Active control of the charge motion by fluidic vortex generators

现代内燃机利用设计的气缸充气运动来支持混合气的形成和/或燃烧。为了产生装药运动，使用了形状适当的进气口。一般来说，电荷运动的增加会导致流动能力降低，从而增加电荷交换功。在这个项目中，我们将研究一种替代的涡流产生方法。作为基础，使用了一个几乎不会产生电荷运动的端口。通过将空气切向脉冲喷射到靠近阀门阀座的端口中，可以增加这一点。这使得可以连续改变涡流，这与通常打开和关闭端口不同。此外，初步工作表明，产生压缩空气所需的功小于使用旋流口将导致的电荷交换功的增加。该项目将在布伦斯韦格理工大学流体力学研究所(ISM)和内燃机研究所(IVB)进行。在前期工作的基础上，最初将设计一系列港口。这些将由ISM通过静态RAN模拟进行研究。结果是旋流与流量之间的帕累托前锋。从这个帕累托前端，将选择三个不同旋涡级别的端口。为了验证模拟结果，将在IVB流动试验台上进行实验研究。将使用低旋流和中旋流的流道进行进一步的空气喷射测试。对于非定常研究，将建立一个带有机动发动机的试验台。气缸盖的设计将使进气口可以很容易地交换。流量测量将使用热线风速计进行，因为使用这种技术可以比光学方法更快地得出结果。这一点很重要，因为由于空气注入的变化，参数空间很大。ISM将为非定常调查建立一个uRANS和IDDES模拟链。仿真软件采用OpenFOAM。利用这些工具，将进行系统的优化。目标是一个参数星座，该星座提供较高的涡流增量和较低的做功以产生压缩空气。然后，可以使用不需要空气注入而产生低涡流的端口，从而具有高流量。最后，对发动机进行了模拟评估。通过联合调整的方法，包括实验参数研究和详细的重新计算与尺度分辨模拟，可以解释和描述空气注入对涡旋发展的影响和相关的敏感性。

Modern internal combustion engines utilize a designed motion of the cylinder charge to support mixture formation and/or combustion. For the generation of charge motion appropriately shaped intake ports are used. Generally an increase in charge motion causes a reduced flow capacity and thus an increased charge exchange work. In this project an alternative method of swirl generation will be investigated. As a basis a port is used which creates little charge motion. This will be increased by tangential pulsed injection of air into the port close to the valve seat. This makes it possible to vary the swirl continuously, different from switching ports on and off as usual. Further the preliminary work shows that the work needed to produce the compressed air is less than the increase of charge exchange work that would result from using a swirl port. The project will be carried out at the Institute of Fluid Mechanics (ISM) and the Institute of Internal Combustion Engines (ivb) at TU Braunschweig. Initially a series of ports will be designed, based on the preliminary work. These will be investigated by ISM with stationary RANS-simulations. The result is a pareto front of swirl vs. flow capacity. From this pareto front three ports with different swirl level will be chosen. They will be investigated experimentally on the flow test bench of ivb, in order to verify the simulation results. Further tests with air injection will be carried out using the ports with low and medium swirl. For unsteady investigations a test bed with a motored engine will be built up. The cylinder head will be designed such, that the inlet ports can be exchanged easily. The flow measurements will be carried out with hot wire anemometers, because with this technique the results are available much faster than with optical methods. This is important because of the large parameter space due to the variabilities of the air injection. The ISM will build up a simulation chain of uRANS- and IDDES-simulations for the unsteady investigations. OpenFOAM will be used as the simulation software. Using these tools a systematic optimisation will be carried out. The target is a parameter constellation, which gives a preferably high increase in swirl with a preferably low work for the production of compressed air. Then a port can be used which produces low swirl without air injection and has thus a high flow capacity. Finally engine simulations will be carried out for evalution. With a jointly adjusted approach involving experimental parameter studies and detailed recalculations with scale resolving simulations the effect of air injection on the development of swirl and the connected sensitivities can be explained and described.