Monitor Points Selection in CFD FLACS for Gas Detector Placement

Gas detector first invented was in 1815 to detect the presence of the methane gas and becomes part of a safety system when it is capable to detect the gas leakage and decrease the risk of major accident occurrence. However, the efficiency of the gas detector has been questioned among industry people due to unable to measure the effectiveness of the gas detector quantitatively. Industry people has a problem on how many and where should they locate the gas detector. This study explained the very beginning steps on how to determine the number and location of the gas detector should be installed. This research simulated the gas explosion cloud by using CFD FLACS at highly hazardous area by setting the four parameters with different values of wind speed, wind direction, leak rate and leak direction. In order to optimize the placement of the gas detector, three objectives need to be achieved: 1) to obtain the fastest response time of the gas detector to any gas leakage, 2) to ensure the availability of the gas detection system in worst conditions and 3) to place the gas detector in the potentially hazardous area. The locations of the gas detector meet the objectives based on the approach applied in this study.

Buoyant vortex rings

It is pointed out that there is a fundamental difference in the behaviour of vortex rings projected upwards, according as they do or do not contain fluid which is lighter than the surroundings. A theory based on the perfect fluid approximation is developed to describe the motion of buoyant rings in a uniform fluid. The essential assumption is that the circulation remains constant with time while the buoyancy force acts to increase the impulse of a ring. This leads to the prediction that increasing the buoyancy will give a greater rate of expansion and a lower velocity of rise. The theory is extended to the case of a ring rising through a stably stratified fluid having a constant density gradient; in this case increasing the buoyancy should lead to a lower final height. The predictions of the theory have been verified by carrying out experiments in the laboratory with small vortex rings formed in water, using methylated spirits and salt to produce the density differences. The observations suggest that substantially the same analysis may be applicable to phenomena on a larger scale in the atmosphere; the velocity and final height of an explosion cloud should be determined by the buoyancy and circulation generated near the ground and the stability conditions of the atmosphere.