Технические науки. Рубрика в журнале - Бюллетень науки и практики
Simplification and verification of o-xylene fuel mechanism
Статья научная
The increasing demand for energy due to economic globalization has led to the exploration of different types of fuels, including aromatic hydrocarbon fuels. Xylene is an essential aromatic hydrocarbon fuel and an important component of kerosene. This study employs the error propagation directed relationship diagram (DRGEP) and sensitivity analysis (SA) to simplify the reaction mechanism of o-xylene. The ignition delay time and laminar flame velocity predicted by the fuel mechanism under different w375orking conditions are compared with pre-simplified experimental data. The study proposes a mechanism consisting of 298 reactions and 64 components to describe the combustion reaction of xylene. The simplified mechanism's ability to reproduce experimental results is assessed, and the results reveal that the simplified mechanism effectively reproduces the experimental results, indicating its potential usefulness in practical applications. This study has significant implications for the development of more efficient and sustainable energy sources. By providing insights into the combustion behavior of xylene, researchers can develop more accurate models for predicting the performance of this fuel under a range of conditions. This, in turn, can inform the development of new technologies that can help meet the growing demand for energy in a more sustainable and environmentally friendly way. Overall, this study contributes to our understanding of the combustion behavior of xylene, highlighting its potential as a sustainable energy source and offering a potential avenue for further research in this field.
Бесплатно
Simulation analysis of non-concentric squeeze film damper
Статья научная
Squeeze film dampers are components that provide additional damping for rotating motors. In general, in order to achieve the best results of the squeeze film damper, it is necessary to appropriately increase the damping value, reduce the stiffness and set a reasonable eccentricity. In the process of designing the squeeze film damper, we can apply the rotor dynamics module of COMSOL software to model and simulate it, so as to achieve better simulation results and lay a foundation for the subsequent development and design of the product. In COMSOL software, in order to simplify the modeling of rotor components, we usually model squeeze film dampers based on the damping coefficient. The model calculates the damping coefficient for a short squeeze film damper and compares the results with the analytically calculated values. In addition, the damping coefficient depends on the position of the journal in the damper, i.e., the magnitude of the eccentricity. In this paper, by analyzing the dimensionless damping coefficient, bearing stiffness, journal displacement, and fluid load at different eccentricity, and plotting the fluid pressure distribution and the average oil film flow rate of the squeeze film damper, we can find the most suitable range of eccentricity and the damage-prone part of the damper, which can provide an important reference for the actual design of the squeeze film damper.
Бесплатно
Статья научная
The quality of the control system depends on various factors such as the characteristics of the controlled object, the control scheme, the form and size of interference, etc. In a control system where the characteristics of the object and the hardware and software have been basically determined, the control quality of the system depends on the control algorithm. The control algorithm will make the motion process control have better speed, accuracy and stability. The study of control law is an important part of the control system design of the entire six-degree-of-freedom test bench. The characteristics of the controlled object and the existence of interference in this control system require the designed control law to have the characteristics of strong robustness, certain intelligence, and easy implementation, so as to achieve stable and precise control of the system and achieve the control indicators required by the system. The control strategy of this six-degree-of-freedom test bench adopts Fuzzy PID control, which combines fuzzy theory with the mature traditional PID control theory and uses fuzzy theory to tune the three control parameters of PID to form a parameter self-tuning Fuzzy PID control Device. The Fuzzy PID control strategy is simulated by MATLAB simulation software.
Бесплатно
Simulation of ship trajectory in waves based on STAR-CCM+
Статья научная
The reliable ship motion trajectory signal provides a basis for six-degree-of-freedom test bench to simulate ship motion in waves. The characteristics of ship motion in waves were analyzed. Aiming at the problem of complex hull shape and large displacement at sea, the dynamic overlapping grid technique was used. Based on STAR-CCM+, the free surface was solved by CFD (Computational Fluid Dynamics) numerical simulation method. The numerical model of ship motion in waves was established, and the DFBI (Dynamic Fluid Body Interaction) method was used to simulate the ship motion in the waves. The ship’s motion trajectory was obtained in the regular and irregular heading waves, which provides important support for the six-degree-of-freedom test bench wave simulation system.
Бесплатно
Simulation of waste heat recovery from ship boiler exhaust gas
Статья научная
The heat pipe type waste heat recovery system can effectively reduce energy consumption when the ship is sailing in a polar region, so it has great engineering application value. In order to improve the design of the heat pipe waste heat recovery system and ensure that the design parameters meet the design requirements, this project has carried out a three-dimensional simulation analysis of the internal flow field of the heat pipe waste heat recovery system. Through reasonable model processing, application of boundary conditions, and the assignment of physical attributes the flow field characteristics of the key positions of the heat pipe type waste heat recovery system were obtained scientifically and effectively. The model was simulated and calculated, and the flue gas temperature distribution in the evaporator heat exchange tube, the overall temperature distribution of the waste heat recovery system, and the temperature change curve from the cold water entering the condenser to the steady state were obtained. The change curve of the thermal efficiency of the system during the temperature of the flue gas from the evaporator to the steady state.
Бесплатно
Статья научная
Recently, more and more scholars have devoted themselves to researching new methods of vibration reduction and noise reduction by manipulating the elastic waves in the structure to achieve the purpose of vibration reduction and noise reduction. To this end, a new type of ‘acoustic black hole’ structure is proposed, which reduces structural vibration while avoiding problems such as mass increase. In this paper, the vibration damping performance of the structure is mainly calculated by finite element software, and the energy concentration effect of the thin plate containing the acoustic black hole is verified by finite element analysis. A thin plate structure with four acoustic black holes is proposed. The calculation shows that the structure has obvious vibration reduction effect, and the vibration reduction effect can reach more than 20dB at high frequency.
Бесплатно
Smart counters for implementation in integrated smart grid
Статья научная
This article discusses the concept of Smart Grid and its elements, in particular, smart counters are considered that are an integral part of the intelligent power system, since these counters not only read the consumed electricity but also collect data, transmit and monitor information.
Бесплатно
Some specifications of diesel engine running on gaseous fuel
Статья научная
The paper dwells on the effectiveness the transition of diesel transport-energy equipment to the alternative gaseous fuel, as well as its specific design features. There is justified the possibility of the ignition of a gaseous fuel mixture through the assessment of dosing of the explosive charge, and its influence on the functioning of the process of a gas-air mixture combustion. There are also described the possible positive phenomena, which have sprung during the operation on gaseous fuel.
Бесплатно
South Caucasus transport corridor and potential for its development
Статья научная
The South Caucasus, as an energy-intensive region and transport corridor linking the markets of Asia and Europe, has long played an important strategic role in the trade, economic and political context of East-West relations. Within the framework of economic cooperation between the states of the Caucasus, the creation of a single automated information system for the customs control of transit is necessary for the exchange of information on goods and vehicles in real time. The implementation of these approaches will facilitate the effective utilization of transit potential of the South Caucasus Transport Corridor.
Бесплатно
Статья научная
Harnessing and further development of the transit potential of Georgia are closely linked to the country’s overall socio-economic development, effective use of its advantageous transport-geographical location and, in general, the successful functioning of the Eurasian transport corridor. The growth in the volumes of freight flows and increasing competitiveness in the transport corridor, along with other factors, depends on the effective work of customs services of the countries located across the corridors. The establishment and implementation of a Single Automated System of Customs Clearance and Control of Transit Goods will be a step forward in effective management and control of transit procedures, which will significantly reduce the time of customs clearance of transit goods and contribute to the reduction of financial costs of the economic operators.
Бесплатно
Study of a laboratory circuit with a warm baseboard in pulse mode
Статья научная
The increasing global energy demand is a problem that people have been paying attention to, people’s demand for energy is increasingly urgent, and improving energy efficiency has become a hot topic in this century. Studies have shown that pulsating flow has an important effect on heat transfer, and it has been concluded in most literatures that turbulent pulsation can enhance heat transfer in different degrees. Pulsation heat transfer is a comprehensive heat transfer process, and the best heat transfer performance can be achieved only when the thermal resistance of each part is reasonably coordinated. Based on the principle of hydraulic shock, this paper develops a device with warm substrate which can be used to increase the pulsating pressure and enhance the heat transfer efficiency of pulsating flow. Firstly, the construction scheme of the experimental device is proposed, and the working principle of the experimental device is described in detail. The complex impedance, frequency function, amplitude-frequency characteristic and phase-frequency characteristic are obtained by mathematical transformation of power supply circuit. Finally, the frequency response of the circuit is constructed.
Бесплатно
Study on heat transfer performance of non-integral capillary core sintered uniform plate
Статья научная
This paper mainly introduces the sintering process of the monolithic capillary wick and analyzes the influence of different copper powder particle size, filling rate, copper powder shape and heat source size on the heat transfer performance of the isothermal plate. The experimental results show that: (1) For the isothermal plate sintered with spherical copper powder, the capillary force of large particle size copper powder is small, but the flow resistance is also small, and the performance of the isothermal plate sintered with large particle size copper powder is better. (2) In the case of low filling rate, the isothermal plate is dried due to insufficient return fluid. In the case of high filling rate, on the one hand, the thickness of the liquid film at the evaporation end of the isothermal plate is large, resulting in additional thermal resistance. On the other hand, the thin film evaporation mode will be transformed into pool boiling mode, which will reduce the heat transfer performance. (3) Spherical copper powder sintered plate with regular shape has the best performance, while dendritic copper powder sintered plate has relatively high thermal resistance. (4) The heat source area has a great influence on the thermal resistance of the plate. Under the same heating power, the thermal resistance of the small area heat source is much higher than that of the large area heat source; The thermal resistance of sintered copper plate is lower than that of pure copper plate under two heat source areas.
Бесплатно
Study on the effect of diaphragm booster on the pulsed heat transfer of cooling system
Статья научная
This paper has developed a diesel engine cylinder liner and cooling water heat exchange enhancement device, including diesel engine cylinder liner, cylinder liner water cooler, hydraulic accumulator, check valve, diaphragm booster, centrifugal water pump, pulse valve and Conical tube. As well as the pulsating circulation system and booster system composed of equipment. The device heats the heat generated by the diesel engine cylinder liner in a pulsating circulation system through a cylinder circulator in a pulsating circulation system to exchange heat with the external low-temperature seawater. By controlling the opening and closing of the pulsating valve in the pulsating circulation system, fluid is generated in the pipe. Pulsing and hydraulically impacting the diaphragm booster connected near the pulsation valve pipeline, the fluid at the outlet of the diaphragm booster is subjected to hydraulic shock and circulates in a closed booster circuit connected to the diaphragm booster and passes through the cone during the flow...
Бесплатно
Test of the layout of the correction circuit with a plate heat exchanger
Статья научная
Pulse enhanced heat transfer technology is introduced, and a plate heat exchanger is designed. A pulsating valve is installed at the outlet of the heat exchanger to pulsate the heat medium. Pulsating and non-pulsating heat transfer tests are carried out on the same heat exchanger. On the basis of experiments, the effective temperature difference, heat flow and convective heat transfer coefficient of the heat exchanger at different pulse frequencies are analyzed by combining the theory of pulse enhanced heat transfer technology, heat transfer capacity, heat flow and convective heat transfer coefficient. Find the relationship between pulsation frequency of heat transfer effect of heat exchanger. The experimental results show that the heat exchanger has high heat transfer efficiency under the experimental conditions when there is pulsation.
Бесплатно
Testing of the model of the heat exchanger supercharger with a flat active part
Статья научная
This paper designs a pulsation-generating structure to provide pulsating flow for experiments. The relationship between frequency, flow and pulsating flow enhancement heat transfer is discussed separately. The characteristics of pulsating flow enhanced heat transfer are analyzed, and the theoretical research and engineering application of pulsating heat transfer are proposed. The scheme of the laboratory installation is developed, which is an independent circuit from the heat source with a pulse circulation of the coolant. The unit allows testing the heat exchanger-supercharger at different performance at the frequency of fluctuations of the coolant from 0.5 to 2 Hz. As a result of thermal tests, graphs of temperature changes over time in the heated and closed circuit at flow interruption frequencies from 0.5 to 1 Hz are obtained. It is found that with increasing frequency of flow fluctuations, the heating time of the coolant in a closed loop decreases by almost 1.85 times.
Бесплатно
The Process of Weaving New Types of Adras National Textile
Статья научная
This article describes our experimental research on the technology of production of a new range of national textille at the production enterprise Yodgorlik LLC in Margilan and its selling.
Бесплатно
Статья научная
Liner has a role as sealing or waterproof layer that was made to prevent water to be absorbed by the soil. A good liner is made within the minimum hydraulic conductivity (k) within the requirements of 1.0E-07 cm/s. This study was conducted to determine the extent on the difference between hydraulic conductivity (k) bentonite and termite nest ( Macrotermes gilvus Hagen) as one of the materials that have the potential to obtain small value of hydraulic conductivity (k). This research was conducted by examining the effect of hydraulic conductivity (k) value on the percentage of additives, such as bentonite and termite nest material ( M. gilvus Hagen), and then compared the hydraulic conductivity (k) values of those two materials. The variations in the additive content percentage are 5%, 15%, and 30% with laterite as a base material. Based on the results of falling head test at minimum density of 95% γdmax, the smallest hydraulic conductivity (k) value was obtained by bentonite with 30% mixed percentage level of 6.9390E-08 cm/s and the smallest hydraulic conductivity (k) value of termite nests was 1.2646E-07 cm/s with the content percentage of 5% mixture.
Бесплатно
The design of electric fire engine
Статья научная
The electric fire engine is based on the single chip microcomputer as the control core. In order to better realize the fire extinguishing function, the latest electric fire engine has added the tracking module, wireless transceiver module, etc., to realize the intelligent fire engine to detect the fire source and extinguish the flame. This design combines the principle of single chip microcomputer with the hardware and software circuit program to realize the function of automatic tracking and fire extinguishing, without the fire personnel risking their lives to carry out on-site operation. This kind of electric intelligent fire truck adds some practical small functions, brings us a lot of convenience, can better serve human beings. The main model of this design is a small toy car model with universal wheel and motor control wheel. The chassis is installed with a variety of sensors with different functions to achieve the purpose of moving forward and backward, steering and avoiding obstacles and eventually extinguishing the fire source. At the same time, the car can also realize wireless remote control. By comparing the shortcomings of the traditional fire truck, some improvements are made, the circuit diagram of intelligent control is designed, and the method of wireless control car for fire fighting is explored with the combination of practice and thinking, so as to further improve the fire truck and make it intelligent. The main purpose of this design is to reduce the fire casualties and improve the need for fire personnel to take the risk of life operation of the traditional fire truck function. Its advantages are automatic tracking, avoidance of obstacles, wireless control, measuring the source of fire.
Бесплатно
Статья научная
Among the alternative energy sources, of particular importance is the hydrogen energy industry, whose advantage over petroleum products consists in its high environmental safety and caloric content, inexhaustible natural reserves, its use in the internal combustion engines, and so on. Among the hydrogen-containing raw materials used in the fuel elements, particular attention is paid to hydrogen sulfide, which is disintegrated into sulfur and hydrogen. One of the biggest sources of hydrogen sulfide is the Black Sea, whose total volume is increasing annually by 4-9 million tons. The paper dwells on several methods for extracting hydrogen sulfide from the Black Sea basin, as well as associated difficulties. It also presents methods for the decomposition of hydrogen sulfide, of which special mention should be made on the plasma-chemical membrane technology.
Бесплатно
The energy circuit of the exhaust gas heat recovery circuit of a 25 kW diesel generator
Статья научная
The purpose of the work is to describe the installation using differential equations and obtain approximate values before the experiment. In this paper, a constructive scheme of the experimental device is proposed, and the principle of its operation is described in detail. The power circuit of the device has been drawn up. Complex impedance, frequency function, amplitude-frequency characteristic and phase-frequency characteristic are obtained by mathematical transformation of the power circuit. The frequency response of the circuit is constructed. As a result of the calculations, we will obtain the amplitude frequency response and the phase frequency response. Using the found values of the characteristics, we will build graphs and draw conclusions about how the characteristics depend on the change in parameters and why the graph lines of the graphs are exactly the way they are.
Бесплатно
