The effects of a late intake valve phase (LIVP) strategy on crank-angle resolved real-time turbocharger efficiency were analyzed. The research is composed of experiments and simulations. In the experiments, an engine test was conducted with a downsized 2.0 L 4-cylinder turbocharged-gasoline direct injection (T-GDI) engine. In order to evaluate the effects of LIVP on the instantaneous turbocharger efficiency, the intake valve phase was retarded from its reference phase to 30 crank angle degrees (CADs) by steps of 10 CADs, while maintaining the fixed position of the other engine control parameters. Pressure in the intake and exhaust systems and turbocharger rotational speed were also measured in the experiments. In the simulation, a 1-D simulation model was built to simulate the same conditions as in the experiments. Instantaneous turbine mass flow rate as well as, temperature upstream and downstream of the turbine were extracted from the model in the units of CAD. This was done because it is inherently impossible to measure these data in the units of CAD with the existing real-world mass flow meter and thermocouples. The instantaneous blade speed ratio (BSR), turbine efficiency, and mass flow parameter were calculated by combining the results of the experiment and the 1-D simulation. In the results, the instantaneous turbine efficiency was divided into two phases and analyzed. First, in the filling phase, the effects of exhaust blow-down pulse arrival on the instantaneous turbine efficiency were analyzed. Second, in the emptying phase, the effects of exhaust gas scavenged from the cylinder on the instantaneous turbine efficiency were analyzed. The instantaneous turbine efficiency showed strong unsteady characteristics and deviated from the quasi-steady performance line. This was due to large fluctuations in the turbine inlet conditions. With the application of the LIVP strategy, the instantaneous turbine efficiency was increased. This was because of a decrease in the amount the waste-gate opened while meeting the same engine load lead to more exhaust gas energy entering the turbine, and the turbine’s operating conditions were changed to more efficient conditions. Finally, correlation of the engine thermal efficiency rising according to the instantaneous turbine efficiency rising was confirmed.

分析了后期进气门相位（LIVP）策略对曲轴角解析实时涡轮增压器效率的影响。该研究由实验和模拟组成。在实验中，发动机测试是使用小型2.0升4缸涡轮增压汽油直喷（T-GDI）发动机进行的。为了评估LIVP对瞬时涡轮增压器效率的影响，进气门相位从其参考相位以10 CAD的步长从其参考相位延迟到30曲轴角度（CAD），同时保持其他发动机控制参数的固定位置。在实验中还测量了进气和排气系统中的压力以及涡轮增压器的转速。在模拟中，建立了一维模拟模型来模拟与实验中相同的条件。涡轮瞬时质量流量以及涡轮上游和下游的温度以CAD为单位从模型中提取。这样做是因为使用固有的现实世界质量流量计和热电偶，以CAD为单位固有地无法测量这些数据。结合实验结果和一维模拟结果，计算了瞬时叶片速比（BSR），涡轮效率和质量流量参数。结果将瞬时涡轮效率分为两个阶段并进行了分析。首先，在填充阶段，分析了排气排污脉冲的到达对瞬时涡轮效率的影响。其次，在排空阶段，分析了从汽缸排出的废气对瞬时涡轮效率的影响。瞬时涡轮效率显示出很强的不稳定特性，并且偏离了准稳定性能线。这是由于涡轮机进气口条件的大幅波动所致。随着LIVP策略的应用，瞬时涡轮效率得以提高。这是因为在满足相同发动机负载的同时打开的废气门数量减少，导致更多的废气能量进入涡轮，并且涡轮的运行条件已更改为更有效的条件。最后，确认了根据涡轮瞬时效率的上升而使发动机热效率上升的相关性。随着LIVP策略的应用，瞬时涡轮效率得以提高。这是因为在满足相同发动机负载的同时打开的废气门数量减少，导致更多的废气能量进入涡轮，并且涡轮的运行条件被更改为更有效的条件。最后，确认了根据涡轮瞬时效率的上升而使发动机热效率上升的相关性。随着LIVP策略的应用，瞬时涡轮效率得以提高。这是因为在满足相同发动机负载的同时打开的废气门数量减少，导致更多的废气能量进入涡轮，并且涡轮的运行条件已更改为更有效的条件。最后，确认了根据涡轮瞬时效率的上升而使发动机热效率上升的相关性。