Turbulence Measurements at the Inlet of an Automotive Turbocharger Compressor using Stereoscopic Particle Image Velocimetry

2021 ◽  
pp. 1-50
Author(s):  
Deb Banerjee ◽  
Rick Dehner ◽  
Ahmet Selamet
Keyword(s):  
Particle Image Velocimetry ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Mass Flow ◽  
Particle Image ◽  
Stereoscopic Particle Image Velocimetry ◽  
Flow Rates ◽  
Image Velocimetry ◽  
Compressor Inlet ◽  
The Mean

Abstract The present work uses Stereoscopic Particle Image Velocimetry (SPIV) to analyze the compressor inlet flow field, with specific emphasis on its turbulence characteristics during flow reversal in order to gain further insight into the inlet flow structures. SPIV experiments were carried out at the inlet of a centrifugal compressor without any recirculation channel at four different rotational speeds (from 80 to 140 krpm) and over the entire mass flow range (from choke to surge) at each speed. Detailed analyses have been carried out for the mean velocity field, the mean vorticity field, and the turbulent statistics including turbulent kinetic energy, Reynolds stress, and the one-dimensional energy spectra. The turbulent kinetic energy at the compressor inlet was observed to increase rapidly along a speed line with decreasing mass flow rate once flow separation started, and the turbulence became more anisotropic. As the flow rate was reduced (along a speed line), the zone with maximum turbulent kinetic energy moved from the periphery toward the center of the inlet duct and also occurred further upstream from the impeller. The Reynolds stress distributions suggest that the Boussinesq assumption of an isotropic eddy viscosity may not be appropriate after the detection of flow reversal. The Reynolds shear stresses were observed to change signs with their corresponding velocity gradients at the tested mass flow rates at different rotational speeds. At the investigated flow rates, the radial gradients in the axial and tangential velocities were found to be most dominant.

Scaled Room Three-Dimensional Velocity Measurements Using Particle Image Velocimetry

2002 ◽  
Author(s):  
Steven P. O’Halloran ◽  
B. Terry Beck ◽  
Mohammad H. Hosni ◽  
Thomas P. Gielda
Keyword(s):  
Particle Image Velocimetry ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Particle Image ◽  
Three Dimensional ◽  
Stereoscopic Particle Image Velocimetry ◽  
Measurement Information ◽  
Velocity Measurements ◽  
Image Velocimetry ◽  
Equipment Configuration

A stereoscopic particle image velocimetry (PIV) system was used to measure flow within a one-tenth-scale room. The dimensions of the scaled room were 732 × 488 × 274 mm (28.8 × 19.2 × 10.8 in.). The measurements were made under isothermal conditions and water was used as the fluid instead of air. Six equally spaced vertical planes along the length of the room were captured and symmetry was utilized so that measurements were only made on one side of the room. A sample size of 50 pairs of PIV images were collected and averaged to determine average velocity. Turbulent kinetic energy was also calculated from the collected data. The equipment configuration, measurement information and the velocity and turbulent kinetic energy results are presented in this paper. The measurements provide detailed three dimensional velocity profiles that could be used to validate numerical simulations.

Investigation of Cross-Sectional Velocity Field Near the Inducer Plane of a Turbocharger Compressor Using 2D Particle Image Velocimetry

2019 ◽  
Author(s):  
Deb Banerjee ◽  
Rick Dehner ◽  
Ahmet Selamet ◽  
Keith Miazgowicz ◽  
Todd Brewer ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Velocity Field ◽  
Flow Field ◽  
Mass Flow ◽  
Particle Image ◽  
Tangential Velocity ◽  
Cross Sectional ◽  
Flow Rates ◽  
Blade Passage ◽  
Image Velocimetry

Abstract Understanding the velocity field at the inlet of an automotive turbocharger is critical in order to suppress the instabilities encountered by the compressor, extend its map and improve the impeller design. In the present study, two-dimensional particle image velocimetry experiments are carried out on a turbocharger compressor without any recirculating channel to investigate the planar flow structures on a cross-sectional plane right in front of the inducer at a rotational speed of 80 krpm. The objective of the study is to investigate the flow field in front of a compressor blade passage and quantify the velocity distributions along the blade span for different mass flow rates ranging from choke (77 g/s) to deep surge (13.6 g/s). It is observed that the flow field does not change substantially from choke to about 55 g/s, where flow reversal is known to start at this speed from earlier measurements. While the tangential velocity is less than 8 m/s, the radial velocity increases along the span to 17–20 m/s near the tip at high flow rates (55–77 g/s). As the mass flow rate is reduced below 55 g/s, the radial component starts decreasing and the tangential velocity increases rapidly. From about 5 m/s at 55 g/s, the tangential velocity at the blade tip exceeds 50 m/s at 50 g/s and reaches a maximum of about 135 m/s near surge. These time-averaged distributions are similar for different angular locations in front of the blade passage and do not exhibit any substantial azimuthal variation.

Experimental Investigation of Unsteady Flow Field Within a Two Stage Axial Turbomachine Using Particle Image Velocimetry

2002 ◽  
Author(s):  
Oguz Uzol ◽  
Yi-Chih Chow ◽  
Joseph Katz ◽  
Charles Meneveau
Keyword(s):  
Particle Image Velocimetry ◽  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Particle Image ◽  
Energy Levels ◽  
Shear Stresses ◽  
Image Velocimetry ◽  
Entire Flow ◽  
The Difference

Detailed measurements of the flow field within the entire 2nd stage of a two stage axial turbomachine are performed using Particle Image Velocimetry. The experiments are performed in a facility that allows unobstructed view on the entire flow field, facilitated using transparent rotor and stator and a fluid that has the same optical index of refraction as the blades. The entire flow field is composed of a “lattice of wakes”, and the resulting wake-wake and wake-blade interactions cause major flow and turbulence non-uniformities. The paper presents data on the phase averaged velocity and turbulent kinetic energy distributions, as well as the average-passage velocity and deterministic stresses. The phase-dependent turbulence parameters are determined from the difference between instantaneous and the phase-averaged data. The distributions of average-passage flow field over the entire stage in both the stator and rotor frames of reference are calculated by averaging the phase-averaged data. The deterministic stresses are calculated from the difference between the phase-averaged and average-passage velocity distributions. Clearly, wake-wake and wake-blade interactions are the dominant contributors to generation of high deterministic stresses and tangential non-uniformities, in the rotor-stator gap, near the blades and in the wakes behind them. The turbulent kinetic energy levels are generally higher than the deterministic kinetic energy levels, whereas the shear stress levels are comparable, both in the rotor and stator frames of references. At certain locations the deterministic shear stresses are substantially higher than the turbulent shear stresses, such as close to the stator blade in the rotor frame of reference. The non-uniformities in the lateral velocity component due to the interaction of the rotor blade with the 1st stage rotor-stator wakes, result in 13% variations in the specific work input of the rotor. Thus, in spite of the relatively large blade row spacings in the present turbomachine, the non-uniformities in flow structure have significant effects on the overall performance of the system.

Estimation of Turbulent Length Scales at a Turbocharger Inlet Using Particle Image Velocimetry

2021 ◽  
Author(s):  
Deb Banerjee ◽  
Ahmet Selamet ◽  
Rick Dehner
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Operating Conditions ◽  
Stereoscopic Particle Image Velocimetry ◽  
Length Scales ◽  
Image Velocimetry ◽  
Fundamental Understanding ◽  
Compressor Inlet ◽  
Kolmogorov Scale

Abstract Stereoscopic Particle Image Velocimetry measurements are carried out at the inlet of a turbocharger compressor at four different shaft speeds from 80,000 rpm to 140,000 rpm and over the entire range of flow rates from choke to mild surge. This paper describes the procedure used in processing the PIV data leading to the estimates of turbulent length scales – integral, Taylor, and Kolmogorov, to enhance the fundamental understanding and characterization of the compressor inlet flow field. The analysis reveals that at most operating conditions the three different length scales have markedly different magnitudes, as expected, while they have somewhat similar qualitative distributions with respect to the duct radius. For example, at 80,000 rpm and at a flow rate of 15.7 g/s (mild surge), the longitudinal integral length scale is of the order of 15 mm, the Taylor scale is around 0.5 mm, and the Kolmogorov scale is about 10 microns. With the onset of flow reversal, the turbulent kinetic energy and turbulent intensity at the compressor inlet are observed to increase rapidly, while the magnitudes of the Kolmogorov scale and to a certain extent, the Taylor scale are found to decrease suggesting that the increased turbulence gives rise to even smaller flow structures. The variation of length scales with compressor shaft speed has also been studied.

Convergence of PIV Measurements at the Inlet of a Turbocharger Compressor

2019 ◽  
Author(s):  
Deb Banerjee ◽  
Ahmet Selamet ◽  
Rick Dehner ◽  
Keith Miazgowicz
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Field ◽  
Turbulent Flow ◽  
Coefficient Of Variation ◽  
Particle Image ◽  
Flow Fields ◽  
Statistical Moment ◽  
Stereoscopic Particle Image Velocimetry ◽  
Image Velocimetry ◽  
The Mean

Abstract Particle Image Velocimetry has become a desirable tool to investigate turbulent flow fields in different engineering applications, including flames, combustion engines, and turbomachinery. The convergence characteristics of turbulent statistics of these flow fields are of prime importance since they help with the number of images (temporally uncorrelated) to be captured in order for the results to converge to a certain tolerance or with the assessment of the uncertainty of the measurements for a given number of images. The present work employs Stereoscopic Particle Image Velocimetry to examine the turbulent flow field at the inlet of an automotive turbocharger compressor without any recirculating channel. Optical measurements were conducted at five different mass flow rates spanning from choke to surge at a corrected rotational speed of 80 krpm. The velocity fields thus obtained were used to analyze the convergence of the mean (first statistical moment) and variance (second statistical moment) at different operating conditions. The convergence of the mean at a particular location in the flow field depends on the local coefficient of variation (COV). The number of required images for the mean to converge to a particular tolerance was also found to follow roughly a linear trend with respect to COV. While the convergence of the variance, on the other hand, did not appear to show any direct dependence on the coefficient of variation, it takes significantly more images than the mean to converge to the same level of tolerance.

scholarly journals Turbulent kinetic energy and self-sustaining tones: Experimental study of a rectangular impinging jet using high Speed 3D tomographic Particle Image Velocimetry

2020 ◽  
Vol 14 (1) ◽  
pp. 6322-6333
Author(s):  
Hassan Hasan Assoum ◽  
Jana Hamdi ◽  
Mouhammad El Hassan ◽  
Kamel Abed-Meraim ◽  
M. El Kheir ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Energy Transfer ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Acoustic Signal ◽  
Particle Image ◽  
Tomographic Particle Image Velocimetry ◽  
Rectangular Jet ◽  
Image Velocimetry ◽  
Slotted Plate

Impinging jets are widely used in ventilation systems to improve the mixing and diffusion of airflows. When a rectangular jet hits a slotted plate, an acoustic disturbance can be generated and self-sustained tones produced. Few studies have looked at the Turbulent Kinetic Energy (TKE) produced by the aerodynamic field in such configurations and in the presence of self-sustaining tones. The aim of this work is to investigate the energy transfer between the aerodynamic and acoustic fields generated in a rectangular jet impinging on a slotted plate. The present paper methodology is based on experimental data measurements using 3D tomographic Particle Image Velocimetry (PIV) technique and microphones. It was found that the spectrum of the TKE for Re=5294 (configuration of self-sustained tones) is    which is smaller than that of the acoustic signal . A negative peak of correlation  is obtained between the acoustic signal and TKE for   These results may lead to conclude that the acoustic cycle should be covered by the TKE period and the two signals of both fields are in opposition of phase in order to obtain an optimal configuration for energy transfer.

Estimation of Turbulent Length Scales at a Turbocharger Inlet using Stereoscopic Particle Image Velocimetry

2022 ◽  
Author(s):  
Deb Banerjee ◽  
Ahmet Selamet ◽  
Rick Dehner
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Operating Conditions ◽  
Stereoscopic Particle Image Velocimetry ◽  
Length Scales ◽  
Image Velocimetry ◽  
Fundamental Understanding ◽  
Compressor Inlet ◽  
Kolmogorov Scale

Abstract Stereoscopic Particle Image Velocimetry measurements are carried out at the inlet of a turbocharger compressor at four different shaft speeds from 80,000 rpm to 140,000 rpm and over the entire range of flow rates from choke to mild surge. This paper describes the procedure used in processing the PIV data leading to the estimates of turbulent length scales - integral, Taylor, and Kolmogorov, to enhance the fundamental understanding and characterization of the compressor inlet flow field. The analysis reveals that at most operating conditions the three different length scales have markedly different magnitudes, as expected, while they have somewhat similar qualitative distributions with respect to the duct radius. For example, at 80,000 rpm and at a flow rate of 15.7 g/s (mild surge), the longitudinal integral length scale is of the order of 15 mm, the Taylor scale is around 0.5 mm, and the Kolmogorov scale is about 10 microns. With the onset of flow reversal, the turbulent kinetic energy and turbulent intensity at the compressor inlet are observed to increase rapidly, while the magnitudes of the Kolmogorov scale and to a certain extent, the Taylor scale are found to decrease suggesting that the increased turbulence gives rise to even smaller flow structures. The variation of length scales with compressor shaft speed has also been studied.

Experimental Investigation of Unsteady Flow Field Within a Two-Stage Axial Turbomachine Using Particle Image Velocimetry

2002 ◽  
Vol 124 (4) ◽  
pp. 542-552 ◽  
Author(s):  
Oguz Uzol ◽  
Yi-Chih Chow ◽  
Joseph Katz ◽  
Charles Meneveau
Keyword(s):  
Particle Image Velocimetry ◽  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Particle Image ◽  
Energy Levels ◽  
Shear Stresses ◽  
Image Velocimetry ◽  
Entire Flow ◽  
The Difference

Detailed measurements of the flow field within the entire 2nd stage of a two-stage axial turbomachine are performed using particle image velocimetry. The experiments are performed in a facility that allows unobstructed view on the entire flow field, facilitated using transparent rotor and stator and a fluid that has the same optical index of refraction as the blades. The entire flow field is composed of a “lattice of wakes,” and the resulting wake-wake and wake-blade interactions cause major flow and turbulence nonuniformities. The paper presents data on the phase averaged velocity and turbulent kinetic energy distributions, as well as the average-passage velocity and deterministic stresses. The phase-dependent turbulence parameters are determined from the difference between instantaneous and the phase-averaged data. The distributions of average passage flow field over the entire stage in both the stator and rotor frames of reference are calculated by averaging the phase-averaged data. The deterministic stresses are calculated from the difference between the phase-averaged and average-passage velocity distributions. Clearly, wake-wake and wake-blade interactions are the dominant contributors to generation of high deterministic stresses and tangential nonuniformities, in the rotor-stator gap, near the blades and in the wakes behind them. The turbulent kinetic energy levels are generally higher than the deterministic kinetic energy levels, whereas the shear stress levels are comparable, both in the rotor and stator frames of references. At certain locations the deterministic shear stresses are substantially higher than the turbulent shear stresses, such as close to the stator blade in the rotor frame of reference. The nonuniformities in the lateral velocity component due to the interaction of the rotor blade with the 1st-stage rotor-stator wakes, result in 13 percent variations in the specific work input of the rotor. Thus, in spite of the relatively large blade row spacings in the present turbomachine, the nonuniformities in flow structure have significant effects on the overall performance of the system.

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