As future downsized boosted engines may employ multiple combustion modes, the goal of the current work is the definition of valving strategies appropriate for moderate to high load spark ignition (SI) combustion and at low to moderate loads for spark assisted compression ignition (SACI) combustion for an engine with variable valve timing capability and fixed camshaft profiles. The dilution and unburned gas temperature requirements for SACI combustion can be markedly different from those of SI; therefore it is important to ensure that a given valving strategy is appropriate for operation within both regimes. This paper compares one-dimensional (1D) thermodynamic simulations of rated engine operation with positive valve overlap (PVO) and a baseline negative valve overlap (NVO) camshaft design in a boosted automotive engine with variable valve timing capability. Several peak lifts and valve open durations are investigated to guide the down-selection of camshaft profiles for further evaluation under SACI conditions in a companion paper. While the results of this study are engine specific, rated performance predictions show that the duration of both the intake and exhaust camshafts significantly impacts the ability to achieve high load operation. While it was noted that the flow through the exhaust valves chokes for the majority of the exhaust stroke for peak exhaust lifts less than 8 mm, the aggressive engine rating of 194 kW at 5250 rpm could be achieved with peak intake lifts as low as 4 mm and baseline duration. Therefore, camshafts with peak lifts of 8/4 mm exhaust/intake were down-selected to facilitate multimode combustion operation with high levels of PVO. Analysis of high load operation with the down-selected camshafts indicates that peak unburned gas temperatures remain low enough to mitigate end-gas knock, while other variables such as peak cylinder pressure, turbine inlet temperature, and turbocharger speed are all predicted to be within acceptable limits.

References

References
1.
Olesky
,
L. M.
,
Martz
,
J. B.
,
Lavoie
,
G. A.
,
Vavra
,
J.
,
Assanis
,
D. N.
, and
Babajimopoulos
,
A.
,
2013
, “
The Effects of Spark Timing, Unburned Gas Temperature, and Negative Valve Overlap on the Rates of Stoichiometric Spark Assisted Compression Ignition Combustion
,”
Appl. Energy
,
105
, pp.
407
417
.10.1016/j.apenergy.2013.01.038
2.
Li
,
L.
,
Xie
,
H.
,
Chen
,
T.
,
Yu
,
W.
, and
Zhao
,
H.
,
2012
, “
Experimental Study on Spark Assisted Compression Ignition (SACI) Combustion With Positive Valve Overlap in a HCCI Gasoline Engine
,”
SAE
Paper No. 2012-01-1126.10.4271/2012-01-1126
3.
GT-Suite V7.2, 2011, Gamma Technologies, Inc., Westmont, IL, http://www.gtisoft.com
4.
“Engine Performance Application Manual,” Version 7.2
,
2011
, Gamma Technologies, Inc., Westmont, IL.
5.
Heywood
,
J. B.
,
1988
,
Internal Combustion Engine Fundamentals
,
McGraw-Hill
,
New York
, Vol.
930
.
6.
Ghojel
,
J. I.
,
2010
, “
Review of the Development and Applications of the Wiebe Function: A Tribute to the Contribution of Ivan Wiebe to Engine Research
,”
Int. J. Eng. Res.
,
11
(
4
), pp.
297
312
.10.1243/14680874JER06510
7.
Woschni
,
G.
,
1967
, “
A Universally Applicable Equation for the Instantaneous Heat Transfer Coefficient in the Internal Combustion Engine
,”
SAE
Paper No. 670931.10.4271/670931
8.
Chen
,
S. K.
, and
Flynn
,
P. F.
,
1965
, “
Development of a Single Cylinder Compression Ignition Research Engine
,”
SAE
Paper No. 650733.10.4271/650733
9.
Lavoie
,
G.
,
Ortiz-Soto
,
A. E.
,
Babajimopoulos
,
A.
,
Martz
,
J. B.
, and
Assanis
,
D. N.
,
2013
, “
Thermodynamic Sweet Spot for High-Efficiency, Dilute, Boosted Gasoline Engines
,”
Int. J. Eng. Res.
,
14
(
3
), pp.
260
278
.10.1177/1468087412455372
10.
Gerow
,
M. S.
,
Shingne
,
P. S.
,
Triantopoulos
,
V.
,
Bohac
,
S. V.
, and
Martz
,
J. B.
,
2014
, “
A Comparison of Valving Strategies Appropriate for Multimode Combustion Within a Downsized Boosted Automotive Engine—Part II: Midload Operation Within the SACI Combustion Regime
,”
ASME J. Eng. Gas Turbines Power
136
(
10
), p.
101509
.10.1115/1.4027360
11.
Caton
,
J. A.
,
2011
, “
Comparisons of Global Heat Transfer Correlations for Conventional and High Efficiency Reciprocating Engines
,”
ASME
Paper No. ICEF2011-60017.10.1115/ICEF2011-60017
12.
Livengood
,
J. C.
, and
Wu
,
P. C.
,
1955
, “
Correlation of Autoignition Phenomena in Internal Combustion Engines and Rapid Compression Machines
,”
Symp. (Int.) Combust.
,
5
(
1
), pp.
347–356
.10.1016/S0082-0784(55)80047-1
13.
He
,
X.
,
Donovan
,
M. T.
,
Zigler
,
B. T.
,
Palmer
,
T. R.
,
Walton
,
S. M.
,
Wooldridge
,
M. S.
, and
Atreyam
A.
,
2005
, “
An Experimental and Modeling Study of Iso-Octane Ignition Delay Times Under Homogeneous Charge Compression Ignition Conditions
,”
Combust. Flame
,
142
(
3
), pp.
266
275
.10.1016/j.combustflame.2005.02.014
14.
Babajimopoulos
,
A.
,
Prasad Challa
,
V. S. S.
,
Lavoie
,
G. A.
, and
Assanis
,
D. N.
,
2009
, “
Model-Based Assessment of Two Variable Cam Timing Strategies for HCCI Engines: Recompression vs. Rebreathing
,”
ASME
Paper No. ICES2009-76103.10.1115/ICES2009-76103
15.
Manofsky
,
L.
,
Vavra
,
J.
,
Assanis
,
D.
, and
Babajimopoulos
,
A.
,
2011
, “
Bridging the Gap Between HCCI and SI: Spark-Assisted Compression Ignition
,”
SAE
Paper No. 2011-01-1179.10.4271/2011-01-1179
16.
Lucht
,
R.
,
Richard
,
P.
,
Teets
,
E.
,
Green
,
R. M.
,
Palmer
,
R. E.
, and
Ferguson
,
C. R.
,
1987
, “
Unburned Gas Temperatures in an Internal Combustion Engine. I: CARS Temperature Measurements
,”
Combust. Sci. Technol.
,
55
(
1
), pp.
41
61
.10.1080/00102208708947070
17.
Hamamoto
,
Y.
,
Tomita
,
E.
, and
Jiang
,
D.
,
1994
, “
Temperature Measurement of End Gas Under Knocking Condition in a Spark-Ignition Engine by Laser Interferometry
,”
JSAE Rev.
,
15
(
2
), pp.
117
122
.10.1016/0389-4304(94)90021-3
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