Measurement of boundary layer structures in chocolate cooling process

2020 ◽  
Vol 2020 (0) ◽  
pp. OS05-12
Author(s):  
Kento YAMADA ◽  
Hyun Jin PARK ◽  
Yuji TASAKA ◽  
Yuichi MURAI
2014 ◽  
Vol 142 (5) ◽  
pp. 1874-1891 ◽  
Author(s):  
Karen A. Kosiba ◽  
Joshua Wurman

Abstract Two Doppler on Wheels (DOW) mobile radars collected fine-spatial-scale dual-Doppler data in the right-front quadrant and eye of Hurricane Frances (2004) as it made landfall near Stuart, Florida. A 5.7-km dual-Doppler baseline established a dual-Doppler domain south and east of Fort Pierce, Florida, encompassing a 5.5 km × 5.5 km horizontal area, with a grid spacing of 20 m, allowing for the resolution of subkilometer-scale horizontal structures and associated kinematics. Three-dimensional vector wind analyses of the boundary layer revealed the presence of linear coherent structures with a characteristic wavelength of 400–500 m near the surface that increased in size and became more cellular in shape with increasing height. Average horizontal perturbation winds were proportional to average total horizontal winds. Within the eye of the hurricane, the features lost linear coherency despite a high mean wind speed, possibly due to changes in stability. A slight decrease in the characteristic wavelength of boundary layer structures was documented as the winds cross the barrier islands east of Fort Pierce. Vertical flux of horizontal momentum caused by individual vortical structures was substantially higher than values employed in turbulence parameterization schemes, but the domain-wide average flux was substantially lower than that in individual structures, likely due to the transient nature of the most intense portions of the structures. Analysis of the turbulent kinetic energy (TKE) yielded values comparable to those reported in previous observational studies over the open ocean. However, there was substantial variability in TKE within the dual-Doppler domain, emphasizing the challenge in obtaining representative samples using non-3D measurements such as dropsondes.


2019 ◽  
Vol 32 (2) ◽  
pp. 1905117 ◽  
Author(s):  
Wenming Li ◽  
Zuankai Wang ◽  
Fanghao Yang ◽  
Tamanna Alam ◽  
Mengnan Jiang ◽  
...  

2018 ◽  
Vol 53 ◽  
pp. 03010
Author(s):  
Changyi Xu ◽  
Yan Wang

Based on Doppler radar 3D-composited reflectivity, wind profiler radar, boundary layer Tianjin tower of 255m as well as intensified automatic surface observation data, the evolution of the boundary layer associated with two successive gust front processes in the evening of 10 June 2016 and the intensity of the related disastrous surface high wind were analyzed. The results shown as follows: (1) To the same storm cell, the wind intensity caused by the outflow boundary in the main body was stronger than the wind caused by the gust front. The intensity of the disastrous high wind was related to the maximum descending velocity in the boundary layer and the associated height. The stronger the maximum descending velocity and the lower the level, the stronger the disastrous high wind was. (2) The tower data indicated, as the approaching of the gust front, convergence fluctuations first emerged at low(20m) and middle(120m) levels of the tower, leading the emergence of disastrous high wind by 8 minutes. When the gust front passed over, the maximum variations of cooling and the wind velocity were in pace with each other.


1986 ◽  
Vol 108 (1) ◽  
pp. 116-123 ◽  
Author(s):  
K. Rued ◽  
S. Wittig

The accurate prediction of heat transfer coefficients on cooled gas turbine blades requires consideration of various influence parameters. The present study continues previous work with special efforts to determine the separate effects of each of several parameters important in turbine flow. Heat transfer and boundary layer measurements were performed along a cooled flat plate with various freestream turbulence levels (Tu = 1.6−11 percent), pressure gradients (k = 0−6 × 10−6), and cooling intensities (Tw/T∞ = 1.0−0.53). Whereas the majority of previously available results were obtained from adiabatic or only slightly heated surfaces, the present study is directed mainly toward application on highly cooled surfaces as found in gas turbine engines.


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