Jianqin Fu

Study of Energy-Saving Potential of Electronically Controlled Turbocharger for Internal Combustion Engine Exhaust Gas Energy Recovery

To promote the energy utilization efficiency of internal combustion engine, the approach of electronically controlled turbocharger (ECT) for IC engine exhaust gas energy recovery was investigated by the method of test coupling with numerical simulation. First, the tests for turbocharged gasoline engine and high-speed motor were conducted so as to provide experimental data for numerical simulation. Then, the simulation model of ECT engine was built and calibrated, and the working processes of ECT engine were simulated. The results show that the recovered exhaust gas energy by ECT increases with the decrease of by-pass valve opening due to the rising of exhaust gas mass flow rate, but the pumping loss also ascends; limited by the original engine turbocharger map, the engine working points are beyond turbine map when the by-pass valve opening increases to a certain degree. To further improve the energy recovery potential of ECT, a larger turbine was rematched, and the working processes of ECT engine under the whole operating conditions were resimulated. The results indicate that engine exhaust gas energy cannot be recovered by ECT in low-load and low-speed area due to the low exhaust gas pressure. In the effective working area, as the load and speed ascend, both the recovery efficiency of ECT and the utilization efficiency of exhaust gas energy increase, and their maximum values reach 8.4% and 18.4%, respectively. All those demonstrate that ECT can effectively recover engine exhaust gas energy.

A research of turbocharged gasoline transient response

To improve transient response of turbocharged gasoline, various kinds of optimization methods were studied by using engine performance simulation software GT-POWER. The results showed that: increasing valve overlap, using the series composite supercharge and replacing the original turbocharger with a VNT turbocharger can improve transient response characteristics of the original supercharge engine, when using the series composite supercharge, transient response of turbocharged gasoline hardly has any “hysteresis” phenomenon.

A hybrid method of tests coupled with simulations used to detect the working processes of an automotive engine from cycle to cycle in transient conditions

To improve the actual performance of an automotive engine, an approach consisting of dynamic signal measurements coupled with gas dynamics–thermodynamics process simulations is proposed; this is used to detect the working processes of an automotive engine from cycle to cycle in transient conditions. Based on the working principles and the mathematical models of the proposed detection method, corresponding software was developed, and the reliability of this approach was validated on an automotive engine. Automotive road tests were conducted, and various transient parameters of the engine were successfully detected from cycle to cycle by using the developed software. On this basis, the variations in the influencing factors of and the interactions between various engine parameters were analysed. The results showed that the ignition timing has a strong effect on the indicated thermal efficiency. Where there is an unnecessary delay in the ignition timing, there is a decrease in the indicated thermal efficiency. The pumping mean effective pressure is approximately equal to the difference between the exhaust gas pressure and the intake gas pressure for a low to medium load, but it is much higher than the pressure difference and undergoes great fluctuations in the high-speed and high-load operating regions. Both the presented approach and the research results are significant for improving the engine performance in transient conditions.

A method to reduce engine intake noise based on numerical simulation

In order to reduce intake noise without affecting the intake performance of motorcycle engine, computer simulation was used to optimize the design of intake system. Firstly, the GT-power simulation model of original engine was built and calibrated based on engine test data. Next, the performances of original engine, such as volumetric efficiency and intake noise, were obtained by simulation calculation. Then, based on Helmholtz resonance principle, the intake system was optimized aimed at the noise peak frequencies. The intake noise and intake performance of optimized intake system were obtained through re-simulation. Compared to the results of original engine, the optimized intake system can greatly reduce intake noise almost without decreasing intake volumetric efficiency. The study results have provided a good method for optimizing intake system.

A method on pre-matching of engine with turbocharger and their applications

Based on the engine performance requirements and flow characteristics of supercharger, the paper presents a method on pre-matching of engine with turbocharger. Combined with database, the special software for matching of turbocharger is developed. To match of a natural inspiration gasoline engine with turbocharger, the turbocharger is chosen via this method firstly, and then the turbocharged gasoline GT-power model is built. After comparing the results of simulation with experiment, it can be conclude that the pre-matching results are consistent with the simulation results, and can reflect the actual situation in experiment, especially at mid-speed and low-speed. At the same time, the turbocharger works stably and reliably, and the engine achieves its torque target. The method provides the theoretical basis for matching of engine with turbocharger, and has certain practical significance and applicative value of project.