Calculating the water loss and leakage in the water distribution networks (WDNs) are performed for various reasons such as monitoring and optimizing, active control, estimating economical damage, and predicting the demand in the network development plans. In this research, two leakage calculation methods including Background and Bursts Estimates (BABE) and Minimum Night Flow (MNF) have been evaluated for a rural network in the north of Iran with a high non-revenue water (NRW) percentage of 47%. Initially, the data related to the inlet flow rate of the network and the average pressure at zone were measured using ultrasonic flow meters and pressure transmitter, respectively. Then, remote data loggers collected these data. With the water loss analyses based on the BABE method (annually) and based on the MNF technique (every 10 minutes), the average leak was found to be 1.45 and 1.105 Lit/s, respectively. Also, according to hydraulic and consumption conditions, the highest frequency of MNF occurrence was observed at 00:00 and 05:00. Moreover, the effects of Legitimate Night-time Consumption (LNC) and leakage exponent (N) were evaluated. The results indicate that determining the LNC, especially in the networks in which the domestic customers use private tanks is significantly important.

Despite the applications of the MOC for analyzing the unsteady flows, using this method in networks with variable elevations still has many challenges. In this paper, by developing modified correlations as a computer code, the possibility of analyzing inclined pipelines has been evaluated. For validation and calibration, the results of MOC were compared with the results of EPANET software as well as experimental data. To extract experimental data, the water network of NIT with a constant head of 7 m three loops, and four inclined branches were employed. While evaluating the capabilities of the developed computer code, the results show that for all pipes, as the number of pressure fluctuations in a specific period increases, the intensity of the pressure fluctuations decreases, and the damping speed increases as well. Moreover, in inclined pipes, unlike noninclined pipes, the intensity of pressure fluctuations will increase as the elevation increases and the cross-sectional distance from the transient event increases as well. The evaluation of the effect of space steps on the accuracy of the solution to the MOC shows that in the study network, considering 20 segments for each pipe, the fastest response time with an error of less than 1% is obtained.

No abstract

A jet engine that works near the ground and generates high thrust at low speed can experience the flow separation from the ground surface up to its inlet and, as a result, the formation of a famous vortex. This vortex extended from the ground surface to the fan inlet is known as the inlet vortex. In the present study, a jet engine model scaled down by 1/30 relative to the real jet engine with 3 million hexahedral elements is simulated using Computational Fluid Dynamics (CFD). The obtained results agree with empirical relationships, and the inlet vortex can be analyzed in scales much lower than the original prototype. Also, the inlet vortex gets weakened by increasing free stream velocity and completely degraded at higher velocities. By understanding how this phenomenon occurs and can be dealt with, the Foreign Object Damages (FOD) such as compressor surge, fan vibration, and particle ingestion into the engine core can be prevented.

Limited water resources, especially in Iran, which has an arid/semi-arid climate, highlight the need for accuracy in managing and controlling the consumption of this vital fluid. Although many approaches have been developed to reduce Non-Revenue Water (NRW) in water distribution systems, less attention has been paid to optimal prioritization for water meter replacement. In this research, an algorithm has been presented for the purposeful replacement of customers’ water meters to increase the company’s revenue. Gavankola village has been selected as a rural network in northern Iran with a high NRW rate (58%) as a case study. Examining the customers’ water consumption in 20 periods, it was found that after replacing the water meter, the billed metered consumption (BMC) doubled and the revenue from it increased up to 5 times. Moreover, the study of two economic indicators and NRW revealed that class C water meters are less economical than class B water meters, even though they more effectively reduce apparent losses.