Full-Annulus Simulations of Airfoil Clocking in a 1-1/2 Stage Axial Compressor

1999 ◽  
Author(s):  
D. J. Dorney ◽  
D. L. Sondak ◽  
P. G. A. Cizmas ◽  
V. E. Saren ◽  
N. M. Savin
Keyword(s):  
Relative Motion ◽  
High Speed ◽  
Guide Vane ◽  
Research Effort ◽  
Axial Compressor ◽  
Inlet Guide Vane ◽  
Axial Compressors ◽  
Computational Research ◽  
Potential Interactions ◽  
Made In

Axial compressors have inherently unsteady flow fields because of relative motion between rotor and stator airfoils. This relative motion leads to viscous and inviscid (potential) interactions between blade rows. As the number of stages increases in a turbomachine, the buildup of convected wakes can lead to progressively more complex wake/wake and wake/airfoil interactions. Variations in the relative circumferential positions of stators or rotors can change these interactions, leading to different unsteady forcing functions on airfoils and different compressor efficiencies. In addition, as the Mach number increases the interaction between blade rows can be intensified due to potential effects. It has been shown, both experimentally and computationally, that airfoil clocking can be used to improve the efficiency and reduce the unsteadiness in multiple-stage axial turbomachines with equal blade counts in alternate blade rows. While previous investigations have provided an improved understanding of the physics associated with airfoil clocking, more research is needed to determine if airfoil clocking is viable for use in modern gas-turbine compressors. This paper presents the results of a combined experimental/computational research effort to study the physics of airfoil clocking in a high-speed axial compressor. Computational simulations have been performed for eight different clocking positions of the stator airfoils in a 1-1/2 stage high-speed compressor. To accurately model the experimental compressor, full-annulus simulations were conducted using 34 IGV, 35 rotor and 34 stator airfoils. It is common practice to modify blade counts to reduce the computational work required to perform turbomachinery simulations, and this approximation has been made in all computational clocking studies performed to date. A simulation was also performed in the present study with 1 inlet guide vane, 1 rotor airfoil, and 1 stator airfoil to model blade rows with 34 airfoils each in order to examine the effects of this approximation. Time-averaged and unsteady data (including performance and boundary layer quantities) were examined. The predicted results indicate that simulating the full annulus gives better qualitative agreement with the experimental data, as well as more accurately modeling the interaction between adjacent blade rows.

scholarly journals Physics of Airfoil Clocking in a High-Speed Axial Compressor

1998 ◽  
Author(s):  
Daniel J. Dorney ◽  
Om P. Sharma ◽  
Karen L. Gundy-Burlet
Keyword(s):  
Relative Motion ◽  
High Speed ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Unsteady Aerodynamics ◽  
Navier Stokes ◽  
Jet Engines ◽  
Axial Compressors ◽  
Multi Stage ◽  
Significant Performance

Axial compressors have inherently unsteady flow fields because of relative motion between rotor and stator airfoils. This relative motion leads to viscous and inviscid (potential) interactions between blade rows. As the number of stages increases in a turbomachine, the buildup of convected wakes can lead to progressively more complex wake/wake and wake/airfoil interactions. Variations in the relative circumferential positions of stators or rotors can change these interactions, leading to different unsteady forcing functions on airfoils and different compressor efficiencies. In addition, as the Mach number increases the interaction between blade rows can be intensified due to potential effects. In the current study an unsteady, quasi-three-dimensional Navier-Stokes analysis has been used to investigate the unsteady aerodynamics of stator clocking in a 1-1/2 stage compressor, typical of back stages used in high-pressure compressors of advanced commercial jet engines. The effects of turbulence have been modeled with both algebraic and two-equation models. The results presented include steady and unsteady surface pressures, efficiencies, boundary layer quantities and turbulence quantities. The main contribution of the current work has been to show that airfoil clocking can produce significant performance variations at the Mach numbers associated with an engine operating environment. In addition, the growth of turbulence has been quantified to aid in the development of models for the multi-stage steady analyses used in design systems.

Time-marching throughflow analysis of multistage axial compressors based on a novel inviscid blade force model

2019 ◽  
Vol 233 (14) ◽  
pp. 5239-5252 ◽  
Author(s):  
Chen Yang ◽  
Hu Wu ◽  
Jinguang Yang ◽  
Michele Ferlauto
Keyword(s):  
Performance Analysis ◽  
Spline Interpolation ◽  
Guide Vane ◽  
Axial Compressor ◽  
Viscous Force ◽  
Inlet Guide Vane ◽  
Force Model ◽  
Axial Compressors ◽  
Time Marching ◽  
Throughflow Model

A time-marching throughflow method for the off-design performance analysis of axial compressors is described. The method is based on the Euler equations, and a new inviscid blade force model is proposed in order to achieve desired flow deflection. The flow discontinuity problems at the leading and trailing edges are tackled by automatic correction of blade mean surface using cubic spline interpolation. Empirical loss models have been integrated into the throughflow model in order to simulate the viscous force effects in the real three-dimensional flow. Two test cases have been presented to validate the throughflow model, including the transonic fan rotor – NASA Rotor 67 working at a near-peak-efficiency point and a 1.5-stage high-speed axial compressor with inlet guide vane operating at 68% nominal speed. Reasonable flow parameters distributions have been obtained in the Rotor 67 fan calculating results, and accurate overall performance characteristics have also been predicted at the strong off-design condition for the 1.5-stage axial compressor. The CPU time of both cases cost less than one minute at one operating point. The results indicate that the developed time-marching throughflow model is effective and efficient in the turbomachinery performance analysis.

Natural Transition Phenomena on an Axial Compressor Blade

2000 ◽  
Author(s):  
J. D. Hughes ◽  
G. J. Walker
Keyword(s):  
Guide Vane ◽  
Axial Compressor ◽  
Inlet Guide Vane ◽  
Instability Wave ◽  
Blade Loading ◽  
Instability Waves ◽  
Transition Prediction ◽  
Tollmien Schlichting ◽  
Vane Clocking ◽  
Hot Film

Data from a surface hot-film array on the outlet stator of a 1.5 stage axial compressor are analyzed to look for direct evidence of natural transition phenomena. An algorithm is developed to identify instability waves within the Tollmien Schlichting (T-S) frequency range. The algorithm is combined with a turbulent intermittency detection routine to produce space∼time diagrams showing the probability of instability wave occurrence prior to regions of turbulent flow. The paper compares these plots for a range of blade loading, with free-stream conditions corresponding to the maximum and minimum inflow disturbance periodicity produced by inlet guide vane clocking. Extensive regions of amplifying instability waves are identified in nearly all cases. The implications for transition prediction in decelerating flow regions on axial turbomachine blades are discussed.

A New Loss and Deviation Model for Axial Compressor Inlet Guide Vanes

2013 ◽  
Author(s):  
Milan Banjac ◽  
Milan V. Petrovic ◽  
Alexander Wiedermann
Keyword(s):  
Guide Vane ◽  
Thickness Distribution ◽  
Axial Compressor ◽  
Algebraic Model ◽  
Operating Conditions ◽  
Inlet Guide Vane ◽  
Viscous Effects ◽  
Through Flow ◽  
Trailing Vortices ◽  
Compressor Inlet

This paper describes a new universal algebraic model for the estimation of flow deflection and losses in axial compressor inlet guide vane devices. The model deals with nominal flow and far-off-design operating conditions in connection with large stagger angle adjustments. The first part of the model considers deflection and losses in 2D cascades, taking into account the main cascade geometry parameters and operating conditions, such as Mach number and stagger adjustment. The second part of the model deals with additional deviation and losses due to secondary flow caused by the endwall viscous effects and by the trailing vortices. The model is developed for NACA65 airfoils, NACA63-A4K6 airfoils and airfoils having an NACA65 thickness distribution on a circular-arc camber line. It is suitable for application in 1D or 2D through-flow calculations for design and analysis cases. The development of the method is based on systematic CFD flow calculations for various cascade geometries and operating parameters. The comparison of correlation results with experimental data for several test cases shows good agreement.

Wake Recovery Performance Benefit in a High-Speed Axial Compressor

2002 ◽  
Vol 124 (2) ◽  
pp. 275-284 ◽  
Author(s):  
Dale E. Van Zante ◽  
John J. Adamczyk ◽  
Anthony J. Strazisar ◽  
Theodore H. Okiishi
Keyword(s):  
High Speed ◽  
Axial Compressor ◽  
Decay Process ◽  
Operating Conditions ◽  
Rotor Wake ◽  
Stage Design ◽  
Axial Compressors ◽  
Laser Anemometer ◽  
Stretching Process ◽  
Actual Loss

Rotor wakes are an important source of loss in axial compressors. The decay rate of a rotor wake is largely due to both mixing (results in loss) and stretching (no loss accrual). Thus, the actual loss associated with rotor wake decay will vary in proportion to the amounts of mixing and stretching involved. This wake stretching process, referred to by Smith (1996) as recovery, is reversible and for a 2-D rotor wake leads to an inviscid reduction of the velocity deficit of the wake. It will be shown that for the rotor/stator spacing typical of core compressors, wake stretching is the dominant wake decay process within the stator with viscous mixing playing only a secondary role. A model for the rotor wake decay process is developed and used to quantify the viscous dissipation effects relative to those of inviscid wake stretching. The model is verified using laser anemometer measurements acquired in the wake of a transonic rotor operated alone and in a stage configuration at near peak efficiency and near stall operating conditions. Results from the wake decay model exhibit good agreement with the experimental data. Data from the model and laser anemometer measurements indicate that rotor wake straining (stretching) is the primary decay process in the stator passage. Some implications of these results on compressor stage design are discussed.

The Influence of Wake–Wake Interactions on Loss Fluctuations of a Downstream Axial Compressor Blade Row

1998 ◽  
Vol 120 (4) ◽  
pp. 695-704 ◽  
Author(s):  
G. J. Walker ◽  
J. D. Hughes ◽  
I. Ko¨hler ◽  
W. J. Solomon
Keyword(s):  
Free Stream ◽  
Guide Vane ◽  
Axial Compressor ◽  
Inlet Guide Vane ◽  
Viscous Losses ◽  
Wake Interaction ◽  
Blade Row ◽  
Wake Interactions ◽  
Periodic Fluctuations ◽  
Disturbance Field

The interaction between wakes of an adjacent rotor–stator or stator–rotor blade row pair in an axial turbomachine is known to produce regular spatial variations in both the time-mean and unsteady flow fields in a frame relative to the upstream member of the pair. This paper examines the influence of such changes in the free-stream disturbance field on the viscous losses of a following blade row. Hot-wire measurements are carried out downstream of the outlet stator in a 1.5-stage axial compressor having equal blade numbers in the inlet guide vane (IGV) and stator rows. Clocking of the IGV row is used to vary the disturbance field experienced by the stator blades; the influence on stator wake properties is evaluated. The magnitude of periodic fluctuations in ensemble-averaged stator wake thickness is significantly influenced by IGV wake-rotor wake interaction effects. The changes in time-mean stator losses appear marginal.

Aerodynamic Investigations of a Variable Inlet Guide Vane With Symmetric Profile

2014 ◽  
Author(s):  
David Händel ◽  
Reinhard Niehuis ◽  
Uwe Rockstroh
Keyword(s):  
Boundary Layer ◽  
High Speed ◽  
Guide Vane ◽  
Reynolds Numbers ◽  
Boundary Layer Transition ◽  
Inlet Guide Vane ◽  
Experimental Investigations ◽  
Wide Range ◽  
Variable Inlet Guide Vane ◽  
Symmetric Profile

In order to determine the aerodynamic behavior of a Variable Inlet Guide Vane as used in multishaft compressors, extensive experimental investigations with a 2D linear cascade have been conducted. All the experiments were performed at the High-Speed Cascade Wind Tunnel at the Institute of Jet Propulsion. They covered a wide range of Reynolds numbers and stagger angles as they occur in realistic turbomachines. Within this work at first the observed basic flow phenomena (loss development, overturning) will be explained. For the present special case of a symmetric profile and a constant decreasing chord length along the vane height, statements about different spanwise position can be made by investigating different Reynolds numbers. The focus of this paper is on the outflow of the VIGV along the vane height. Results for an open flow separation on the suction side are presented, too. Stall condition can be delayed by boundary layer control. This is done using a wire to trigger an early boundary layer transition. The outcomes of the trip wire measurement are finally discussed. The objective of this work is to evaluate the influence of the stagger angle and Reynolds number on the total pressure losses and the deviation angle. The results of the work presented here, gives a better insight of the efficient use of a VIGV.

scholarly journals Investigation on the Flow Field Entropy Structure of Non-Synchronous Blade Vibration in an Axial Turbocompressor

Entropy ◽  
2020 ◽  
Vol 22 (12) ◽  
pp. 1372
Author(s):  
Mingming Zhang ◽  
Anping Hou
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Guide Vane ◽  
Leading Edge ◽  
Inlet Guide Vane ◽  
Tip Leakage Flow ◽  
Good Correspondence ◽  
Blade Vibration ◽  
Tip Leakage ◽  
Spiral Vortex

In order to explore the inducing factors and mechanism of the non-synchronous vibration, the flow field structure and its formation mechanism in the non-synchronous vibration state of a high speed turbocompressor are discussed in this paper, based on the fluid–structure interaction method. The predicted frequencies fBV (4.4EO), fAR (9.6EO) in the field have a good correspondence with the experimental data, which verify the reliability and accuracy of the numerical method. The results indicate that, under a deviation in the adjustment of inlet guide vane (IGV), the disturbances of pressure in the tip diffuse upstream and downstream, and maintain the corresponding relationship with the non-synchronous vibration frequency of the blade. An instability flow that developed at the tip region of 90% span emerged due to interactions among the incoming main flow, the axial separation backflow, and the tip leakage vortices. The separation vortices in the blade passage mixed up with the tip leakage flow reverse at the trailing edge of blade tip, presenting a spiral vortex structure which flows upstream to the leading edge of the adjacent blade. The disturbances of the spiral vortexes emerge to rotate at 54.5% of the rotor speed in the same rotating direction as a modal oscillation. The blade vibration in the turbocompressor is found to be related to the unsteadiness of the tip flow. The large pressure oscillation caused by the movement of the spiral vortex is regarded as the one of the main drivers for the non-synchronous vibration for the present turbocompressor, besides the deviation in the adjustment of IGV.

Wall Boundary Layer Development Near the Tip Region of an IGV of an Axial Flow Compressor

1984 ◽  
Vol 106 (2) ◽  
pp. 337-345
Author(s):  
B. Lakshminarayana ◽  
N. Sitaram
Keyword(s):  
Boundary Layer ◽  
Guide Vane ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Axial Flow ◽  
Inlet Guide Vane ◽  
Wall Boundary Layer ◽  
Wall Boundary ◽  
Boundary Layer Development ◽  
Flow Compressor

The annulus wall boundary layer inside the blade passage of the inlet guide vane (IGV) passage of a low-speed axial compressor stage was measured with a miniature five-hole probe. The three-dimensional velocity and pressure fields were measured at various axial and tangential locations. Limiting streamline angles and static pressures were also measured on the casing of the IGV passage. Strong secondary vorticity was developed. The data were analyzed and correlated with the existing velocity profile correlations. The end wall losses were also derived from these data.

The Influence of Turbulence on Wake Dispersion and Blade Row Interaction in an Axial Compressor

2005 ◽  
Author(s):  
Alan D. Henderson ◽  
Gregory J. Walker ◽  
Jeremy D. Hughes
Keyword(s):  
Boundary Layer ◽  
Guide Vane ◽  
Axial Compressor ◽  
Boundary Layer Transition ◽  
Inlet Guide Vane ◽  
Grid Turbulence ◽  
Layer Transition ◽  
Free Stream Turbulence ◽  
Hot Film ◽  
Blade Element

The influence of free-stream turbulence on wake dispersion and boundary layer transition processes has been studied in a 1.5-stage axial compressor. An inlet grid was used to produce turbulence characteristics typical of an embedded stage in a multistage machine. The grid turbulence strongly enhanced the dispersion of inlet guide vane (IGV) wakes. This modified the interaction of IGV and rotor wakes, leading to a significant decrease in periodic unsteadiness experienced by the downstream stator. These observations have important implications for the prediction of clocking effects in multistage machines. Boundary layer transition characteristics on the outlet stator were studied with a surface hot-film array. Observations with grid turbulence were compared with those for the natural low turbulence inflow to the machine. The transition behavior under low turbulence inflow conditions with the stator blade element immersed in the dispersed IGV wakes closely resembled the behavior with elevated grid turbulence. It is concluded that with appropriate alignment, the blade element behavior in a 1.5-stage axial machine can reliably indicate the blade element behavior of an embedded row in a multistage machine.

Sign in / Sign up

Export Citation Format

Share Document