Air blower has been widely used in many industrial fields such as wind tunnel and large ventilation systems. Its performance is affected by operating conditions and system geometry of inpeller and duct, and these design parameter optimization is essential for the effective development. CFD analysis is carried out to investigate the air flow field characteristics with outlet total pressure in a blower system. Intake air into the impeller blade through the inlet is compressed, and then gradually discharged from the outlet with ascending total pressure, and predicted results are compared with test data. Especially this overall pressure difference in the blower system severely depends on the flow rate. These results are expected to be used as applicable design data for blower performance improvement.

In this study, numerical analysis was performed for the purpose of analyzing the flow characteristics and performance according to the change in the inflow hydrogen temperature and differential pressure of the receptacle of the hydrogen charging system. The pressure distribution and turbulent kinetic energy in the filter area were analyzed by changing the outlet pressure condition under the inlet hydrogen temperature condition, and the flow velocity change at the outlet was compared and analyzed. As a result of the analysis, as the differential pressure decreased, the flow rate at the outlet of the receptacle decreased by up to about 70% at the 2.86 MPa condition compared to the 1.86 MPa condition, and the mass flow rate decreased by about 56.5% at the maximum. It was found that the standard CV performance was not satisfied when the differential pressure at the inlet and outlet was 1.12 MPa or less under the 363K temperature condition.

Gate valves are hydraulic components used to shut-off the water flow in water distribution systems. Gate valves may fail owing to various aspects such as leakage through seats, wearing of packing, and corrosion. Because it is considerably challenging to detect valve malfunctioning until the operator identifies a significant fault, failure of the gate valve may lead to a severe accident event associated with water distribution systems. In this study, we proposed a methodology to diagnose the faults of gate valves. To measure the pressure difference across a gate valve, two pressure transducers were installed before and after the gate valve in a pilot-scaled water distribution system. The obtained time-series pressure difference data were analyzed using a machine learning algorithm to diagnose faults. The validation of whether the flow rate of the pipeline can be predicted based on the pressure difference between the upstream and downstream sides of the valve was also performed.

In this study, we propose a flow velocity evaluation scheme based on pressure measurement in pressurized pipeline systems. Conservation of mass and momentum equations can be decomposed into mean and perturbation of pressure head and flowrate, which provide the pressure head and flowrate relationship between upstream and donwstream point in pressurized pipeline system. The inverse impedance formulations were derived to address measured pressure at downstream to evaluation of flow velocity or pressure at any point of system. The convolution of response function to pressure head in downstream valve provides the flow velocity response in any point of the simple pipeline system. Simulation comparison between traditional method of characteristics and the proposed method provide good agreements between two distinct approaches.

In order to satisfy the strengthening automobile exhaust gas regulation and CO2 regulation, the development of eco-friendly vehicles is actively progressing. To cope with these regulations, research on alternative fuel vehicles is being actively conducted. Alternative fuels are one of the best ways to reduce dependence on fossil fuels and respond to emissions and CO2 regulations. Natural gas, one of many alternative fuels, contains methane (CH4) as a main component and has abundant reserves, so it is attracting attention as a fuel that can provide stable long-term supply by replacing fossil fuels. In addition, natural gas has a high octane number, so there is room for improvement in combustion characteristics when used in SI engines, and it has the advantage of reducing harmful emissions and carbon dioxide (CO2) compared to conventional fossil fuels. When using a low-pressure injector in a turbo engine, it is difficult to secure the flow rate of fuel because the pressure difference between the injector and the manifold is small. Therefore, it is necessary to develop a high-pressure injector to improve this. Natural gas is a gaseous fuel and should be developed in consideration of compressible flow, Although the use of a CNG high-pressure injector is required, it is difficult to stabilize the flow due to the Mach disk and shock wave interference caused by compressible flow. If the flow is not stabilized, it is difficult to precisely control the flow. Therefore, it is necessary to develop an injector in consideration of flow characteristics. In this paper, the flow analysis according to the shape change of the injector was conducted to improve the fuel flow rate injected from the 800 kPa high pressure CNG injector.

The change in pressure measurement according to the low pressure tap blockage rate of the Venturi flowmeter used in domestic nuclear power plants was approached numerically. Blockage rates were modeled dividing by 1/10dT to the downstream side of the low pressure tab to identify differential pressure changes. As a result, differential pressure increased in proportion to the blockage rate, and there was no change in differential pressure measurement at 10 to 40 percent with relatively small blockage rate, but the error rate of 50% to 0.3% or higher was shown.

In this study, FLUENT v.16.1 was used to investigate the compressible flow generated by the supersonic jet spewed from a high pressure tube. As the boundary condition for CFD (Computational Fluid Dynamics) analysis, the inlet temperature of air was constantly 300 K and the variation of JPR (Jet Pressure Ratio) were 5, 50, 100, 150 and the variation of tube diameter were 10, 20, 30 cm. As a result, it was confirmed that the effective range was increased as the JPR was higher, but it was confirmed that the effective range was lower than the JPR rise, and that the effective range was increased as the diameter was larger. Therefore, it is found that the tube diameter is more sensitive than the JPR among the influence factors of jet, and if the result of this study were reflected in the design of high pressure system, it will contribute to the design of the system for preventing the second accident.

Recently, reverse osmosis (RO) is the most common process for seawater desalination. A common problem in both RO and thermal processes is the high energy requirements for seawater desalination. The one energy saving method when utilizing the osmotic power is utilizing pressure retarded osmosis (PRO) process. The PRO process can be used to operate hydro turbines for electrical power production or can be used directly to supplement the energy required for RO desalination system. This study was carried out to evaluate the performance of both single-stage PRO process and two-stage PRO process using RO concentrate for a draw solution and RO permeate for a feed solution. The major results, were found that increase of the draw and feed solution flowrate lead to increase of the production of power density and water permeate. Also, comparison between CDCF and CDDF configuration showed that the CDDF was better than CDCF for stable operation of PRO process. In addition, power density of two-stage PRO was lower than the one of single-stage. However, net power of two-stage PRO was higher than the one of single-stage PRO.

This study involved the shape of water jet nozzle to promote blasting ability and an increase of projection distance when cleaning VLBC cargo hold. Simulation of water jet projection process inside VLBC cargo hold was done in both 2D and 3D environment. The result are promising since both case show the capability of water contacting the desired target.

Water discolouration and increased turbidity in the local water service distribution network occurred from hydraulic incidents such as drastic changes of flow and pressure at large consumer. Hydraulic incidents impose extra shear stresses on sediment layers in the network, leading to particle resuspension. Therefore, real time measuring instruments were installed for monitoring the variation of water flow, pressure, turbidity and particulates on a hydrant in front of the inlet point of large apartment complex. In this study, it is attempted to establish a more stable water supply plan and to reduce complaints from customers about water quality in a district metering area. To reduce red or black water, the water flow monitoring and control systems are desperately needed in the point of the larger consumers.

Axial flow fan under certain condition may stall. The rise in pressure across the impeller blade of an axial flow fan depends on the angle of attack. At a low back pressure, the air volume will be large and the angle of attack is small. In this study, the time dependent Navier-Stokes equations are numerically solved in large size axial-flow fan with groove

This study was conducted in order to evaluate three different non- invasive blood pressure measurement methods (NIBP) in comparison with direct blood pressure measurements in anesthetized dogs. Ten normal healthy Beagle dogs (mean age; 3.7 ± 1.01 yrs, mean body weight 10.2 ± 1.15 kg) were enrolled in this study. BP was measured using three different methods, i.e., Doppler (DOP), oscillometric, and high density oscillometric (HDO) methods, simultaneously, five times in each subject under anesthesia at three different locations (right, left front legs, and tail). The blood pressure value measured by the Doppler method was the closest to the value measured by the direct method. Although the accuracy and consistency of BP measured by three different non-invasive methods differed according to the method, all methods, except the conventional oscillometric method, were acceptable for monitoring systolic blood pressure in anesthetic dogs. The inter-measurement variations in DOP and HDO were minimal without affecting the consistency of the test results.

본 연구에서는 지름이 일정한 하나의 직선 관형 막을 가정하여 그 단위구간의 투과속도에 대한 물질수지를 세웠으며 이것을 기초로 하여 파이프의 정상상태 식과 함께 비선형 연립 2차 미분방정식을 이루었다. 이러한 관형 막의 압력손실을 표현한 연립방정식은 비선형이므로 Gauss-Seidel method와 같은 반복법에 의해서 해결될 수 있다. 이러한 수치해를 나타내기 위해 모사 알고리즘을 제시하였다. 또한 투과수는 운전 조건의 변화에 따라 변하므로 각 조건에서의 연립 방정식의 해를 수치적으로 적분하여 해결하였다. 모사의 결과를 검증, 해석하기 위해서 실제 중공사막과 유사한 관형 막을 사용하여 실험을 진행하였다. 본 연구에서는 중공사막을 유체가 흐를 때 발생하는 압력손실, 유량, 그리고 투과수의 관계를 분석적 방법을 이용해 제시하였고 이러한 이론적 기초를 바탕으로 실제 기공을 가진 막에 적용하여 그 정확성을 실험을 통하여 비교하였다.

본 연구에서는 자유낙하하는 직사각형 해양구조물(800×250×50mm3)의 슬래밍 충격압력 및 유동특성을 알아보고자 실험을 수행하였다. 유동장의 계측은 2-프레임 그레이레벨 상호상관 PIV기법을 이용하였으며, 자유낙하하는 모델의 충격압력은 압력계측장비(Dewatron)를 이용하였다. 모델과 자유수면간 이루는 각은 10˚와 20˚를 적용하였다. 속도장은 접수보다 이수에서 빠른 유동특성을 나타냈다. 모델 하부에서 충격압력이 가장 높은 지점인 P2 지점에서 10˚보다 경사각이 큰 20˚에서 약 6 % 상승하였다.

The triple eccentric butterfly valve has metal sheet and this study about butterfly valve ceiling is an innovative approach. But it is affected by the static pressure as well as cross-current. The damage at the valve on the pipe resulted from the reflux is due to valve leakage. This study is investigated on the triple eccentric disk and it is applied with angle and the static pressure in all cases to develop cross-current triple eccentric butterfly valves. The disc with the diameter of 300A is valve against flow velocity. The entrance pressure by flow characteristics is performed with numerical analysis. As the result, valve torque production is reduced more than the conventional triple eccentric valve and entrance pressure is decreased on the increase of valve open angle. And flow coefficient can be known to be increased.

In the present work, bismuth nanopowders with various particle size distributions were synthesized by controlling argon (Ar) gas flow rate and chamber pressure of a gas condensation (GC) apparatus. From the analyses of transmission electron microscopy (TEM) images and nitrogen gas adsorption results, it was found that as Ar gas flow rate increased, the specific surface area of bismuth increased and the average particles size decreased. On the other hand, as the chamber pressure increased, the specific surface area of bismuth decreased and the average particles size increased. The optimum gas flow rate and chamber pressure for the maximized electrochemical active surface area were determined to be 8 L/min and 50 torr, respectively. The bismuth nanopowders synthesized at the above condition exhibit 13.47 of specific surface area and 45.6 nm of average particles diameter.

가스상의 체적분율과 압력강하는 기액이상류에 대한 이해와 예측에 있어서 매우 중요한 인자이다. 또한 그것들은 산업용 대용량의 열교환시스템 및 선박에 설치되는 보일러 및 냉동시스템의 설계에 있어서 필수적인 항목이다. 따라서 본 논문에서는 파이프의 모든 경사각도에서 기액이상류 가스상의 체적분율과 압력손실을 예측할 수 있는 이론적 해석 방법을 제시한다. 여기서의 이론적 해석은 2유체 층상류 모델을 기초로 하고 있다. 또한 이론적 해석결과와 기존의 실험결과와 비교한 결과에 대해서도 제시한다.

As an attempt to develop new functional health beverage by using medicinal herb, green ginger(Zingiber officinale Roscoe), we investigated the effect of Zingiber officinale on blood pressure and regional cerebral blood flow (rCBF) of rats with Zingiber officinale extracts. Zingiber officinale extract increase rCBF significantly. The drink produced consisted of Zingiber officinale extract 1.825%, maltitol syrup 17.0%, citric aicd 0.06%, ascorbic acid 0.02%, stevioside 0.001%, ginger flavor 0.11% and water. Brix, pH and acidity of product were 13.7, 4.4 and 0.09, respectively. This drink had good score by the sensory evaluation. The above results showed that development of such functional beverage using Zingiber officinale can used as a functional material improving blood circulation in beverage industry.

The purpose of this study is to measure the changes of regional cerebral blood flow (rCBF) and blood pressure (BP) in rats, following the intravenous injection of Catalpa Ovata Water Extract (COWE). The measurement was continually monitored by laser-doppler flowmeter (Transonic Instrument, USA) and pressure tranducer(Grass, USA) in anesthetized adult Sprague-Dawley rats through the data acquisition system composed of MacLab and Macintosh computer. The result of this experiment was as following : COWE increased the changes of rCBF and BP significantly. After pretreatment with propranolol and indomethacin, the changes of rCBF were inhibited significantly, but not by L-NNA and methylene blue. Also, after pretreatment with propranolol, the changes of BP were inhibited significantly, but not by L-NNA, methylene blue and indomethacin. According to above result, it is considered that Catalpa Ovata increased the rCBF and BP, related to adrenergic β-receptor.