Values Of Pressure Loss Research Articles

Investigation of Air Flow Characteristics in Air Intake Hoses using CFD and Experimental Analysis based on Deformation of Rubber Hose Geometry

In this study, the pressure loss value of air intake hose of FIAT 1.3 E6D type engine, located between intercooler and inlet manifold of the engine, was examined using computational fluid dynamics, considering geometrical deformation in a rubber material. The rubber material modelling was performed by the verification of the data - obtained through the experimental method- with ANSYS software using Mooney-Rivlin method. The rubber material modelling was performed with the aim of correctly determination of the increase in the hose diameter when subjected to pressure, since the material has the feature of elasticity. In this study, ANSYS Fluent v.18.0 software and a static pressure machine were used. The air intake into the hose took place at the pressure of 123,5 kPa and flow rate of 0,087 kg/s. A solution, independent of the number of element, was obtained in the analysis. The turbulence model used in the study is standard k-e type. As a result, the deformation-oriented pressure loss in the last geometry was found 1,85 kPa. The analyses were repeated for non-deformed geometry, and a pressure loss of 2,04 kPa was determined. At the result of the test, the geometry was seen to become actually deformed, and the pressure loss was found 1,9 kPa. The lowness of pressure loss in the deformed geometry was seen as the removal of the sharp bends that would cause local losses with the effect of pressure forces. In this study, it was determined that geometrical deformation changes the geometrical features that causes pressure loss, and leads to less pressure loss.

Gelişmekte olan laminer akışta mini kanallı soğutucu bloğun çok yanıtlı taguchı yöntemi kullanılarak optimizasyonu

Excessive heat dissipation which adversely affects the working performance of electronic equipment is an important technological problem due to developing technology, increasing power and reducing dimensions. In this context, researches on the liquid-cooled mini-channel blocks are increasing. While it is expected that the cooling blocks is desired to have high heat transfer performance with a minimum pressure drop in terms of operating costs. This requires optimization of the geometric structure in the design of the cooling block. In this study, the design of a mini channel water cooled block to be used for the cooling of a chip, has been optimized with three different materials for high heat transfer performance and low pressure losses. The performance of the mini-channel cooling block, which is designed with different materials and different channel dimensions by utilizing the Taguchi orthogonal matrix, was investigated by using Computational Fluid Dynamics (CFD). As a criterion, the pressure loss and the maximum temperature at the base were taken into consideration. Since both criteria were taken into consideration, Multi Response Taguchi Analysis was used in the optimization. Temperature and pressure loss values were evaluated and optimized by the use of different weight values.

Non-Reacting Examination on Transverse Injection Upstream of Aft Wall Angled Cavities in an Axisymmetric Supersonic Flow

Experiments on an air-fueled non-reacting scramjet test facility with four distinct aft wall angled cavity designs were performed in a Mach 1.8 flow field to explore the effects of transverse fuel injection system on scramjet combustors. Axisymmetric combustor cavity models were featured with two consecutive angles being inclined towards the downstream flow direction at the rear end. The wall mounted injector was located upstream from the cavity at a distance of 10 mm. Mixing performance within the various rear wall angled cavities were evaluated and compared with No-injection case for different injection pressures. Results revealed that the flow within the combustor was more uniform mixing compared to No-cavity configuration and was greatly influenced by injection pressures. Increase in injection pressures were characterized by enhanced mixing, greater stagnation pressure loss values and unstable flow.

ОСОБЛИВОСТІ АЕРОДИНАМІЧНОГО РОЗРАХУНКУ ВЕНТИЛЯЦІЙНИХ СИСТЕМ У КОМП’ЮТЕРНІЙ ПРОГРАМІ MAGICAD

Методика визначення втрат тиску у програмі MagiCAD суттєво відрізняється від вітчизняної, що необхідно враховувати при виконанні аеродинамічного розрахунку в процесі проектування вентиляційних систем. У статті розглянуті математичні залежності, що використовуються програмою MagiCAD при виконанні аеродинамічного розрахунку мереж повітропроводів, і проведене їх порівнянняз тими, що застосовуються у вітчизняній практиці проектування.Порівняння результатів розрахунків виконані для питомих значеньвтрат тиску на тертя та на подолання місцевих опорів (відводів круглого та прямокутного перерізів, дифузорів та конфузорів, трійників тощо). Попри суттєві відмінності в методиках обчислені значення втрат тиску є доволі близькими, значна різниця результатів розрахунків спостерігалася лише для конфузорів.

Оптимизация конструкции порошкового огнетушителя и исследование параметров подачи огнетушащего порошка

Цель. Оптимизировать конструкцию порошкового огнетушителя, исследовать параметры подачи огнетушащего порошка, провести натурные испытания.
 Методы. Экспериментальное определение текучести и остатка огнетушащего порошка в баллоне огнетушителя после его использования. Теоретические исследования значения потерь давления перед насадком-распылителем и дальности струи порошка.
 Результаты. Получены зависимости текучести огнетушащего порошка и давления перед насадком-распылителем от времени истечения огнетушащего заряда. Установлены средние значения текучести огнетушащего порошка и давления перед насадком-распылителем для исходной и оптимизированной конструкции порошкового огнетушителя. Предложена конструкция огнетушителя, которая позволяет эффективно использовать весь огнетушащий порошок, рассчитаны потери давления в конструкции с сифонной трубкой. По функциям давления и текучести перед насадком-распылителем установлено, что в предлагаемой конструкции огнетушителя без увеличения исходного рабочего давления в баллоне при увеличении подачи огнетушащего порошка дальность его струи также увеличивается. Рассчитаны значения потерь давления в сифонной трубке. Практически доказана эффективность предлагаемой конструкции порошкового огнетушителя.
 Область применения исследований. Результаты исследования могут быть использованы для оптимизации конструкции порошкового огнетушителя.

Detailed comparison of the methods used in the heat transfer coefficient and pressure loss calculation of shell side of shell and tube heat exchangers with the experimental results

ABSTRACT In this study, results of HTRI Xchanger software used in the analysis of shell and tube heat exchangers (STHE), and Kern and Bell-Delaware methods, which are the conventional methods used for calculation of shell side heat transfer coefficient (SSHTC) and pressure loss (PL), were compared with experimental data. An experimental study was considered for Heat exchanger (HE) dimensions and fluid properties from literature. Then SSHTC and PL values were calculated using Kern and Bell-Delaware methods and HTRI Xchanger software for the measured shell side flowrates. SSHTC and PL values calculated for lower shell side mass flowrates by Kern method deviated from experimental results at low ratios. In addition, deviations in high flowrates values increasingly moved away from experimental results. In the Bell-Delaware method, although low deviations were observed in the high shell-side mass flowrates, the deviations increased at low flow rates and diverged from the experimental results. The deviation of SSHTC values calculated by the HTRI Xchanger program was found to be massively independent from the shell side flowrate. In addition, as in Bell-Delaware method, it has been observed that deviations in the shell side pressure loss (SSPL) calculations increased with increasing shell-side mass flowrate. As a result, SSHTC was calculated with average deviations of + 17, −11, and + 18%, by Kern and Bell-Delaware methods and HTRI Xchanger software respectively. Similarly, shell side PL was found with + 64, −25, and −32% average deviation, respectively.

Fluid dynamics approach to airway obstruction

BackgroundFluid dynamics theory, which is a fundamental underlying concept applied to fluid management, has not been introduced to analyze the human respiratory system. We hypothesized that one of the potential mechanisms that promotes airflow limitation in patients with airway obstructive disease would be elucidated by using fluid dynamics theory. MethodsWe calculated the values of pressure loss and static pressure change under virtual tracheal stenotic conditions using the fluid dynamics approach. ResultsUnder normal conditions, the absolute values of pressure loss and static pressure change are very low. However, once airway stenosis occurs, it is confirmed that they would be dramatically elevated. ConclusionsThe fluid dynamics approach to airway obstruction is very constructive. The treatment strategy for airway obstruction and the reasons for airflow limitation are well explained by using this approach.

Transverse Injection Experiments within an Axisymmetric Scramjet Combustor

Abstract Investigations on the performance of a rear wall angled cavity with upstream transverse fuel injection in a Mach 1.8 flow field is experimentally studied in a non-reacting flow facility. The high speed flow is directed to a circular cross sectional supersonic combustor and proceeded towards the cavities having two consecutive angles being inclined towards the downstream flow direction. Wall mounted injector is positioned at a distance of 10 mm upstream from the cavity. Air is used as the injectant to simulate the gaseous fuel. The experiments are performed to explore the effect of the increase in injection pressures within various rear wall angled cavities by comparing with the ‘no-injection’ case and to finally assess the mixing performance of the flow. Transverse injection through upstream wall orifice of the cavities outlines a more uniform mixing compared to ‘no-injection’ configuration. Increase in injection pressures enhances mixing and stagnation pressure loss values.

Effect of moisture content on terminal velocity of lentil grain

One of the aerodynamic characteristics of lentil is its terminal velocity. In order to determinate the terminal velocity, was designed a vertical wind tunnel. It was fabricated based on existing methods and standards. For decreasing the non-uniformity of airflow in the vertical wind column, was used a honey comb test area with 5 mesh screens. So, a wind tunnel nozzle was designed and fabricated using Morel method with the aim of increasing airflow rate and decreasing losses due to mesh screens. The height and section area of tunnel were 1.425 m and 0.1 × 0.1 m2, respectively. The pressure loss values were calculated at different parts of tunnel and then, the required power of tunnel was determined. In this study, lentil grains of Kimia and Gachsaran varieties were separated at three groups based on their size (small, medium and large). Then, the terminal velocity was measured at 5 levels of moisture content (8, 12, 16, 20 and 24% (w.b.)) for each group. The results showed that Kimia and Gachsaran variety had the highest (7.204 m·s–1) and the lowest (6.987 m·s–1) terminal velocity, respectively. The mean value of terminal velocity increased linearly from 6.751 to 7.396 m·s–1 by increasing the moisture content from 8 to 24% (w.b.). Also, by increasing the grains dimension from small to large, the terminal velocity increased from 6.345 to 7.792 m·s–1.

Analysis of the Influence of the Heat-Absorbing Surface of an Air-Cooled Solar Collector on its Thermal and Mechanical Properties

Abstract This paper presents the analysis of existing forms of heat absorbing surfaces of air solar collectors, which gained the greatest popularity in the world. The obtained data allowed to conclude that there is a need for the development of solar collectors with air as a coolant with an improved form of heat absorber, which will reduce the operational and capital costs of solar systems and allow the efficient use of such structures in a moderate climate without additional mechanisms for the transfer of coolant. The use of computer simulation helped to compare the thermal characteristics of air-borne solar collectors of a different design. The substantiation of the expediency of installing as a heat absorber of flow turbulators in the form of a screw has been fulfilled, as well as the height of the air channel of the solar collector has been determined, in which the maximum heating of the transfer medium is observed. In addition, the loss of pressure in the air channel of the solar collector with flow turbulators was determined and the comparison of the obtained data with the values of pressure losses in the air collector of the matrix type and the air collector with V-shaped ribs was made.

Increasing the efficiency of highly concentrated coal-water fuel based on the simulation of non-Newtonian fluid flow

The analysis of further prospects for increasing the efficiency of transportation of coal-water fuel in hydro-transport systems of industrial enterprises is carried out. The mathematical model of the spatial three-dimensional flow of coal-water fuel was developed on the basis of SST turbulence model based on the solution of Navier-Stokes equation. As a result of the calculation, the values of pressure loss, flow rate and velocity distribution over the cross section of the pipeline in the straight section and in the turn were determined, which allowed determining the energy consumption during coal-water fuel transportation in the industrial hydro-transport system. The performed studies allowed us to refine the mathematical model of water-coal suspension flow and, thus, improve the patterns of influence of hydro-transportation scheme and parameters of coal-water fuel on energy consumption for its supply to enterprise consumers. By means of mathematical model of non-Newtonian fluids flow, the patterns of influence of hydro-transport system parameters and transportation modes of coal-water fuel on its energy indicators in industrial hydro-transport systems are determined. The obtained results are related to reduction of energy consumption, optimization of enterprise transport network configuration and increase of efficiency of coal-water fuel transportation to enterprise energy facilities.

Heat Engineering Test Data Obtained for the Shell-&-Tube Gas-Oil Heat Exchanger Using the Scientific Test System of the PJSC "Sumy Scientific and Industrial Association

Application of gas-oil heat exchangers (GOH) to heat up the fuel gas and cool down oil in the lubrication system of gas turbine engine of the gas blower requires safe operation of this equipment to eliminate the leakage and the mixing of actuating media and provide quick response in case of emergency. The latter is provided by the use of bimetal tubes for GOH with the safe channel (SC) connected to the automatic gas blower emergency stop system. The PJSC "Sumy Scientific and Industrial Association" has designed a prototype of the shell-&-tube GOH on the basis of bimetal ribbed tubes (BRT) with the safe channel. Therefore, the heat engineering tests of the shell-&-tube GOH based on BRT with SC are of great practical and theoretical interest and enable the generation of specific and reliable information on the prototype system. The purpose of this research was to carry out heat-engineering tests of the prototype system of shell-&-tube GOH equipped with BRT and safe channel. The obtained test data were used to plot the relationships of the influence of average logarithmic temperature pressure on the value of thermal flow transferred from the hot heat carrier to the cold heat carrier. The values of pressure loss in the tubular and intertubular zones of the heat exchanger were defined in the range of change of the flow rates of heat carriers. The values of heat resistance of the contact and those of air in the SC were obtained for the given structure of bimetal ribbed tubes used for the GOH. Heat-engineering tests allowed us to specify the mathematical model and the appropriate program used for the computation of the process of heat transfer to the GOH based on BRT with the SC.

Theoretical analyses of pressure losses in organic Rankine cycles

The thermodynamic efficiency of Organic Rankine Cycle (ORC) obtained from experimental systems has been obviously lower than theoretical results. One of the reasons is that some elements affecting the efficiency, such as pressure losses in evaporator, condenser and pipes, have not been deeply discussed and optimized. The present manuscript detailed and examined the influences of pressure losses on ORC thermodynamic efficiency. Pressure losses in ORC system were divided into three categories: High Pressure Loss of the first category (HPL1), High Pressure Loss of the second category (HPL2) and Low Pressure Loss (LPL). A formula was developed to describe the relationships between three categories of pressure losses and ORC thermodynamic efficiency. Through analyses of the formula, it is found that the adverse impacts of pressure losses on thermodynamic efficiency are very different, mainly depending on the characteristic specific volume of working fluid in certain state. Because the very different specific volume, under a same value of pressure loss, LPL mostly leads to the largest thermodynamic efficiency drop of ORC system, HPL1 does less and HPL2 does the least. The influences of LPL are normally 3–21 times larger than that of HPL1, and 30–50 times larger than that of HPL2. The conclusions will serve as a guide for engineering applications of ORC system.

ELUCIDATION OF LONGITUDINALLY GROOVED-RIBLETS DRAG REDUCTION PERFORMANCE USING PRESSURE DROP MEASUREMENTS

The need to determine affordable and environmentally friendly methods of reducing skin friction can be identified as one of the reasons contributing towards the study of the effectiveness of riblet shapes. Water tank experiments were carried out to optimize the shape and dimensions of microstructure grooves over a flat plate. The use of organized microstructures on channel walls is proposed to obtain lower values of pressure losses on smooth walls. Three shapes of microstructure grooves were investigated, with same groove height (600 μm) and five spacing dimensions (600, 750, 1000, 1500 μm), in water flows with velocities of up to 0.4 m/s. This was done for all selected types of riblet, which are fixed with the direction aligned with the flow. The experimental results showed that the size and shape of the riblets can massively incubate some of the turbulent structures formed on the surface and that will lead to a more controllable flow environment, which can result in drag reduction.

Selected problems of gas-liquid flow through the channels filled with metal foams

Open-cell metal foams are relatively unknown type of cellular material, which is increasingly being used as structural packing in the industrial equipment. The paper presents an analysis of experimental results on heat transfer and hydrodynamics of gas-liquid two-phase flow through the channels filled with metal foams. The research included the registration of temperature and pressure changes on fluid flow path. Furthermore the phase void fraction was measured and flow patterns in present in the channel were observed. It was found that in two-phase flow, both from heat transfer and hydrodynamics of flow point of view, the liquid plays the dominant role. It was also found a significant influence of flow patterns on frictional pressure loss value and phase void fraction. Whereas the flow patterns and geometry of the foam in much lesser extent influence on the intensity of heat transfer. Type of gas-liquid flow patterns primarily depends on flow conditions, including the velocity and properties of fluids. On the other hand, it wasn’t stated any significant effect of geometrical parameters of foam on the type of flow and the value of phase void fraction. Among many flow patterns observed during the study, there have been identified four basic structures: plug, semi-slug, slug, and stratified.

Numerical Simulation of the Cooling Water System of a 115 MW Hydro-Power Plant

The present case study points on the cooling water system of the Hydro-Power Plant (HPP) Bradisor, on the Lotru River in Romania. This 115 MW underground power plant is equipped with two Francis turbines. We built in EPANET a numerical model to simulate the operation of the cooling water system of this HPP, for different working scenarios. The whole hydraulic system is a complex one: it is composed of a main cooling water network fed by pumps, a water-based fire fighting network for the hydropower generators and a backup cooling water network fed from the penstock pipes. The numerical model of the whole cooling water system consists of 87 pipes, 133 junctions, 6 variable speed driven centrifugal pumps, 59 valves and 3 reservoirs. Some throttle control valves (TCV) are artificially inserted in our numerical model and are set with appropriate loss coefficients values to be equivalent to the equipments that introduce minor losses in the system and don’t exist as physical components in EPANET. Those equipments are: air-water heat exchangers (placed around the hydropower generators), oil-water heat exchangers (of heavy-duty thrust bearings, of turbines’ and generators’ guide bearings, of the 130 MVA step-up transformer), coolers of turbines’ seals and self-cleaning filters (one for each hydropower unit and another one for the transformer). The loss coefficient for each equivalent TCV was set based on pressure loss values measured in situ on each equipment. The numerical results (pressure and flow rate values) match the existing recordings. The simulations prove that by using a proper calibration of the numerical model, EPANET capabilities can be extended for more complex systems than the water distribution systems.

CFD Simulation of a Natural Circulation Helium Loop

Abstract The paper deals with a flow in a closed helium loop serving for cooling of a fast reactor. The flow in pipeline branches of the system is simulated by methods of CFD. The purpose is to find exact values of pressure losses, so that heat exchangers could be successfully designed and so that the power available for a loop drive could be optimally utilized. General approach to the simulation is presented, as well as the calculation procedure and achieved results.

LDA Study of Particulate Flow in a Channel with Deformed Surface Locations and with Flow Conditioner

Hydroabrasion in particulate flows plays an important role in various industrial and natural processes. To predict the effects of particulate flow and the resulting phenomena such as erosion/abrasion in a pipeline, channel or a fitting, it is essential to characterize the effects in a simple standardized geometry. For this purpose, it is vital to initially understand the particulate flow behavior and motion in such geometries. In the present work, two series of experimental works by application of the LDA measurement technique were successfully conducted. First, the particulate flow behavior at downstream of a flow conditioner inside a channel with square cross-section was investigated. Shorter lengths for fully development of velocity profile by using the self-constructed flow conditioner were observed. Moreover, the flow at downstream of the conditioner was modeled with the CFD tool (ANSYS-CFX V. 14.57) and the simulation results were compared and validated by the LDA experimental data. Better agreement between the simulation results and experimental data was observed in the fully developed region. However, there are some deviations due to the actual pressure loss through the experimental loop and the calculated pressure loss value, which includes some assumptions for the loss coefficients. Furthermore, the particulate flow behavior and vortex generation inside the deformed locations of a channel surface were studied in detail. With the help of the Matlab program, it was possible to calculate and visualize the velocity vectors for each measured point inside the channel accurately.

Experimental Study on Flow Friction and Heat Transfer in a Square-Duct Heat Exchanger with Winglet Turbulators

The paper presents an experimental study on airflow friction and heat transfer behaviors in a heat exchanger square-duct fitted with winglet turbulators. The experiments are carried out by varying the airflow rate in terms of Reynolds number from 4000 to 25,000. The winglets were mounted in tandem with three attack angles (α=30o, 45o and 60o), two winglet-pitch to duct-height ratios, (called pitch ratio, PR=P/H=1.0 and 1.5) and a single winglet-to duct-height ratio, (called blockage ratio, BR=e/H=0.2). Effects of the winglet parameters on heat transfer and pressure loss in terms of Nusselt number and friction factor are investigated. The experimental result reveals that the application of the winglets provides considerably higher heat transfer and pressure loss values than the smooth duct alone. The winglet at α=60o and PR=1 gives the maximum heat transfer and pressure loss but the one at α = 30o and PR=1.5 yields the highest thermal enhancement factor of about 1.49 at the lowest Reynolds number.

항공용 가스터빈 연소기 기본 설계 프로그램 개발 : Part 1 - 연소기 크기 결정

Daesik Kim, Gyong Won Ryu, Ki Young Hwang and Seong Ki MinABSTRACTThis paper shows a general development process for aircraft gas turbine combustors. As a first step for develo-ping the preliminary combustor design program, several combustor sizing methodologies using reference area concepts are reviewed. There are three ways to determine the reference area; 1) combustion efficiency approach, 2) pressure loss approach, 3) velocity assumption approach. The current study shows the comparisons of the calculated results of combustor reference values from the pressure loss and velocity assumption approaches. Further works are required to add iterative steps in the program using more reasonable values of pressure loss and velocities, and to evaluate the sizing results using data for actual combustor performance and sizes.