Simulation Study of Injection Strategy and Tumble Effect on the Mixture Formation and Spray Impingement in a Gasoline Direct Injection Engine

2014 ◽  
Author(s):  
Song Han ◽  
Jing Qin ◽  
Manqun Lin ◽  
Yanrong Li ◽  
Yidan Zhang
Keyword(s):  
Simulation Study ◽  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Mixture Formation ◽  
Injection Strategy ◽  
Direct Injection Engine ◽  
Gasoline Direct Injection Engine ◽  
Spray Impingement

Influences of the fuel injection parameters on the first-cycle firing and the combustion characteristics during the direct-start process for a gasoline direct-injection engine

2016 ◽  
Vol 231 (5) ◽  
pp. 585-599 ◽  
Author(s):  
Fangxi Xie ◽  
Yan Su ◽  
Wei Hong ◽  
Xiangyu Li ◽  
Xiaoping Li ◽  
...  
Keyword(s):  
Heat Release ◽  
Single Injection ◽  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Injection Strategy ◽  
Fuel Mass ◽  
Direct Injection Engine ◽  
Gasoline Direct Injection Engine ◽  
Dual Injection ◽  
Start Process

The direct-start method without requiring a starter is a viable and cost-effective solution for generating a frequent and efficient restarting process when start–stop technology is used on a gasoline direct-injection engine. During the direct-start process, the first-cycle combustion characteristics play a key role in determining whether the start mode is successful or not, because the start energy is wholly derived from the in-cylinder combustion without the support of a starter motor on the gasoline direct-injection engine. However, the first-cycle fuel–air mixing and combustion characteristics during the direct-start process of a gasoline direct-injection engine are not fully understood. In this work, the influences of the injection parameters, including the delay between the injection and ignition, the excess air ratio for the single-injection strategy, the delay between the first injection and the second injection for the dual-injection strategy and the ratio of the fuel mass in the first injection to the fuel mass in the second injection for the dual-injection strategy, on the combustion pressure, the heat release rate, the accumulated heat release and the indicated work were investigated experimentally by cycle-by-cycle analysis. The results show that the optimal delay between the injection and ignition of the single-injection strategy was 200 ms as a longer delay or a shorter delay can result in a reduction in the heat released rate, the indicated work and the firing boundary. A shorter delay with the optimal injected fuel mass tended to be more beneficial to the accumulated heat released, the indicated work and the crankshaft speed. Furthermore, with increasing delay and increasing fuel ratio of the fuel mass in the first injection to the fuel mass in the second injection for the dual-injection strategy, the heat release rate, the accumulated heat release and the indicated work first increased and then decreased. The optimum delay was 10 ms and the ratios of the fuel mass in the first injection to the fuel mass in the second injection were 4/1 and 5/1 respectively under the test conditions. Additionally, the dual-injection strategy with an optimized control parameter produced a higher heat release and higher indicated work than the single-injection strategy did.

Effects of throat area and inlet area of intake port on mixture formation of gasoline direct injection engines

2018 ◽  
Vol 233 (5) ◽  
pp. 1150-1161
Author(s):  
Zhaolei Zheng ◽  
Hanyu Liu ◽  
Xuefeng Tian
Keyword(s):  
High Speed ◽  
Ignition Time ◽  
Direct Injection ◽  
Fuel Mixture ◽  
Flow Coefficient ◽  
Gasoline Direct Injection ◽  
Intake Port ◽  
Mixture Formation ◽  
Direct Injection Engine ◽  
Gasoline Direct Injection Engine

To study the effects of intake port structure parameters (inlet area and throat area) of a gasoline direct injection engine on mixture formation, a steady-flow test and transient simulation with four kinds of intake ports (named Cases 1–4) were simulated using AVL FIRE; a four-valve, four-cylinder gasoline direct injection engine with Case 1 was also operated under wide-open-throat conditions with a speed of 5500 r/min as the test basis. According to the simulation results, the flow coefficient increased with an increase in throat and decrease in inlet areas; however, a reverse change of them can improve the tumble ratio. In addition, the tumble ratio in a cylinder can be increased by reducing the throat and inlet areas. However, the concentration is not notable at high-speed wide-open-throat conditions. A larger tumble ratio and stronger turbulent kinetic energy intensity of in-cylinder flow are beneficial to form a homogeneous mixture, which ensures a better distribution of air–fuel mixture at ignition time. Moreover, larger inlet area and smaller throat area ensure less NO emissions.

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