Research Papers: Fundamental Issues and Canonical Flows

Molecular Tagging Velocimetry and Its Application to In-Cylinder Flow Measurements

[+] Author and Article Information
Ravi Vedula

e-mail: vedulara@egr.msu.edu

Mayank Mittal

e-mail: mmittal.28@gmail.com

Harold J. Schock

e-mail: schock@egr.msu.edu
Department of Mechanical Engineering,
Michigan State University,
East Lansing, MI 48824

1Present address: Generac Power Systems, S45 W29290 Wisconsin 59, Waukesha, WI 53189.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received March 19, 2013; final manuscript received July 31, 2013; published online September 19, 2013. Assoc. Editor: John Abraham.

J. Fluids Eng 135(12), 121203 (Sep 19, 2013) (17 pages) Paper No: FE-13-1175; doi: 10.1115/1.4025170 History: Received March 19, 2013; Revised July 31, 2013

This review article provides an overview of the experimental studies of in-cylinder flows using various flow measurement techniques with a focus on molecular tagging velocimetry. It is necessary to understand the evolution of large-scale and small-scale turbulence as prepared during the intake stroke with a cycle resolved quantitative description. Due to the difficulty in obtaining these descriptions, either by modeling or experimentally, they are often characterized with somewhat ambiguous notions of bulk swirl and tumble measurement methods. During the intake stroke, in-cylinder flows are formed in such a manner as to provide advantageous spatial and temporal behavior for mixture formation later during the compression stroke. Understanding the details of how these flows influence fuel-air mixing, the initiation of ignition, combustion, and subsequent flame propagation processes is the primary motivation for the development of the methods described in this paper. The authors provide an introduction to fundamental flow motion inside the engine cylinder and measurement techniques, e.g., hot-wire anemometry, laser Doppler anemometry, and particle image velocimetry. Furthermore, molecular tagging velocimetry is discussed in detail in terms of (i) different mechanisms, (ii) procedure and data reduction methods to obtain the desired flow properties such as velocity, vorticity, and turbulent intensities, and (iii) applications to flow studies in internal combustion engines. Finally, the significance of experimental investigations of in-cylinder flows is discussed along with possible future applications.

Copyright © 2013 by ASME
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Fig. 1

Biacetyl (a) phosphorescence emission spectrum and (b) absorption spectrum [60]

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Fig. 2

(a) Experimental setup for the N2O MTV, and (b) working principle of the N2O MTV showing the tagged line from the ‘write’ laser and the displaced line from the ‘read’ laser [64]

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Fig. 3

Experimental setup for the molecular tagging velocimetry [79]

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Fig. 4

(a) Calibration object with spotted circles for mapping, and (b) corresponding MTV images from the left and right cameras [72]

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Fig. 5

Undelayed (left) and delayed (right) MTV sample images with the source (solid squares) and roam (dashed square) windows highlighted (adapted from Gendrich and Koochesfahani [65])

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Fig. 6

–(left) A template with all of the relevant characteristics, and –(right) superposition of this sample on an MTV grid node having different intensities [51]

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Fig. 7

Template matching concept [51]

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Fig. 8

A typical stereoscopic MTV experimental setup [72]

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Fig. 9

Two basic configurations for stereoscopic imaging: (a) lens translation, and (b) angular displacement [75]

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Fig. 10

Comparison of the translation method with the angular displacement method

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Fig. 11

Instantaneous velocity fields showing unsteadiness near the intake valve of a steady flow rig model (adapted from Stier and Koochesfahani [60])

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Fig. 12

Tumble port blocker (left), and swirl port blocker (right) [76]

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Fig. 13

Normalized circulation on the tumble plane (top), and the swirl plane (bottom) during the compression stroke using different intake ports [76]

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Fig. 14

Ensemble-averaged velocity vectors, contours of velocity rms for no CMCV (left), and CMCV applied (right) at the intake (171 CAD) and compression (221 CAD) strokes on the swirl plane [79]

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Fig. 15

Ensemble-averaged velocity and out-of-plane mean vorticity at 270 CAD [72]

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Fig. 16

Velocities (rms) at 270 CAD [72]

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Fig. 17

(a) Conventional MTV grid formation, and (b) alternate method to study flow details near the wall and in the spark plug area [80]

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Fig. 18

Mean and rms velocities along the swirl plane at (from left) 40 kPa, 50 kPa, and 80 kPa inlet manifold pressures [81]

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Fig. 19

Sapphire cylinder liner with the steel ring attached

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Fig. 20

Optical engine setup (left), and the new optical cylinder liner attached to the cylinder head of an overhead cam diesel engine




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