Optimization Design Of Inner-structure Of The Slot-jet In Aircraft Cabin And Investigation Of Multi-scale Characteristic In Slot Turbulent Jet Flow

Hot-Wire Anemometry and Time-Resolved Particle Image Velocimetry are accepted to the experiments in MD-82 cabin and the simplified cabin model respectively,which is based on to carry out the research on the optimization design of inner structures of the slot-jet in aircraft cabin and multi-scale characteristic analysis of the turbulence.The slot-jet flow field in model cabin environment with different inner-structure are finely measured by constant-temperature anemometry system with the resolution higher than the smallest time-scale of turbulence(inner structure and Dissipation time-scale).Analyzing the actual velocity field in stream-wise direction and normal direction respectively.Furthermore,Basing on the comfort theory,Wavelet-transform are applied for the characteristic analysis of the multi-scales eddy and analyzing the distribution of energic scale Dissipation-scale and Taylor Differential-scale in perspective of producing and dissipation of the turbulence energy.The variation of mean velocity beyond the slot outlets reveals the decaying regularity of the velocity in stream-wise direction and the flow irregularity in normal direction. Results from the Wavelet-transform analysis indicate the energy proportion of different scale eddies is connected with the evolution of the slot-jet flow field.We can see from the results that small scale vortexes generate entrainment and merge into large scale vortexes on account of the increase of the viscosity and the decrease of the inertness in the far field of the turbulence jet flow field,which is called inverse energy cascade will have a significant impact on the thermal transmission and the diffusion of contaminant and is the main reason cause draft sensation discomfort.In order to the problem that the distribution of the mean stream-wise velocity field of the slot outlet is nonuniform,we designed the slit-shaped inner core structure.By the contrast experiments,Slit-shaped core inner structure is designed so that the outlet slot-type flow more evenly mixed and more fully developed turbulence.From the perspective of flow fluctuation frequency on comfort analysis,the installation of a slit-shaped crack in the core structure of the air flow field flow characteristic frequency has remained at about 21.83 Hz,when the air fluctuation frequency which will result in the most uncomfortable is 0.2Hz ~ 0.6Hz.So we can say the design is worked.The flow fields around the air-supply grill on the wall of the MD-82 cabin were experimentally measured by TRPIV,which conform that the experiment in the simplified cabin mode is effective.