Experimental and Large Eddy Simulation Study for Visualizing Complex Flow Phenomena of Gas Turbine Internal Blade Cooling Channel with No Bend

In this study, the internal cooling channel was investigated without any bend. Smooth surfaces and dimpled surfaces were investigated using the different combinations of connecting circular and rectangular holes. The computations were performed using the Large Eddy Simulation (LES) model for Reynolds (Re) numbers from 10,000 to 50,000. A total of six different connecting holes were investigated with a smooth and dimpled surface. A partial spherical dimple with two circular holes showed the highest heat transfer, but it has a higher pressure loss penalty. Even though the Leaf dimple with the rectangle indicated a low heat transfer because of low-pressure drops, it represents the highest efficiency at higher Reynolds numbers.

Machine vision-based relative-angle measurement system between circular holes

In this study, the machine-vision technique is employed to measure the angle between two circular holes for the derailleur parts of a bicycle. A delta robot equipped with a motorized zoom lens is constructed as an automatic measurement device. In this way, we can detect the normal vectors of circular holes with different positions and sizes by using only one camera. By calculating the plane normal vectors of two circular holes within the camera coordinate system and performing the cross-product operation, the angle between the two circular holes is obtained. Simulation experiments reveal that the measurement method is influenced by the projection eccentricity error, and the error can be reduced by increasing the focal length and employing the virtual-center alignment method. The results show that the average error for measuring the derailleur parts is approximately 0.061°, and the standard deviation is 0.112°. Experimental analysis indicates that while the magnification of the image is larger, the average error of the measurement result is reduced, and the standard deviation is reduced as well. When the magnification is 0.4×, the measurement average error is 0.04°, and standard deviation is 0.101°. When the distance between the center of the circle and the center of the image is increased, the error in the angle calculation is also increased. A significant improvement is obtained by setting the fitting center position to the optical central position, which omits the influence of the error amplification caused by the distance of the circular hole from the optical axis.

Prediction of the Unsteady Turbulent Flow in a Solar Air Heater Test Bench

In this work, the unsteady turbulent flow in a new solar air heater test bench, developed in our LASEM laboratory, was predicted. The considered system consists of two passages solar air heater separated by an absorber and powered by a fan working in a delivery mode, placed in the hole inlet side the insulation. On this system, a glass is hanging on the front side and an absorber is inserted inside. On the glass side, it is connected to the box prototype through a pipe. The hot air flow is routed towards the box prototype. Two circular holes, are located in the same face of the box prototype. The inlet hole allows the hot air supply. However, the outlet hole allows its escape into the ambient environment. By using the ANSYS Fluent 17.0 software, the Navier-Stokes equations coupled with the standard k-ω turbulence model were resolved. The numerical results were compared with our experimental data, established in the second passage of the solar air heater test bench. The good agreement confirms the validity of the numerical method. The range of temperatures is very useful in many applications such as industrial and domestic applications.