Laser Doppler anemometer measurements of mean velocity and turbulence in internal combustion engines

This study was carried out to assess the ability of a computational fluid dynamics (CFD) code to predict the scavenging flow in the cylinder of a two-stroke cycle engine. Predictions were obtained from a CFD simulation of the flow within the cylinder. Due to the apparent sym-metry of the engine port layout, only half of the cylinder volume was modelled. Boundary conditions for the CFD model were obtained from experimentally measured pressure-time histories in the crankcase and exhaust. The two-stroke cycle engine was modified to allow laser Doppler velocimetry (LDV) measurements to be made of the in-cylinder flow. The engine was operated under motoring conditions at 500 r/min with a delivery ratio of 0.7. Although the engine scavenge port layout was geometrically symmetrical, an asymmetrical flow field was identified in the cylinder. As a result of this, a direct comparison of the in-cylinder LDV measured and CFD computed results was not possible. However, LDV and CFD results for the in-cylinder flow are presented to help highlight the dissimilarity between the measured and predicted flow fields. Two-dimensional LDV measurements were made in the cylinder at the transfer ports for a portion of the cycle. A comparison of these LDV measurements with CFD predictions of the in-cylinder velocities at the same locations showed that the CFD model could replicate reasonably well the general trend of the flow. The measured cylinder averaged turbulent kinetic energy was compared with that of the CFD model. The qualitative trend of the overall turbulence generating capacity of the engine was well replicated by the CFD model.

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“…The characterization of in-cylinder turbulence from LDV data may be found in several references (e.g. references [36], [37] and [38]).…”

Section: In-cylinder Turbulencementioning

confidence: 99%

Laser Doppler velocimetry measurements of flow within the cylinder of a motored tow-stroke cycle engine-comparison with some computational fluid dynamics predictions

Creaven

Fleck

Kenny

et al. 2003

International Journal of Engine Research

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“…The LDV technique was widely adopted all over the world. The most representative studies are for examples: Liou et al [6], Rask [8], Klick et al [5], Arcoumanis et al [1], Obokata et al [7] etc. in the U.S., Europe and Japan.…”

Section: Introductionmentioning

confidence: 99%

Parametric studies of in‐cylinder pre‐combustion turbulence of a transparent engine using FLDV

Hong¹,

Tzeng²

1996

Journal of the Chinese Institute of Engineers

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This paper uses a 3-D fiber laser Doppler velocimeter (FLDV) to measure the turbulent flow field inside a pancake type combustion chamber of a four-stroke single cylinder transparent engine. Three components of the instantaneous flow velocity at the central point on a plane 10 mm below the cylinder head are obtained to characterize the flow field before combustion. The experiment employed a filtering method to resolve the high frequency turbulence and low frequency cyclic fluctuation from the instantaneous velocity data. In addition, a temporal autocorrelation coefficient, integral time and length scales, and a normalized power spectral density function are also calculated to characterize the turbulence structure. Variations of parameters, such as compression ratio and engine speed, are carried out in the experiment to study the effects of the design factor and the operation parameter on the characteristics of the in-cylinder flow field.

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“…The outer stationary cylinder was not painted because it was important to clearly see through it and check the movement of the laser beams in the flow cell, as well as the progress of the experiment with time. Also, the method of Rask (1984) was tested; a black circular mask, also known as "obscuration disc", of no more than 0.5" diameter (made of black electrical tape) was placed in the center of the collection lens. This resulted in a reduction of the amount of scattered light reaching the PMT from the wall, since the depth of the field of the collection lens was reduced (Eckbreth & Davis, 1977).…”

Section: Steady Streaming With Watermentioning

confidence: 99%

Rheological Characterization of Drag-Reducing Fluids

Βλασσοπουλοσ¹

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for his unfailing support and friendship throughout the course of this work. His approach to science and his deep physical intuition will undoubtly influence me throughout all my career. I truly appreciate his concern, understanding, and encouragement, especially during the difficult moments of my stay in Princeton.Many thanks to my second reader, Professor Robert K. Prud'homme, for his genuine interest and useful suggestions, and for the long-term loan of several TSI components. I am indebted to Professor William W. Graessley for his help with the characterization of the polymers, and for giving me the opportunity to perform some important measurements at Exxon. Special mention goes out to Professor William B. Rüssel for his help with important non-technical matters. I would like to acknowledge the entire staff of the department for its support. Special thanks to Peggy Pearce and Betty Bixby for their help with administrative matters, and to Archie Harkness for machining several parts of my apparatus.Outside of the department, I wish to especially thank Professor Alexander J. Smits, in Mechanical and Aerospace Engineering, for his enthusiastic support, and for offering me to use the space and facilities of the Gas Dynamics Laboratory, in Forrestal Campus, in order to perform my experiments. Professor Behrouz Chehroudi, from the University of Illinois at Chicago, helped me a lot with the LDV signal processing, and ν let me use his data acquisition program. Dr. Man Won Kim and Mr. Robert W. Thomas, both from Exxon, have been extremely helpful with the molecular weight and shear viscosity measurements. Professor Antony N. Beris, from the University of Delaware, made helpful suggestions and was always generous with his time. Professor Daniel C. Tsui, in Electrical Engineering, is thanked for the long-term loan of his electromagnet. Several improvements to this thesis are the result of long discussions with my groupmates. Thanks to Martin Wittmann, Dave Davidson, Fred Lim, Frank Torres, Gary Christensen, Mike Koerner, and Rick Mifflin. I would like to especially thank Martin and Dave. The solutions preparation, construction of drag reduction apparatus, and the Exxon experiments, have all been results of a joint effort with Martin, who also answered several questions about UNDC during the after hours. Dave helped me use his nonlinear fitting and IBM plotting routines, and discussed with me numerous topics in non-Newtonian fluid mechanics during coffee breaks. I am particularly grateful to Yiannis Dimitratos for his friendship, for several great weekends together, and for lending me his camera indefinitely. Many thanks to my good friends Dave & Dawn Davidson (for several great evenings, and for convincing me that cows are intelligent), Martin Wittmann (for six years of common experiences in the CAVE), and Stelios Tsinontides (for our numerous discussions, ranging from chemical engineering to presidential politics), and also to Prabhu Nott,

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Laser Doppler anemometer measurements of mean velocity and turbulence in internal combustion engines

Cited by 19 publications

References 43 publications

Laser Doppler velocimetry measurements of flow within the cylinder of a motored tow-stroke cycle engine-comparison with some computational fluid dynamics predictions

Laser Doppler velocimetry measurements of flow within the cylinder of a motored tow-stroke cycle engine-comparison with some computational fluid dynamics predictions

Parametric studies of in‐cylinder pre‐combustion turbulence of a transparent engine using FLDV

Rheological Characterization of Drag-Reducing Fluids

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