An experimental study of heated jets in a cross-flow from stacks of various geometries

Jets;Jets in Cross-Flow;particle image velocimetry (PIV);Proper Orthogonal Decomposition (POD);Turbulence

Johnson, Blake

关键词: Jets;    Jets in Cross-Flow;    particle image velocimetry (PIV);    Proper Orthogonal Decomposition (POD);    Turbulence;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/31119/Johnson_Blake.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Heated jets in cross-flow (JICFs) occur in a wide variety of situations in engineering practice and the natural environment.Because many industrial and environmental JICFs involve raised-stack emission, non-circular mouths under the influence of shifting winds, and oftentimes strongly heated jet fluid, there is a need for further investigation into the effects that such influences have upon the jet development.Two-dimensional particle image velocimetry (PIV) measurements are performed in the plane of symmetry aligned with the cross-flow of the near-field of the jet while stereoscopic PIV (sPIV) measurements are made in the spanwise--wall-normal plane at three far-field cross-sections downstream of a raised jet stack.Temperature measurements are also made in the same planes as the sPIV measurements. The raised jetis set at such a height that it emits into a uniform free-stream environment free of the boundary-layer effects that impact jets that exit flush with the boundary. Heated jets are studied that emit at centerline temperatures T0 significantly higher than ambient temperature T1, achieving temperature ratios T0/T1 of1.4 and 2.Measurements are also made of two unheated JICFs at approximately the same Reynolds numbersRe0 = V0D/v0 and Re1=U1D/v1, respectively, of the heated jet, all at blowing ratio r0 = 4.5. The flow from rectangular stacks of varying aspect ratio and orientation relative to the cross-flow is compared to that of a circular JICF.Interacting JICFs from arrays of rectangular stacks are also investigated.Properorthogonal decomposition is applied to the PIV data to explore structural differences and any redistribution of Reynolds stress arising in the heated JICF vs. that of the unheated cases.