Inlet Pipe Research Articles

Acoustic performance and modal analysis for the muffler of a four-stroke three-cylinder inline spark ignition engine

This work presents a concise analytical report on four suggested design modifications (geometrical configuration of the resonating chamber) of a practical muffler model based on acoustic performance and reduction of back pressure. The existing model shows a very low acoustic transmission loss (15.8 dB) with a back pressure of nearly 2.52 × 105 Pa. The second proposed model provided better attenuation of 23.2 dB transmission loss but produced more back pressure (2.70 × 105 Pa). Modification of the second model by tapering of the inlet pipe's outlet accounted for the reduction in back pressure to around 2.30 × 105 Pa and increased the noise attenuation level by 1.2 dB. More significant attenuation of noise (14.8 dB) was observed in the fourth model without any back pressure. The fifth model produced the highest attenuation of 57.1 dB as compared to the other four models with undesirable highest back pressure around 2.83 × 105 Pa.

Design of an airflow model for railway brake components testing

This article is focused on designing, preparing and solving the air flow model of an inlet pipe of ventilation of test bench for disc brake testing. In the first part, the importance and methods of testing brake components are discussed, and advantages offered by simulations in this field are presented. In the next part, the ventilation of the test bench and its requirements are described. Based on these assumptions, the boundary conditions for CFD simulation are set and the model has been solved. The results are presented and discussed in the final part.

The height of the pumping unit suction pipe inlet relative to the riverbed bottom

Currently, 78% of all irrigated land in Uzbekistan is provided with water by pumping stations and installations. The water sources of most pumping stations are rivers and irrigation channels that transport a large amount of bottom and suspended sediments. Due to the lack of consideration of bottom sediments moving in the form of ridges, when installing the pumping units suction pipeline, during their operation, these bottom pumps flow from the water intake source in the interior of the units. As a result, intensive waterjet wear of the flow part and the impeller of the pumps occurs. This leads to an intensive reduction in the main parameters of the pumps, as well as reduces their repair period. Currently, this is one of the major problems of pumping stations that take water from the Zarafshan river, as well as those operating on the Karshi, Amu-Bukhara, Amu-Zang and Jizzakh main channels. Laboratory studies were carried out on the experimental installation to determine the height of ridges with different granulometric composition of bottom sediments. As a result, a formula was obtained for determining the height of the ridge, taking into account the heterogeneity of ridge forms. Based on the obtained formula, a method for setting the height of the pumping unit suction pipe inlet relative to the riverbed bottom is recommended. The application of the proposed method does not allow bottom sediments to enter the inner part of the pumps, as a result of which their intensive abrasive wear decreases, the inter-repair period increases, while maintaining its main parameters for a long time.

Analysis of Crack Growth in the Wall of an Electrolyser Compartment

Electrolysis units are widely used in different branches of industry. They are high-pressure tanks, each having a chamber and electrodes placed therein, which are arranged in assemblies, a cover as well as an inlet and outlet pipes. High requirements are imposed on their technical characteristics, confirming the urgency of the problem of improving calculation methods. To simulate the kinetics of the thermally stressed state in elements of power plants with complex rheological characteristics of the material and taking into account its damageability, a special technique and software complex have been developed on the basis of the finite element method, which allow solving a wide class of nonlinear nonstationary problems in a three-dimensional formulation with simultaneous consideration of all operating factors. The kinetics of the crack was studied using the method of calculating the survivability of structural elements, which is based on the principles of brittle fracture mechanics, while the plastic zone at the crack tip is assumed to be small compared to the crack size, and the crack kinetics is determined by the stress intensity factors at crack tips. The technique is based on calculating the kinetics of the crack to its critical dimensions, when an avalanche-like destruction of a structural element occurs, or a crack grows through the thickness of the element. The kinetics of a semi-elliptical crack emerging on the inner surface of the cell wall was studied under the action of static and cyclic loading. With the use of the developed technique, computational studies of the thermal stress state of the upper part of the electrolyser cell were carried out. The results obtained show that the cylindrical part of the cover is the most loaded. There have been carried out studies of the development of an internal surface semi-elliptical crack, which originated in this zone. It was found that with a small number of cycles per year, the crack will grow for a long time to a certain depth, then the rate of its growth from static loading will increase so quickly that the growth of the crack from cyclic loading can be neglected.

Burner development for efficient combustion of biogas

Now in metallurgical production energy resources demand is almost completely satisfied by gaseous fuel. Biogas obtained during organic waste processing is considered as an alternative and cheaper type of fuel. The experience of biogas application has shown that in most modern burners decrease of efficiency and limitation of the range of load regulation is observed. To apply biogas in an industrial environment, it is necessary to develop burners and the methods of its combustion, which provide a high combustion efficiency, as well as a higher energy conversion efficiency. The authors have used the results of gas analysis of biogas obtained in the process of anaerobic decomposition process of organic waste in the reactors of a bioenergy plant. Methods of mathematical statistics with the use of regression analysis of experimental data were used to assess the indicators of the energy efficiency of the gas burner. The possibility of using biogas and landfill gas in the process of roasting, blast-furnace smelting, production of rolled products and steel, as well as heat treatment of metal has been experimentally proven. The properties and composition of biogas at the outlet of the methanogenesis reactor of the bioenergy plant “EcoVoltAgro” are described. A new design of a gas burner is proposed. In this model the efficiency of mixture formation and the completeness of combustion of the flow of a methane-containing gas mixture are significantly increased (up to 32 %) due to the effect of rotation of the perforated pipelines of the gas inlet pipe. On the basis of the results of the full-scale experiment, the optimal values of the gas-air mixture supply rate, the temperature of the supplied air, the volume fraction of methane were determined in order to obtain the largest width of the zone of deviations of the permissible concentrations of carbon dioxide. The use of the designed gas burner provides energy-efficient combustion of biogas in metallurgical furnaces, kilns, and dryers, as well as in any steam and hot water boilers.

Factors influencing the removal of fine non-cohesive sediment by vortex settling basin at small river abstraction works

Diverted sediment causes a wide range of problems at small diversion works. The difference in water levels between low flows and floods, low investment capital and presence of cohesive sediment and fine non-cohesive sediment coupled with a requirement for a high level of supply assurance makes the design of such hydraulic structures complex. Vortex settling basins (VSBs) offer a promising alternative to conventional settling structures or hydro-cyclones. In the current study, parameters affecting the trapping of particles >75 μm were numerically investigated using ANSYS Fluent and were validated by physical modeling. It was established that the inlet velocity needs to be maintained at 0.26 m/s, the underflow to inflow ratio should be between 0.05 and 0.10, the cylinder height to cylinder diameter ratio should be greater than 0.5, and the positioning of the inlet pipe to cylinder height ratio should be greater than 0.7, with a cone of slope ratio of 2:1 (V:H) and the cylinder diameter to inlet diameter ratio should be 8.2. These parameters form the basic design guidelines for VSB use at small diversion works (<100 L/s duty capacity).

Transient flow simulation, analysis and protection of pipeline systems

This paper investigated the problems and impacts of transient flow in pipeline systems due to pump power failure. The impact of different protection devices was presented to assure surge protection for the pipeline system. A model via Bent-ley HAMMER V8.0 Edition was employed to analyse and simulate hydraulic transients in the pipeline system, and protec-tion alternatives were studied. Surge protection included using only an air vessel, using an air vessel and two surge tanks, and employing five air ves-sels and vacuum breaker. The obtained results for pressures, heads, and cavitation along the pipeline system were graph-ically presented for various operating conditions. Using five air vessels with vacuum breaker valve as surge protection proved to be more effective and economical against pump power failure. Changing the flow density did not have a significant impact on the pressures. For protection with an air vessel; it was concluded that the value 40% of the original diameter for inlet pipe diameter of air vessel, and the value of 2/3 of original pipe diameter were critical values for the transient pressures. Cast iron pipes proved to be the best pipe material for all studied volumes of the air vessel. For protection with an air vessel and two surge tanks; as the inlet pipe diameters increased the maximum pressures in-creased and the minimum pressures decreased. Regression analyses were performed obtaining equations to predict the pressures according to the inlet pipe diameter, the area of surge tank, and the pipe diameter.

Effect of oxygen and steam on gasification and power generation in industrial tests of underground coal gasification

To optimize the gasification process and improve the underground coal gasification (UCG) technology for power generation, a pilot project of UCG integrated with the power generation was built in the abandoned mine “Ankou”. The UCG industrial tests with different oxygen concentrations of oxidant along with the pulsed injection method, and power generation experiments using UCG syngas were conducted. The results indicate that a decrease in the rate of air blowing for a short time exhibited a limited influence on syngas production, but a change in the amount of oxygen injection presented an obvious effect. With the increase in the oxygen concentration in the agent, the H2 content, combustible components and calorific value of syngas, flow ratio, and the consumption of coal, steam and oxygen increased, along with a rise in the gasification efficiency after an initial drop. The oxygen-enriched gasification trials showed higher air consumption, lower consumption of coal, steam and oxygen, and a low combustible components and calorific value of syngas compared to the gasification tests of the oxygen-enriched steam. The evaporation of ground water and coal moisture in the UCG panel provided steam for the oxygen-enriched gasification process, and its utilization rate was about 6–32 wt%. From the characteristics of UCG syngas, the technical transformations such as exhaust gas booster combustion control, high energy ignition, low pressure intake, expansion of the air, and gas inlet pipe diameter were carried out on the existing gas generator sets. The effectiveness of the measures was verified by the power generation experiments.

Process Dynamic of Two-Thermal-Tank-Series with Dead Time

The multi-tank-series system could come up the problem of instability due to dead-time. The goals of this work are to study the dynamic behavior of Two-Thermal-Tanks-Series (TTTS) with dead time through the open loop experiment in laboratory, and to propose the new-module of fundamental chemical engineering practicum in field of process dynamic for undergraduate program. The two stirred-tank-heaters @10L were designed for heating of water fluid. Both of tanks were designed overflow to maintain their volume constant. The gate valve was installed in the inlet pipe of Tank-1 to adjust its volumetric flowrate (f). The inlet temperature of Tank-1 (T1), the liquid temperatures in Tank-1 (T2) and Tank-2 (T3) were measured by thermocouple multi-channels. The volt-ampere-regulators were used to adjust the electrical energy in Tank-1 (q1) and Tank-2 (q2). The mathematical model was solved and rigorously examined in Xcos/Scilab. In order to study the dynamic behavior of TTTS, the inlet flowrate disturbance was made based on step input change. According to our investigation in laboratory and open loop simulation, both Tank-1 and Tank-2 gave stable responses, the model’s responses showed the closed and similar trend with laboratory’s responses, and time delay of about 30 seconds has been found in Tank-2.

JUSTIFICATION OF CHANGE IN CASE OF VACUUM PUMPS

Milk production is closely related to the milking process. The operations that are involved in this process require high responsibility and are quite laborious. The economic efficiency of the milking process depends not only on the qualifications of the operators, but to a large extent is determined by the technical perfection of the means of mechanization that are used. After all, the vacuum pump, which is part of any milking installation, has a significant impact on the productivity of the latter. The operation of the executive elements of the milking machines, as well as the transportation of milked milk, depends on the amount of air taken. The perfect design of the vacuum pump affects the energy consumption of the milking process. The analysis of vacuum pumps used in the technological process of machine milking is made. Research and literary sources indicate that mechanical rotary vacuum pumps are most widely used, this is explained by a number of technical and economic indicators. The specific energy consumption of a rotary vane vacuum pump depends on the value of the set working vacuum and the rotor speed. In most rotary vane vacuum pumps, the housing design provides for the movement of air through the inlet pipe to the inlet port and does not fill the space between the two blades as much as possible. If the air is escaping, it cannot be quickly emitted through the outlet window. These disadvantages are eliminated by the fact that a transverse groove is located at the end (in the direction of movement of the rotor) of the inlet window. To effectively remove air from the pump, the outlet window, at the beginning (in the direction of the rotor movement), has a transverse groove, the dimensions of the grooves are 4/5 of the width of the vacuum pump housing and less than 1/2 of the width of the corresponding window. The proposed design of the body of the vacuum pump makes it possible to increase the productivity by 7-12% and reduce the power consumption for the drive by 8-10%, in addition, there is a decrease in the heating of the body to 67-74 °С.

Analysis of experiments on condensation induced water hammers at KGU test facility by WAHA code

Experiments at the KGU test facility, devoted to steam induced water hammers were analysed with the WAHA code. Test section of the KGU test facility is slightly inclined horizontal pipe of 3 m length and of 64 mm inner diameter. Subcooled water was supplied to the pipe inlet, pipe outlet was connected to separator vessel. Upper part of separator vessel was connected to steam source. Experiments were performed for different system pressure, different water subcooling and different mass flow rate of water supply. The WAHA code has been developed for simulation of condensation induced water hammers in pipelines. It is based on two-fluid approach, WAHA numerical scheme is based on Godunov numerical methods. Numerical simulations of the KGU tests revealed disagreement between numerical and experimental occurrences of water slug formations and water hammers events. Methodological calculations with variation of heat transfer to subcooled water showed, that this value significantly influences on water slug and water hammer formation.

Pengaruh Modifikasi Pipa Masukan Bahan Bakar Oli Bekas Berbentuk Spiral Terhadap Performansi Burner Tornado Api

The need for fuel in Indonesia is a serious problem in human life in the future. Various efforts are being made to find alternative fuels. One that is currently being researched as an alternative fuel is lubricating oil (oil). Several studies have been carried out in the context of developing this used fuel oil. Used oil when using the standard burner used in previous studies has an impact on the amount of smoke and low temperature, because the oil that goes to the burner is still pure oil. This research tries to modify the oil input flow in the form of a circular spiral. The difference between the burners that will be made with previous studies is in the oil intake hose. The oil inlet pipe in this study will be made in a spiral shape. The results showed that the modification using a spiral pipe had a higher temperature of 397 0 C compared to without using a spiral pipe which was 381 0 C. In addition, the heating rate using this spiral pipe is greater, namely 302400 Joules. So it can be concluded that the burner performance with spiral pipe modification is higher than without using spiral pipe

An Experimental and Numerical Analysis on the Dynamical Behavior of a Safety Valve in the Case of Two-phase Non-flashing Flow

Pressure Relief Valves (PRVs) are key elements of any hydraulic system in the process industry, especially in chemical plants or hydraulic power transmission systems. Their task is to maintain the system pressure beneath a prescribed maximum pressure and vent the excessive fluid in an emergency scenario. This paper addresses the static and dynamic behavior of a Direct Spring-Operated PRV of conical shape in the presence of two-phase non-flashing flow, that is, water-air mixture. First, experimental results on the force and discharge characteristics of such a valve in a wide range of the air-to-water mass fraction are presented. Our test facility includes a custom-designed PRV with 42.5 mm inlet pipe diameter, an inlet pressure up to 6.6 bar(g) and a maximum lift of 10 mm. Additionally, the empirical results on the static characteristics, notably fluid force on the valve disc and discharge coefficients are reported as a function of the liquid mass fraction and valve lift. In the second part of the paper, we present the development of a Matlab-based simulation tool that is capable of predicting the dynamics and stability of such a valve in the case of two-phase, non-flashing, frozen-mixture flow. Moreover, the effect of system parameters, such as spring stiffness and reservoir capacity are recorded. Finally, we also present results on the stability of the opening and closing the multi-phase flow influence on the stability of the blowdown process.

АКТУАЛЬНОСТЬ МОДЕЛЕЙ ЗАГРЯЗНЕНИЯ ДЛЯ ДИАГНОСТИКИ СОСТОЯНИЯ ПЛАСТИНЧАТЫХ ТЕПЛООБМЕННИКОВ

The article analyzes various theoretical approaches to describing the processes of formation of scale layers on the working surfaces of heat exchangers. The main tasks include analyzing existing models of contamination of heat exchange channels, determining the main mechanism of salt deposition on the heating surface of plate heat exchangers of heat supply systems, determining the main factors that determine the intensity of salt deposition on the working plate in accordance with the dynamics of heat and hydraulic processes in heat exchange channels formed by corrugated plates, as well as forming trends for further research. The article presents the main results of research devoted to the study of contamination processes on heating surfaces. Inaccuracies in the proposed approaches to describing the nature of the formation of salt deposition layers are identified. By generalizing existing approaches to the mathematical description of pollution processes, the main assumptions are revealed when describing the processes of salt deposition on working plates. A hypothesis is proposed about the influence of the location of channels relative to the inlet pipe on the uniformity of the flow distribution between parallel channels in the device. There is a fairly large gap between the existing computational methods for modeling pollution processes and the actual distribution of scale layers during the operation of heat exchange equipment of heat supply systems

Studies of the process of heating air in the inlet pipe for starting a diesel engine at low temperatures

Starting a diesel engine at low ambient temperatures presents significant difficulties due to low temperature of the air charge; increased resistance due to increasing viscosity of the oil, turning the crankshaft and moving other kinematically connected parts; deterioration of fuel atomization conditions; enhanced heat transfer to the cylinder wall; loss of part of the air charge. This article is devoted to experimental studies on heating the air at the inlet of a small-sized 1H9,5/8,0 diesel engine with air cooling at ambient temperatures of -20 ° C, -40 ° C, -60 ° C. As the result of experimental studies, the time of stationary values of air temperature in the combustion chamber, as well as in the inlet and outlet pipes was determined. Temporal patterns of changes in air temperatures in the combustion chamber, in the inlet and outlet pipes when scrolling the diesel engine with a starter are obtained.

DPCFoam: an OpenFOAM solver for corrosion-thinning prediction caused by dissolved particles

A new solver for corrosion-thinning prediction caused by dissolved particles named DPCFoam has been developed in the framework of the open source CFD toolbox OpenFOAM. This paper uses mass transfer control mechanisms to achieve particle dissolution and concentration diffusion processes. Moreover, experimental flow-accelerated corrosion (FAC) data sets were gathered from the literature and a FAC model was proposed. Then, a genetic algorithm was adopted to obtain the optimal coefficients of the empirical FAC model. In addition, DPCFoam was developed by implementing the particle dissolution, concentration diffusion and wall corrosion-thinning prediction (both empirical and theoretical FAC models) processes based on C++’s class inheritance and template techniques. Finally, the dissolution model was validated with a case of the dissolution of alumina in cryolite melts, and an air cooler inlet pipe with water injection was used as a case to validate the DPCFoam solver. Satisfactory results show that DPCFoam can be used to predict the wall corrosion-thinning rate due to the dissolution of corrosive particles.

Development and research the electronic control system for gas engines converted on the basis of diesels

The object of research is an electronic microprocessor control system for gas internal combustion engines with spark ignition for operation on liquefied petroleum gas. The system consists of two main subsystems, the accumulative power supply common rail LPG injection subsystem and the contactless electronic ignition subsystem with a movable voltage distributor. In addition, the control system also includes a subsystem for controlling the filling of the cylinders with the charge of the working mixture, consisting of a throttle valve and an idle speed regulator with a conical damper. The control system, depending on the software version, is capable of providing group or sequential injection of liquefied petroleum gas into the inlet pipe of each cylinder in the area close to the inlet valve. Such a control system can be used when converting (re-equipping) both new diesel engines into spark-ignition gas engines, and those that are in operation. The feasibility of such a conversion is to reduce operating costs with powerful vehicles for diesel fuel, by replacing it with cheaper and environmentally friendly liquefied petroleum gas.To test the efficiency of the control system, a D-240-LPG-«B» model gas engine was developed and manufactured to operate on liquefied petroleum gas. The gas engine was converted on the basis of the D-240 transport diesel engine (atmospheric, four-stroke, liquid-cooled, 4-cylinder engine with a piston diameter of 110 mm and a stroke of 125 mm). Reducing the compression ratio of the diesel engine was achieved by modifying a semi-closed diesel combustion chamber of the TsNIDI type into an open combustion chamber in the form of an axisymmetric «truncated cone». For efficient control of three subsystems of the D-240-LPG-«B» model gas engine, an electronic microprocessor control unit of the Avenir Gaz 37 «B» model was developed and manufactured. The tests carried out on the D-240-LPG-«B» gas engine with the Avenir Gaz 37 «B» control unit showed the efficiency of using the electronic microprocessor control system.

Optimization of mixing in a Chinese dome digester for tropical regions

Optimization of mixing in a Chinese dome digester for tropical regions

Transient flow field and performance analysis of a claw pump for FCVs

The claw-type hydrogen pump has been applied in fuel cell vehicles (FCVs) because of its compact structure, high reliability, and oil-free quality. In this study, a three-dimensional transient computational fluid dynamics (CFD) modelling of a claw-type hydrogen pump used in FCVs was established. Hexahedral structured grids were generated and updated at an increment of 3° in rotating angle to ensure the mesh quality of the whole solving process. The leakage of radial clearance (RC) and axial clearance (AC) was considered. The presented modelling and simulation methods were validated by operating a claw pump at different pressure ratios. The pressure and velocity vector fields in both AC and middle plane, along with the mechanism of the fluid field distribution were analyzed in detail. The in-depth relationship amongst the fluctuation of discharge pressure, outlet mass flow rate and discharge area during the whole working process was revealed. P-θ and V-θ diagram of the whole operating cycle were analyzed. The influence of AC and RCs respectively on the volumetric efficiency of a claw pump was compared and evaluated. It is concluded that back flow in suction pipe happened near 360° as part of the discharge chamber was cut off from the exhaust port and high pressure gas from carryover flowed back into the inlet pipe. The pressure increase during the displacement process, theoretically zero, is actually significant and even comparable to the pressure increase during the compression and discharge process. In addition, volumetric efficiency is most sensitive to axial clearance, followed by radial clearance between rotor and casing, while radial clearance between the rotors has the least influence.

Numerical approach for prediction of turbulent flow resistance coefficient of 90° pipe bends

In the present study turbulent flow in a circular cross-sectioned 90° smooth-walled pipe bend has been investigated numerically. The geometry of the model consisted of three sections: a straight inlet pipe of length 52 diameters, a 90° bend with radius of curvature 1 diameter, and a straight downstream pipe of length 52 diameters. Reynolds numbers from 5,000 to 120,000 were considered. The numerical model was developed using COMSOL Multiphysics and all turbulent flow simulations were performed using the standard k- ε turbulence model. The main objective of this work was to estimate the resistance coefficient of pipe bends using not only pressure drop but also information of the flow behavior far downstream in the outlet pipe. Wall static pressure and velocity fields of the secondary flow were illustrated to provide information of the flow behavior in the bend and downstream of the pipe bend. Furthermore, swirl intensity of secondary flow was presented in order to describe its behavior as the flow develops in the outlet pipe. Estimations of resistance coefficient were calculated and compared to other studies. It was found that the procedure used in this study is a viable method for a more accurate estimation of resistance coefficient values for turbulent pipe flows containing 90° bends. For best accuracy in either experimental or computational analyses, it is recommended that pressure in the downstream tangent be measured at no less than fifty diameters downstream of the bend to avoid influence of the secondary flow.