Further investigation of the turbulence time-frequency spectral structure and its anisotropy and nonhomogeneity has been carried out in the combustion chamber of an automotive diesel engine with a high-squish reentrant in-piston-bowl and a helical intake port. An advanced HWA technique was applied for turbulence measurements along the injector axis, under motored engine conditions in the speed range of 600–3000 rpm. Autospectral density functions of each fluctuating velocity component, as was determined by a specific sensor-wire orientation, were evaluated in consecutive crank-angle correlation intervals during the induction, compression, and early expansion strokes. In order to study the speed dependence of the turbulence-structure anisotropy and nonhomogeneity in different portions of the engine cycle, time-scales of cycle-resolved and conventional turbulent fluctuations were analyzed as functions of the engine speed for different wire orientations, measurement locations, and correlation intervals. Anisotropy and nonhomogeneity were generally significant at low engine speeds, whereas a tendency towards isotropy and homogeneity was found by increasing the speed. With specific reference to the bowl-generated turbulence, spectral anisotropy was remarkable at all speeds in the reverse-squish flow, close to the cylinder-head wall. However, spectral nonhomogeneity was the main feature of the direct-squish flow at low engine speeds.

1.
Bazari, Z., 1992, “A DI Diesel Combustion and Emission Predictive Capability for Use in Cycle Simulation,” SAE Paper No. 920462.
2.
Bendat, J. S., and Piersol, A. G., 1986, Random Data: Analysis and Measurement Procedures, 2nd Ed., John Wiley & Sons, New York.
3.
Catania, A. E., 1985, “Induction System Effects on the Fluid-Dynamics of a D.I. Automotive Diesel Engine,” ASME Paper No. 85-DGP-ll.
4.
Catania
A. E.
, and
Mittica
A.
,
1989
, “
Extraction Techniques and Analysis of Turbulence Quantities from In-Cylinder Velocity Data
,”
ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER
, Vol.
111
, pp.
466
478
.
5.
Catania
A. E.
, and
Mittica
A.
,
1990
, “
Autocorrelation and Autospectra Estimation of Reciprocating Engine Turbulence
,”
ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER
, Vol.
112
, pp.
357
368
.
6.
Catania
A. E.
,
Dongiovanni
C.
, and
Mittica
A.
,
1992
a, “
Time-Frequency Spectral Structure of Turbulence in an Automotive Engine
,” Paper No. 920153.
Journal of Engines
, SAE, Vol.
101
, pp.
221
244
.
7.
Catania, A. E., Dongiovanni, C, Mittica, A., Molina, G., and Spessa, E., 1994, “Cycle-Resolved HWA Measurements with Single and Dual-Sensor Probes in an Open-Chamber Automotive Engine,” Proceedings, COMODIA 94, JSME, Tokyo, pp. 437–444.
8.
Catania
A. E.
,
Dongiovanni
C.
,
Mittica
A.
,
Molina
G.
, and
Spessa
E.
,
1995
, “
A New Test Bench for HWA Fluid-Dynamic Characterization of a Two-Valved In-Piston-Bowl Production Engine
,” Paper No. 952467,
Journal of Engines
, SAE, Vol.
104
, Sect. 3, pp.
2301
2324
.
9.
Catania
A. E.
, and
Spessa
E.
,
1996
, “
Speed Dependence of Turbulence Properties in a High-Squish Automotive Engine Combustion System
,” SAE Paper No. 960268,
Journal of Engines
, SAE, Vol.
105
, Sect. 3, pp.
313
334
.
10.
Catania
A. E.
,
Dongiovanni
C.
,
Mittica
A.
,
Negri
C.
, and
Spessa
E.
,
1996
, “
Turbulence Spectrum Investigation in a DI Diesel Engine With a Reentrant Combustion Bowl and a Helical Inlet Port
,” SAE Paper No. 962019.
Journal of Engines
, SAE, Vol.
105
, Sect. 3, pp.
2205
2226
.
11.
Daneshyar
H.
, and
Hill
P. G.
,
1987
, “
The Structure of Small-Scale Turbulence and Its Effect on Combustion in Spark Ignition Engines
,”
Prog. Energy Combust. Sci.
, Vol.
13
, pp.
47
73
.
12.
Floch, A., Van Frank, J., and Ahmed, A., 1995, “Comparison of the Effects of Intake-Generated Swirl and Tumble on Turbulence Characteristics in a 4-Valve Engine,” SAE Paper No. 952457, Diagnostics in Diesel and SI Engines, SAE SP-1122, pp. 69–85.
13.
Heywood, J. B., 1988, Internal Combustion Engine Fundamentals, McGraw-Hill International Editions, New York.
14.
Ikegami, M., 1990, “Role of Flows and Turbulent Mixing in Combustion and Pollutant Formation in Diesel Engines,” Proceedings, COMODIA 90, JSME, Tokyo, pp. 49–58.
15.
Konno, M., Chikahisa, T., and Murayama, T., 1992, “Reduction of Smoke and NOx by Strong Turbulence Generated During the Combustion Process in D.I. Diesel Engines,” SAE Paper No. 920467, Reducing Emissions from Diesel Combustion, SAE SP-895, pp. 111–119.
16.
Lancaster
R. D.
,
Krieger
R. B.
,
Sorenson
S. C.
, and
Hull
W. L.
,
1976
, “
Effects of Turbulence on Spark-Ignition Engine Combustion
,” Paper No. 760160,
Trans. SAE
, Vol.
85
, pp.
689
710
.
17.
Lesieur, M., 1987, Turbulence in Fluids, Martinus Nijhoff Publishers, The Netherlands.
18.
Magnussen, B. F., and Hjertager, B. H., 1976, “On Mathematical Modelling of Turbulent Combustion With Special Emphasis on Soot Formation and Combustion,” paper presented at the 16th Symposium (International) on Combustion, The Combustion Institute, Pittsburg, PA.
19.
Plee, S. L., and Ahmad, T., 1983, “Relative Roles of Premixed and Diffusion Burning in Diesel Combustion,” SAE Paper No. 831733.
20.
Rabiner, L. R., Schafer, R. W., and Dlugos, D., 1979, “Correlation Method for Power Spectrum Estimation,” IEEE Programs for Digital Signal Processing, IEEE, Piscataway, NJ.
21.
Rader
C. M.
,
1970
, “
An Improved Algorithm for High Speed Autocorrelation with Applications to Spectral Estimation
,”
IEEE Trans. Audio Electroacustics
, Vol.
AU-18
, No.
4
, pp.
439
441
.
22.
Smith
W. J.
, and
Timoney
D. J.
,
1997
, “
On the Relative Roles of Fuel Spray Kinetic Energy and Engine Speed in Determining Mixing Rates in D.I. Diesel Engines
,”
ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER
, Vol.
119
, pp.
212
217
.
23.
Spessa, E., 1995, “Experimental Investigation of Turbulent Flow Properties in a Diesel Engine Cylinder by an Innovative HWA Technique,” (in Italian) Ph.D. thesis, Politecnico di Torino.
24.
Spessa, E., 1997, “A Contribution to the Analysis of Turbulence Anisotropy and Nonhomogeneity in an Open-Chamber Diesel Engine,” ICE-Vol. 29-2, Book. No. H1099B.
25.
Timoney, D. J., and Smith, W. J., 1996, “Influences of Fuel Injection and Air Motion Energy Sources on Fuel-Air Mixing Rates in a D.I. Diesel Combustion System,” SAE Paper No. 960035, Diesel Engine Combustion Processes, SAE SP-1159, pp. 89–101.
26.
Witze, P. O., 1994, “In-Cylinder Diagnostics for Production Spark-Ignition Engines,” in Unsteady Combustion, F. E. Culick, M. V. Heitor, and J. H. Whitelaw, Eds., Kluwer Academic Publishers, Dordrecht, The Netherlands.
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