Session: 07-01: Thermal-Hydraulics Experimental Studies - I

Paper Number: 64534

Start Time: August 4, 2021, 01:15 PM

64534 - Experimental Study of Flow Characteristics in Round Jet Flow Using Particle Image Velocimetry (PIV) 

Jetting phenomenon could be found in many places in nuclear reactor engineering. A free jet could be considered as a simplification of a jet. The study on the instaneous velocity field is beneficial for the modelling of turbulent flow, which is also meaningful for the design of safety-related system and the analysis of the consequences of accidents relevant to jet phenomenon. In this paper, high-resolution particle image velocimetry (PIV) was used to study the flow characteristics in the nearfield of a turbulent round water jet issuing from a circular nozzle. Mean velocity, velocity gradient, turbulence intensity, Reynolds stress, viscous stress, vorticity and other turbulence statistics are investigated over a range of jet Reynolds number Re (based on jet exit velocity and equivalent nozzle diameter) varying from 50 to 10000. The distribution of parameters of different Reynolds numbers and different height sections was studied. The velocity measurements reveal that all exit jet profiles in the near-field closely approximate a single peak shape, and they show strict self-similarity. Compare turbulence intensity, Reynolds stress, viscous stress with different Reynolds number jet, the self-similarity is shown along jet path when Reynolds number is low, and the self-similarity is shown after the turbulence is fully developed when Reynolds number is high. The shapes of Reynolds stress of high Reynolds number jet change from double peak to single peak along jet path, and the shapes are always single peak at low Reynolds numbers. This critical Reynolds number is about 2000. In addition, the turbulence statistics can be used to correct the coefficients of the turbulence equation and Large eddy simulation.

Presenting Author: Lei Wu Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment, Harbin Engineering University

Authors:

Lei Wu Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment, Harbin Engineering University
Jianjun Wang Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment, Harbin Engineering University