politis et al 1997b) it is shown that downstream of the rotor passage the location and size of a tip-clearance vortex, identified from both independent measurement techniques in Part 1, is in good agreement with 3D solutions of the Navier-Stokes equations modelling this compressor. These 3D numerical solutions reveal the tip-clearance flow structure using a multiblock grid technique.

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