Jianwei Mo

Design of an Asymmetric Scramjet Nozzle with Circular to Rectangular Shape Transition

A novel method for optimizing the shape of a three-dimensional scramjet nozzle with circular to rectangular shape transition, which aims to improve airframe integration, is presented in this paper. To generate the shape of the nozzle, the streamline tracing technique is used based on an annular optimum thrust nozzle flowfield calculated using the method of characteristics. The research is conducted using both the computational fluid dynamics approach and wind-tunnel experiments. Viscous flowfields are computed under the design conditions using commercial software Fluent in order to access the aerodynamic performance of the nozzle. The obtained computational fluid dynamics results on flow static pressures on the upper and lower walls of the three-dimensional nozzle have been validated against the measurement data. Comparisons of the computational fluid dynamics and wind-tunnel experimental results have been conducted under two specific nozzle pressure ratios; that is, underexpansion condition with nozzle p...

New adaptive sampling method in particle image velocimetry

This study proposes a new adaptive method to enable the number of interrogation windows and their positions in a particle image velocimetry (PIV) image interrogation algorithm to become self-adapted according to the seeding density. The proposed method can relax the constraint of uniform sampling rate and uniform window size commonly adopted in the traditional PIV algorithm. In addition, the positions of the sampling points are redistributed on the basis of the spring force generated by the sampling points. The advantages include control of the number of interrogation windows according to the local seeding density and smoother distribution of sampling points. The reliability of the adaptive sampling method is illustrated by processing synthetic and experimental images. The synthetic example attests to the advantages of the sampling method. Compared with that of the uniform interrogation technique in the experimental application, the spatial resolution is locally enhanced when using the proposed sampling method.