Research on the Influence of Axisymmetric Endwall on EAT Performance

To improve the performance of electrically assisted turbochargers (EATs), the influences of the hub profile and the casing profile on EAT performance were numerically studied by controlling the upper and lower endwall profiles. An artificial neural network and a genetic algorithm were used to optimize the endwall profile, considering the total pressure ratio and the isentropic efficiency at the peak efficiency point. Different performances of the prototype EAT and the optimized EAT under variable clearance sizes were discussed. The endwall profile affects an EAT by making the main flow structure in the endwall area decelerate and then accelerate due to the expansion and contraction of the meridional surface, which weakens the secondary leakage flow of the prototype EAT and changes the momentum ratio of the clearance leakage flow and the separation flow in the suction surface corner area. Because the tip region flow has a more significant influence on EAT performance, the optimal casing scheme has a better effect than the hub scheme. The optimization design can increase the isentropic efficiency of the maximum efficiency point by 1.5%, the total pressure ratio by 0.67%, the mass flow rate by 1.2%, and the general margin by 6.4%.

Methodology to Increase Flexibility in Inter-Region Flow Control for Urban Traffic

Perimeter control is used to regulate transfer flows between urban regions. The greedy control (GC) method takes either the minimum or the maximum for the control inputs. Although it has the advantage of simplicity for real-time feasibility, a few existing studies have shown that it can sometimes have negative impacts because of unnecessary transfer flow restrictions. To reduce unnecessary restrictions, this study provides a method that gives flexibility to ease the strict conditions of the conventional GC. First, we propose a modification as a way of granting exceptions to the flow restriction under specific conditions. Second, we develop an algorithm to determine the threshold dynamically for accepting the exception, by comparing the possible outflow loss of the subject region and the possible outflow gain of its neighboring regions. The test results show that this flexible greedy control can handle the balance between the transfer demands and the greed of regions for securing the supply level, while increasing the performance in both vehicle hours traveled and trip completion.

Investigating of Erosion-Corrosion Behavior of Carbon Steel in Egyptian Crude Oil-Water Mixture Using Electrochemical Method

An in-situ electrochemical polarization study was used to investigate the erosion-corrosion (E-C) behavior of C-steel in Egyptian crude oil-water mixture (ECWM) under mimetic different conditions. The anodic polarization responses for C-steel in ECWM are recognized active-passive region. Flow rate, sand particles and temperature increased the E-C rate. Disintegration rate to erosion rate proportion (E/C) was calculated and talked about.

Near-Wall Flow Characteristics of a Centrifugal Impeller with Low Specific Speed

In order to study the near-wall region flow characteristics in a low-specific-speed centrifugal impeller, based on ANSYS-CFX 15.0 software, Reynolds averaged Navier-Stokes (RANS) methods and renormalization group (RNG) k-ɛ turbulence model were used to simulate the whole flow field of a low specific speed centrifugal pump with five blades under different flow rates. Simulation results of external characteristics of the pump were in good agreement with experimental results. Profiles were set on the pressure side and suction side of impeller blades at the distances of 0.5 mm and 2 mm, respectively, to study the distributions of flow characteristics near the wall region of five groups of blades. The results show that the near-wall region flow characteristics of five groups of blades were similar, but the static pressure, relative velocity, cross flow velocity, and turbulent kinetic energy of profiles on the pressure side were quite different to those on the suction sides, and these characteristics also changed with the alternation of flow rate. As the flow rate was 13 m3/h or 20 m3/h, within the radius range of 40 to 50 mm, there was an extent of negative relative velocity of the profiles on the pressure side, and a counter-current happened not on the suction side, but on the pressure side in the low specific speed centrifugal impeller. The flow characteristics of profiles at the distances of 0.5 mm and 2 mm also showed a small difference.

Downslope Winds and Dust Storms in the Salton Basin

The Salton basin is a closed, subsea level basin located in extreme southeastern California. At the center of the basin lies the Salton Sea, the state’s largest inland lake, which is surrounded by a desert landscape characterized by paleo lakebed surfaces, dry washes, alluvial fans, and interdunes. Dust storms are common occurrence in this region. However, despite the regularity of dust outbreaks here, little is known about the meteorological processes responsible for these storms. Here I use observations and output from reanalysis to elucidate the meteorological controls on dust emission events in the Salton basin during 2015–18. Analysis of surface and upper-air observations, satellite data, and reanalysis, suggest that the largest dust storms in the region are associated with an upper-level low centered near the coastline of western Canada, which directs a zonal low-level jet over the region. Flow blocking by a coastal mountain range results in isentropic drawdown of air in the lee of these mountains. Once surface warming at the floor of the Salton basin is sufficient such that the density of the descending air is greater than that of the ambient air at the surface, the downslope windstorm reaches the desert floor and initiates dust emission. This process may also be accompanied by a downwind propagating hydraulic jump. These processes appear to be similar to those responsible for the strongest dust events in the Owens Valley, and may represent the main mechanisms for emission from other closed basins.

Research of sewage intake of small settlements during the period of rain and snowmelt

Introduction. The coefficients of uneven receipt of waste for settlements with a population of 1000 people used in the design practice, as determined in the process of analyzing the literature data, differ greatly in values, which can lead to significant errors in the calculations in the design of head wastewater treatment plants. At three sites located in the Leningrad Region, wastewater discharge measurements were carried out. Earlier, irregularity coefficients for wastewater in the dry season were determined and a mathematical relationship was proposed to describe fluctuations in the daily irregularity coefficient of wastewater during the year. The authors continued to work towards determining the irregularity coefficients for settlements with a population of 1000 people. Information on irregularity coefficients in the period of rainfall and snowmelt for two objects is given. Materials and methods. To measure the daily flow of municipal wastewater in the village of Bolshaya Dvor and the village of Tsvylevo, Leningrad Region, flow meters ERRAYM ERSV-540F V flow meters were used. A sample of the values corresponding to rainfall and snowmelt was compiled using the available weather archive from 15.12.2016 to 14.12.2017, determined the corresponding coefficients of daily irregularity of wastewater costs. A comparison of data of various objects. Results. The dependence of the daily irregularity coefficient of the snow melting period on the average air temperature is proposed. Results are given on the effect of precipitation and the duration of the preceding drought period on the daily irregularity coefficient during rainfall. Conclusions. The previously developed method for determining the estimated wastewater costs for small objects with a population of 1000 people has been added.