الفهرس | Only 14 pages are availabe for public view |
Abstract is research is to study the characteristics of jet issuing from a circular cylinder in cross air stream at different angles of injection relative to the direction of main stream. Also, the study includes the effect of the injected flow to the main stream velocity ratio. The jet nozzle used is two dimensional of 0.85 mm width and 60 mm length, machined on a hollow circular cylinder of 9.5 mm outer diameter and 7.5 mm inner diameter. The length of the cylinder is 300 mm. The cylinder was mounted across a wind tunnel test section of 300 mm width, 300 mm height and 600 mm length. The main stream velocity was varied between 8 m/s and 13.3 mis, which are equivalent to cylinder Reynolds number between 4800 and 8000. The jet has fixed Reynolds number of 3830. The injection angles were 0°, 30°, 60° and 90° relative to the main stream direction. The experiments were carried out at three ratios of jet to main stream velocities 5.2, 7.0 and 8.7. Measurements were carried out using single constant temperature hot wire anemometer mounted on automatic traverse mechanism. In order to avoid the cylinder wake circulation zone, measurements started at a distance of 3.6 times the cylinder diameter which is equivalent to 40 times the jet width. Three other measuring stations were examined at 60, 80 and 100 times the jet width. The results showed that changing the jet angle has a great effect on jet development. Also, the results indicatedinterference between the cylinder wake and the jet wake which results in creating a wake larger than that of the cylinder alone, this obstruction depends on the injection angle. The results also showed that the jet trajectory depends on the injection angle and the velocity ratio. As the velocity ratio increases, the jet decay is slower and the trajectory is more displaced from the cylinder centerline. from injection angle point of view, while increasing the angle of injection, the jet decay is faster and the trajectory is displaced more. All cases showed that moving downstream, the location of maximum velocity is more displaced and the decay is greater. Comparison with similar previous work shows good agreement. VII • |