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The forward variable area bypass injector (FVABI) is a key component of double bypass variable cycle engine (VCE) to achieve mode transition and bypass ratio adjustment. In this paper, an experimental system for FVABI was constructed based on the analysis of relevant experimental theories, and then the experiments on FVABI were carried out for a specific working state in double bypass mode of VCE and for the comparison working states with different area ratios and different back pressure ratios. The results showed that the FVABI designed in this paper meets the requirements of VCE at this working state. The analysis of the influence of area ratio and back pressure ratio on the injection coefficient showed that the first bypass valve and back pressure were effective means to control the mass flow of FVABI.

The synthetic jet actuator was applied to the nozzle jet vector control by experimental and numerical simulation methods to study fluid thrust vector control in this paper. The nozzle jet produced a steady and continuous deflection under the action of synthetic jet actuators. Through the analysis of the flow structure and control mechanism of the interaction between the synthetic jet and the nozzle jet, it was found that the force formed by the pressure gradient in the nozzle duct, the entrainment and ejection of the synthetic jet to the mainstream, and the momentum synthesis of the vertical synthetic jet were able to cause the deflection of the nozzle jet. The actuator excitation voltage can adjust synthetic jet velocity, which in turn affects the nozzle jet deflection angle.

Synthetic jets perpendicular to the mainstream have been used to experimentally study the coaxial jets mixing enhancement in this paper. The parameters of coaxial jets such as vorticity, streamwise velocity, radial velocity, Reynolds shear stress, and turbulence intensity are measured using the particle image velocimetry (PIV) and hot wire anemometers. The distribution characteristics of these parameters with and without synthetic jets were obtained. The mechanism of coaxial jets mixing enhancement using synthetic jets was summarized by analyzing these experimental results, and it was also found that the momentum coefficient was the most critical factor for jets mixing enhancement. The comparative experiments fully verified the mechanism, showing that with an appropriate momentum coefficient, the synthetic jets significantly enhanced coaxial jets mixing.

For a certain type of turbofan engine, the mathematical model of the intake air humidity is established in this paper. Then the influence of intake air humidity on the cross-section parameters of the turbofan engine and the characteristics of the compressor are analyzed. In addition, we considering the influence of water vapor on combustion efficiency. The results show that: in a certain range of intake air humidity, with the increase of intake air humidity, the effect on the compressor pressure ratio is small, but the flow will have decreased. In the combustion process, it will increase fuel consumption and energy consumption. Finally, it causes the total thrust of the turbofan engine to fall and the fuel consumption rate increases.