Experimental Study Of The Airflow Characteristics In A Passenger Aircraft Cabin Mockup With 2D-PIV

Air distributions play the most critical and fundamental role in controlling the aircraft cabin environment quality.To evaluate and improve the performance of cabin air distributions,the first step is to quantify how the complex and unsteady airflows get distributed within the cabin.Therefore,the objective of this research is to find a suitable measuring method to reveal the characteristics of the low Reynolds number turbulence in cabin,which lay a foundation for further designing a healthy,thermally comfortable and energy-efficient environmental control system(ECS).In this research,a robust and high power 2D-PIV system was applied to investigate the mutil-scale airflow characteristics inside a single-aisle and partially-transparent aircraft cabin mockup,under different boundary conditions.The innovation points of this research can be concluded as:(1)A large-scale 2D-PIV splicing measurement system was established based on the aircraft cabin mockup experimental platform.On this basis,a comprehensive PIV splicing measuring method was proposed focusing on the aircraft cabin airflows.Comparing with other methods,the PIV splicing method achieve an appropriate balance between the large area coverage and high spatial resolution(11mm),which is helpful to gain a greater insight into the cabin flow features.(2)By using the large-scale PIV splicing measurement method,a high spatial resolution and full-scale flow field database was acquired in different sections in the cabin mockup,under both the isothermal and cooling conditions.Then the whole-field airflow characteristics and their key influencing factors were analyzed in the whole cabin dimension.Finally,the reliability and reproducibility of the PIV data were verified by the self-validation.(3)Both the time-averaged and non-linearly transient jet flow features were revealed by the PIV measurements,from the lateral slot diffusers,under the isothermal and non-isothermal conditions.The flow confinement effects on the jet development were analyzed.The key influencing factors were extracted from the complex jet flow,using the similarity law of the criterion numbers.The criterion numbers were also used to quantitatively study the interactions between the inertial force and the buoyancy on the jets.Then mathematical models were established to describe the relationships between the fluid boundary conditions and jet flow characteristics,which provided a design reference for the airflow regulations in micro-environment around the passengers.The research mainly led to following conclusions:(1)The global airflow fields were govern by the inertial force.Meanwhile,the thermal buoyancy also played an important role in the jet growth by pulling down the jet trajectories and spreading the jet profiles larger.The buoyancy also help the jet induce more ambient air by mixing mechanism in both the boundary and free shear regions,which contributed to a greater removal efficiency of the contaminant and convective heat generated by the passengers.Therefore,the micro-environment quality around the passengers were mainly influenced by the jet flow;(2)The cabin lateral jets went through a transition from free jets into wall jets by the Coanda effect.Thus,the jet development needs to be divided into several regions.The jet characteristics were obviously influenced by the flow confinement,which could not achieve a fully-developed state.The flow criterion numbers directly determined the jet characteristics and the flow pattern.For instance,the non-isothermal jets could achieve a fully-rotatory flow pattern only when Re?4170 and Arc?4.5.