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TECHNICAL PAPERS: Internal Combustion Engines

# Prediction of Peak Cylinder Pressure Variations Over Varying Inlet Air Condition of Compression-Ignition Engine

[+] Author and Article Information
Gong Chen

Department of Mechanical Engineering, Gannon University, Erie, PA 16541

J. Eng. Gas Turbines Power 129(2), 589-595 (Aug 15, 2006) (7 pages) doi:10.1115/1.2431389 History: Received September 30, 2005; Revised August 15, 2006

## Abstract

Peak cylinder pressure $(pmax)$ of a compression-ignition engine can be affected by the engine inlet air condition, such as its inlet air temperature $(Ti)$ and pressure $(pi)$. The variation of peak cylinder pressure due to varying inlet air temperature or pressure is analytically studied. A model is developed and simplified, and thus the variations of $pmax$ can be predicted along with varying inlet air temperature or pressure. The analysis and prediction indicate that cylinder active compression ratio (CR) and intake air boost ratio $(pm0∕pi0)$ play relatively significant roles in affecting the variation of $pmax$ over inlet air temperature and pressure, and the pressure variation is proportional to $CRk$ and ratio $pm0∕pi0$. Comparison between the predicted results using the simplified model and those from engine experiments shows a close agreement in both the trend and magnitude. The investigation and prediction also include modeling the variation in $pmax$ due to varying the cylinder TDC clearance volume $(Vc)$. The simplified model is presented and shows that the change in $pmax$ versus varying $Vc$ also depends on the cylinder compression ratio. It is indicated that for a certain change in the clearance volume, a higher compression-ratio configuration would produce a greater change in $pmax$ than a lower one does, especially as the rest of the engine design and operating parameters remain unchanged.

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## Figures

Figure 1

Illustration of peak cylinder pressure

Figure 2

Comparison of predicted Δpmax between using model and simplified model (k=1.32, n=0.8, CR=15, pm0=0.32MPa)

Figure 3

Predicted pmax-variation rate over inlet air temperature at various compression ratio (k=1.32, n=0.8)

Figure 4

Predicted Δpmax∕pm0 versus inlet air temperature at various compression ratio (k=1.32, n=0.8)

Figure 5

Predicted change in pmax versus intake air boost ratio at various inlet air temperature (k=1.32, n=0.8, CR=15)

Figure 6

Predicted and measured change in pmax versus inlet air temperature of engine

Figure 7

Predicted rate of variation of pmax over inlet air pressure at various compression ratio (k=1.32, m=0.4, pm0∕pi0=3.2)

Figure 8

Predicted change in pmax versus inlet air pressure at various compression ratio (k=1.32, m=0.4, pm0∕pi0=3.2)

Figure 9

Predicted change in pmax over air boost ratio and inlet air pressure (k=1.32, m=0.4, CR=15)

Figure 10

Predicted and measured change in pmax versus inlet air pressure of engine

Figure 11

Predicted variation of pmax over cylinder TDC volume at various compression ratio

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