جستجوی مقالات مرتبط با کلیدواژه "rotational speed of the impeller" در نشریات گروه "مهندسی آب"

One of the most important ways to manage consumption is to reduce non-revenue water and losses in urban and rural water supply systems. The inaccuracy of the meters can have direct impact on the evaluation of loss water control programs as well as resource conservation programs thereby leading to incorrect decisions. In this paper, for numerical simulation of the effect of direct pump installation on the performance of domestic water meters, a turbine water meter of multi-jet production type is selected. It is assumed that the values of the mechanical brake torque on the impeller, such as the bearing friction drag torque, and magnetic magnitude is insignificant and can be considered as zero. The input and output flow are the fully developed in the water meter where K-ω-SST turbulent model is selected and the rotational speed of the impeller is collected at different flow rates. Comparing the numerical solution results with the manufacturer's practical experiments data, reveals the maximum error of 9.66%. Thus, the model can be used to evaluate the effect of direct pump installation on the performance of domestic water meters. As a real-world case, the water meter performance when the centrifuge pump is directly inserted into the outlet of the water meter is simulated and the results were compared with the non-pumped state. the behavior of the water meter when the pump is installed at the outlet of the water meter differs from the non-pumped mode in different flow rates. This difference is due to the change in the flow profile and the angle of impact of the water with the impeller. The results indicate that in high flow rates (more than 536 L/h) with the other same conditions, rotational speed of the impeller is less than the non-pumped state with the maximum decrease of 17% and thus the meter has a negative error measurement. However, in low flow rates (less than 75 L/h) the rotational speed of the impeller is increased almost twice more than the non-pumped state causing enlargement in meter's orders of error measurement.