Application of high-speed thermographic visualization for validation of numerical simulations of liquid boundary layer flows

2018 ◽  
Vol 10 (2) ◽  
pp. 112-121
Author(s):  
E.Yu. Koroteeva
Keyword(s):  
Boundary Layer ◽  
Numerical Simulations ◽  
High Speed ◽  
Boundary Layer Flows ◽  
Liquid Boundary ◽  
Thermographic Visualization ◽  
Liquid Boundary Layer

Raman Spectrum Analysis on the Solid–Liquid Boundary Layer of BGO Crystal Growth

2007 ◽  
Vol 24 (7) ◽  
pp. 1898-1900 ◽  
Author(s):  
Zhang Xia ◽  
Yin Shao-Tang ◽  
Wan Song-Ming ◽  
You Jing-Lin ◽  
Chen Hui ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Raman Spectrum ◽  
Crystal Growth ◽  
Spectrum Analysis ◽  
Liquid Boundary ◽  
Solid Liquid ◽  
Liquid Boundary Layer

An Experimental Investigation on the Characteristics of Turbulent Boundary Layer Flows Over a Dimpled Surface

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Wenwu Zhou ◽  
Yu Rao ◽  
Hui Hu
Keyword(s):  
Boundary Layer ◽  
Experimental Investigation ◽  
Turbulent Boundary Layer ◽  
Flat Plate ◽  
Surface Pressure ◽  
High Speed ◽  
Boundary Layer Flows ◽  
Piv Measurement ◽  
Measurement Results ◽  
Flow Features

An experimental investigation was conducted to quantify the characteristics of the turbulent boundary layer flows over a dimpled surface in comparison to those over a conventional flat plate. In addition to measuring surface pressure distributions to determine the friction factors of the test plates and to map the surface pressure inside the dimple cavity, a high-resolution digital particle image velocimetry (PIV) system was used to achieve detailed flow field measurements to quantify the characteristics of the turbulent boundary layer flows over the test plates and the evolution of the unsteady vortex structures inside the dimple cavity at the middle of the dimpled test plate. It was found that the friction factor of the dimpled plate would be about 30–80% higher than that of the flat plate, depending on the Reynolds number of the test cases. In comparison with those over a conventional flat surface, the flow characteristics of the turbulent boundary layer flows over the dimpled surface were found to be much more complicated with much stronger near-wall Reynolds stress and higher turbulence kinetic energy (TKE) levels, especially in the region near the back rims of the dimples. Many interesting flow features over the dimple surface, such as the separation of oncoming boundary layer flow from the dimpled surface when passing over the dimple front rim, the formation and periodic shedding of unsteady Kelvin–Helmholtz vortices in the shear layer over the dimple, the impingement of the high-speed incoming flow onto the back rim of the dimple, and the subsequent generation of strong upwash flow in the boundary flow to promote the turbulent mixing over the dimpled surface, were revealed clearly and quantitatively from the PIV measurement results. The quantitative measurement results are believed to be the first of its nature, which depict a vivid picture about the unique flow features over dimpled surfaces and their correlations with the enhanced heat transfer performance reported in previous studies.

Study of Incident Drag Response of Hyperloop Pod Based on Change in Aerodynamic Brake Plate Orientation

2021 ◽  
Author(s):  
Shadman Mahmud ◽  
Adib Adnan ◽  
Shahnoor Shamim Khan ◽  
Md. Hamidur Rahman
Keyword(s):  
Boundary Layer ◽  
Numerical Simulations ◽  
High Speed ◽  
Boundary Layer Separation ◽  
Pressure Gradients ◽  
Transport Models ◽  
Layer Separation ◽  
Passenger Safety ◽  
Speed Flow ◽  
Aerodynamic Brake

The idea for the Hyperloop has received significant attention, with expectations of it becoming a revolutionary and potentially the fastest mode of land transportation on the planet. The low-pressure tube through which the pod travels at expected speeds close to Mach 1.0, presents a unique case among other transport models, and as such, braking of the pod is of critical importance if passenger safety protocols are to be maintained. The high-speed flow around the pod exerts high adverse pressure gradients on the pod surface, resulting in boundary layer separation, increasing drag and affecting the acceleration of the pod. Numerical simulations have shown that the placement of an aerodynamic brake plate on the pod surface at the point at which boundary layer separation occurs provides the necessary drag required for safe deceleration. This study was aimed to find the best angle for the aerodynamic brake positioned at a fixed point on the pod, allowing for the maximum generation of drag, using numerical simulations. After various trials, it was observed that angling the brake 15° backwards while increasing its length to keep incident brake profile constant, the drag value obtained was the highest.

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