多射流喷射器的压电激励特性

采用数值模拟方法研究了多射流喷射器的压电激励特性，获得了喷射器的压力、流量和速度波动特性。研究结果表明:多射流喷射器内的压力脉动主要受壁面运动特性影响，压力振幅随激励频率增大而增大；而封闭腔内的压力脉动与壁面位移造成的容积变化有关，压力振幅不随激励频率变化，因此基于封闭腔假设的理论计算方法不能准确预测喷射器的压力脉动。在多射流喷射器内，入口和出口的流量振幅不相同；不同位置的压力振幅分布不均匀导致了不同喷孔的速度振幅存在差异，并对射流形态产生影响。 

Piezoelectric excitation property of multi-nozzle injector

The piezoelectric excitation property of multi-nozzle injector was studied by numerical simulation. Pressure, mass flow rate and fluctuation of velocity of the injector were obtained. The results showed that the pressure fluctuation was mainly influenced by wall motion characteristics, and the pressure amplitude increased with the increasing excitation frequency in multi-nozzle injector. But in the obturated cavity, the pressure fluctuation mainly depended on change of the cavity cubage, and the pressure amplitude didn''t vary with the excitation frequency. Thus theoretical method of obturated cavity could not nicely forecast the pressure fluctuation in injector. In the multi-nozzle injector, the mass flow rate amplitude at inlet and outlet was different. The pressure amplitude distributed non-uniformly in different positions, resulting in different velocity amplitudes at multi-nozzle outlet, and also different jet shapes.