Transverse jet-cavity interactions with the influence of an impinging shock

For high-speed air breathing engines, fuel injection and subsequent mixing with air is paramount for combustion. The high freestream velocity poses a great challenge to efficient mixing both in macroscale and microscale. Utilising cavities downstream of fuel injection locations, as a means to hold the flow and stabilise the combustion, is one mechanism which has attracted much attention, requiring further research to study the unsteady flow features and interactions occurring within the cavity. In this study we combine the transverse jet injection upstream of a cavity with an impinging shock to see how this interaction influences the cavity flow, since impinging shocks have been shown to enhance mixing of transverse jets. Utilising qualitative and quantitative methods: schlieren, oilflow, PIV, and PSP the induced flowfield is analysed. The impinging shock lifts the shear layer over the cavity and combined with the instabilities generated by the transverse jet creates a highly complicated flowfield with numerous vertical structures. The interaction between the oblique shock and the jet leads to a relatively uniform velocity distribution within the cavity

THE KINEMATIC ANALYSIS OF THE LUMBAR, LUMBOSACRAL, AND HIP JOINTS IN THE DOLPHIN KICK SWIMMING

INTRODUCTION: The dolphin kick movement is commonly used in swimming. The low back pain (LBP) while using the dolphin kick motion is complained by many swimmers and that greatly influences their performance. Cailliet (1968) stated that LBP is caused by kinematic problems in the lumbar, the hip joint and the pelvis. Thus, the kinematic analysis that was included includes the pelvis, the hip joint as well as the lumber vertebrae was necessary for the prevention of the LBP. However, underwater analysis of the dolphin kick was not enough to explain the injury mechanism. Therefore the purpose of this study was the kinematic analysis of the lumbar, the lumbosacral, and the hip joints in the dolphin kick