Influence Of Design Parameters Research Articles

Study on propellant utilization in pulsed plasma thrusters

Low efficiency can restrict the application of a pulsed plasma thruster. Low propellant utilization is one of the main reasons of this low efficiency. To improve pulsed plasma thruster efficiency, the influences of design parameters (capacitor initial voltage, electrode gap and electrode width) on the propellant utilization of a pulsed plasma thruster are studied. Because the propellant utilization of a pulsed plasma thruster is difficult to measure, a model that can simulate the ablation and ionization processes of a pulsed plasma thruster is established. Based on the model, the propellant utilizations under different working conditions of pulsed plasma thrusters are estimated. The results show that, the propellant utilization of a pulsed plasma thruster decreases as the capacitor initial voltage increases under a given capacitance and increases as the capacitor initial voltage increases under a given discharge energy. In addition, the propellant utilization is not affected by the electrode gap and increases as the electrode width increases. The simulation results are explained and analyzed. According to the analysis, the design parameters affect the propellant utilization of a pulsed plasma thruster by affecting the electric field intensity and the neutral gas density between the electrodes. The increase in propellant utilization may decrease the energy utilization in a pulsed plasma thruster. This study can provide references for the design of high-performance pulsed plasma thrusters.

Dynamic Instability Analysis of a Spring-Loaded Pressure Safety Valve Connected to a Pipe by Using Computational Fluid Dynamics Methods

Abstract As the ultimate protection of a pressure system, pressure safety valves (PSV) can respond in an unstable manner in the form of flutter and chatter, which will affect service life, reliability, and performance. In order to study the dynamic instability caused by multisource forces including the flow force, the spring compression force, and the pressure wave forces, a high-fidelity computational fluid dynamics (CFD) model of the system is proposed. A complete CFD model, incorporating the PSV, connected pipes, and the pressure vessel, is developed, in which advanced techniques in Fluent using User Defined Function (UDF) and Dynamic Layering method are combined to allow the PSV to be coupled to the system dynamics. Based on this model, the valve's opening and reclosing process is monitored to examine the influence of design parameters on the dynamic instability of the PSV. Specifically, the propagation of pressure waves along the connecting pipes is successfully captured, helping to assess the instability mechanism and provide the ability to optimize the design and setup of pressure relief systems.

Band Gap and Vibration Reduction Properties of Damped Rail with Two-Dimensional Honeycomb Phononic Crystals

The prevention of environmental vibration pollution induced by train operation is one of the inevitable problems in the construction of urban rail transit. With the advantage of flexible adjustment, phononic crystals (PCs) have a broad application prospect in suppressing elastic wave propagation of rail transit. In this paper, a damped rail with two-dimensional honeycomb PCs was proposed, and its band structure was analysed with FEM. Then, a parametric study was used to investigate the influences of design parameters of the honeycomb PCs on its band gap property. Furthermore, with a 3D half-track model, the vibration reduction property of the damped rail with honeycomb PCs was discussed. The results show that the damped rail with honeycomb PCs has an absolute band gap in the frequency range of 877.3–1501.7 Hz, which includes the pinned-pinned resonance frequency of the rail internally. Reducing the filling fraction and elastic modulus of the matrix can obtain an absolute band gap in a lower frequency range but also bring a narrower bandwidth. The decrease of scatterer density leads to higher boundary frequencies of the absolute band gap and descends the bandwidth. In order to obtain an absolute band gap which can suppress the pinned-pinned resonance of the rail and keep a wider bandwidth, the filling fraction is suitable to be about 0.5, and the elastic modulus of the matrix is proposed to be not more than 0.6 MPa. Metals with heavy density can be used as the scatterer to obtain a better vibration reduction effect. It is hoped that the research results can provide a reference for the application of PCs in track vibration reduction.

A pathway towards sustainable development of small capacity horizontal axis wind turbines – Identification of influencing design parameters & their role on performance analysis

Presently small wind turbines are receiving greater attention, due to the extensive promotion of decentralized power generation in a sustainable way by national and international organizations. However, there are many obstacles in commercializing these turbines on a large scale due to lower efficiencies of turbines associated with high vibrational losses, lack of technical knowledge with the manufacturers, cost criteria and lack of awareness among the end-users. This paper reviews the research works done in the design and development of small wind turbine blades, including diffusers and winglets addition. Performance & parametric analysis of airfoils, blades & wind turbines are presented comprehensively. Impact of maximum power point technique, effects of ambiance on the turbine performance, environmental impacts of small wind turbines and some novel concepts are presented in this review. Future research works to enhance the efficiency of small wind turbines using materials with high strength to weight ratio would pave the way for efficient utilization of available wind energy in the earth’s crust.

Methodology for assessing the energy efficiency of separating methods for wax raw materials

The methodology for assessing the energy efficiency of operating actions during the separation of organic contaminants of wax has been developed. Promising methods of separation of media with complex types of bonds are proposed. The dependences characterizing the energy efficiency of separating methods for the wax raw materials have been determined. Mathematical models are obtained in the form of quadratic polynomials characterizing the influence of design parameters on energy characteristics. The influence of the design parameters of the device and the technological properties of the exposed materials in the form of wax raw materials on the values of active and reactive power has been proved. It has been established that the most rational measure for increasing the energy characteristics of devices for separating wax raw materials is to optimize their design and technological parameters.

Primary parameters design method for distributed electric propulsion unmanned aerial vehicle

Distributed electric propulsion technology brings new ideas to the design of unmanned aerial vehicle(UAV), such as improving aerodynamic efficiency and propulsive efficiency, and new concept of vertical/short takeoff and landing configurations. However, compared with conventional UAV, the propulsion system of distributed electric propulsion UAV is more complex, which brings difficulties and challenges to the design of distributed electric propulsion UAV. Based on its special aerodynamic/propulsive coupling characteristics, this paper studies the design method and process of primary parameters of distributed electric propulsion UAV. A short takeoff and landing UAV with distributed electric propulsion system is taken as an example for the conceptual design and primary parameter design, and the influence of design parameters on the takeoff mass and endurance is analyzed. Finally, the validity of the established design method is verified by the flight test of the prototype. Results indicate that the distributed electric propulsion system accounts for more than 20% of the takeoff mass; the electric ducted fan efficiency, mass specific power of the motor, mass specific power of the electronic speed controller and the resistivity of power wires are the most significant design parameters that affect the performance of the UAV; with the improvement of technologies, the takeoff mass is expected to be reduced by more than 20%, and the endurance is expected to be increased by more than three times.

The influence of design parameters on the pressure in the extruder for the production of sapropelic feed

Currently, agriculture is an intensively developing industry. To provide the population with meat, milk, and wool, the volume of livestock products is increasing, which entails the development of forage production. The development of feed production is possible by improving the quality of products and reducing the cost of feed production. The quality can be improved by using the extrusion method, which increases the digestibility and nutritional value of feed. The addition of sapropel provides animals with vitamins and minerals. As a result of the scientific and economic experiments conducted on broiler chickens, it was found that birds that were fed with extruded sapropele grain had a greater weight gain. For the production of extruded sapropelic feed, an extruder with a double-entry screw and conical compression rings can be used. It can reduce extrusion losses and the screw length. To determine the design parameters, it is necessary to develop a mathematical model of the pressure change in the extruder along the screw length. Having analyzed the mixture movement through the annular conical channel of the die and built an equilibrium equation for the elementary section, we have a mathematical model for determining the pressure in front of the forming head. In a similar way, a mathematical model was built to determine the pressing pressure in front of the compression seal. The paper describes mathematical relationships for determining the pressure at any point in the extruder. Using the mathematical relationships, design parameters that affect the pressure in the extruder have been determined.

CFD Optimization of the Pre-Chamber Geometry for a Gasoline Spark Ignition Engine

In the present paper, an efficient optimization method based on Bayesian updating strategy is developed for the design of a spark-ignition engine equipped with pre-chamber. 3D computational fluid dynamics (CFD) simulation coupled with strategies including design of experiment, genetic algorithm, and machine learning methods is used to optimize the pre-chamber with desired combustion phasing. The optimization process starts from a design of experiment matrix of 11 design parameters, which are used to analytically characterize the pre-chamber geometry and set up the 3D combustion CFD. Taking CA50 as the single objective, the CFD results are then used to train the machine learning models. Different machine learning models are evaluated based on their Root Mean Square Error. Five machine learning models from five different categories are selected for second round evaluation. The trained machine learning model is used in the genetic algorithm optimization, which yields the optimized configuration and is again justified by CFD. The new CFD results based on the optimized design are added into the database to further refine the machine learning model. After 24 iterations for each selected machine learning models, the medium Gaussian support vector machine model is identified as the best method for the present application. Iterations using the medium Gaussian support vector machine model continue until a satisfactory result is achieved. Detailed combustion analysis is conducted to investigate the physical mechanism about how the design of pre-chamber influences the engine's performance. It is found that larger volume of the upper part of the pre-chamber results in stronger jet flow and turbulent intensity which further accelerates the flame propagation inside the pre-chamber, dominating the contrary effects from reduced pressure and temperature. Regression analysis shows that the radius of the pre-chamber is the most influential design parameter. The current work not only sheds light on the optimization of engine design, but also has demonstrated a general strategy applicable to the purpose of arbitrary engine optimization and mechanical system design.

INVESTIGATION OF DESIGN PARAMETERS FACADE FIRE-FIGHTING EAVES FOR PREVENT THE SPREAD OF FIRES ON FACADE STRUCTURES OF HIGH-RISE BUILDINGS

Purpose. The research based on FDS modeling aims to identify design parameters influence of the façade firefighting eaves at fire compartment border on the prevention of fire spreading in high-rise buildings.Methods. To calculate the temperature in high-rise building model Pyrosim computer system is used which serves as the user's shell application Fire Dynamics Simulator (FDS). This FDS system uses numerical algorithms to solve the complete Navier-Stokes differential equation system to determine the temperature and other hazardous factors during a fire.Results. This article deals with the results of using the FDS modeling to substantiate fire-fighting eaves design parameters, which are extended beyond the facade and are located at fire compartment border along the perimeter of high-rise buildings with a conventional height of more than 73.5 m. A comparative analysis of eaves' design parameters and their effect on the temperature distribution along the building facade during a possible fire was conducted. Comparative dependences of tempera-ture distribution on building facades were constructed, as well as their heating areas were determined.Scientific novelty. According to national and foreign regulations requirement analytical research and information sources on the of high-rise buildings design, fire safety requirements to the high-rise public buildings facades with a conventional height of more than 73.5 m were scientifically substantiated in terms of the requirements formation for limiting the fire spreading, smoke and building facades exterior constructions heating.Practical value. Obtained data was analyzed as a result of FDS modeling under the same reference conditions to provide a conclusion on facade fire-fighting eaves design parameters effectiveness at fire compartment border and further improvement ways of their construction and fire spread prevention in high-rise buildings.

Influence of Design Parameters of Idler Bearing Units on the Energy Consumption of a Belt Conveyor

This publication presents the results of laboratory tests of idler rolling resistance under operational loads. Operational loads are understood as radial and axial forces acting on the idler, with values corresponding to those that occur in the conditions of its operation in copper ore mines. Knowing the rolling resistance is important not only at the stage of conveyor design, selection of the drive power or calculations of the necessary belt strength, but also when improving and searching for new idler design solutions. The idlers adopted for this research were differentiated in terms of bearings and idler axial clearance. The investigations were carried out on a unique test stand designed and built by the authors. The construction of the stand enables simulating operational loads while measuring the rolling resistance. The test rig measures idler bearing losses and rolling drag, not belt indentation rolling resistance. The object of the research were ø133×465 idlers, which are most commonly used in the raw materials industry. The results show the possibility of reducing the belt conveyor energy consumption by appropriate selection of the design features of the idler bearing unit.

Research of the deformation of the shaping unit in an auger extruder caused by the extruding pressure in production of expanded clay

The technological process of forming expanded clay granules in an auger extruder is considered. Based on the analysis of well-known studies, considering the influence of conditions for shaping a ceramic mass on the quality of the produced porous aggregate, the following factor was identified: clogging of the shaping grid leads to an increase in pressure on it, its deformation and the impossibility of further operation. The authors note that there are practically no theoretical studies in the field of determining the most rational modes of functioning of the shaping equipment. The simulation model of an auger extruder shaping unit was developed in the Solid Works software environment, computational experiments on the influence of design parameters on shaping pressure were carried out, and recommendations for further technical application were formulated. The use of the results obtained will improve both the reliability of extruders with a perforated grid, as well as the quality of the final product with the specified quality parameters (bulk density and strength).

Effect of Alkali Reactions on the Rheology of One-Part 3D Printable Geopolymer Concrete

Yield strength development of 3D printable concrete by the early age activation reactions plays a vital role in the printability of geopolymer concrete. This study presents a rheo-chemical approach to investigate the early age strength development due to alkali reactions for the formulation of suitable 3D printable one-part geopolymer concrete. The influence of design parameters, including activator content, thixotropic additive (Magnesium Alumino Silicate -MAS), and retarder (sucrose) dosage, on the rheological properties of concrete were assessed. The shear stresses of geopolymer concrete were measured with the aid of a rotational rheometer for various shearing protocols that represent the major stages of printing operation (pumping, extrusion and building). The measured rheological properties were related to reaction kinetics of geopolymer mixes using FT-IR spectroscopy and calorimetry. The results revealed that, with MAS, activator and sucrose content of 0.75 wt%, 10 wt% and 1.5 wt% of the binder respectively, the formulated one-part geopolymer showcased enhanced printing properties. This is further demonstrated by printing laboratory-scale specimens and evaluating the hardened properties.

Analysis of airfoil pillars with impinging jets in a heat sink

In the current work, computational fluid dynamics investigation has been performed in case of air foil shaped pillars in heat sink with impingement of jet. The investigation has been made in terms of thermal and fluid attributes. Height diameter ratio is taken as design variable. The influence of design parameters has been focused on the response parameters like temperature, pressure, transfer of heat, convection coefficient, Nusselt number. The numerical model has been constructed to discuss the response parameters. The model has been validated with the available experimental and simulation results. With pillars, augmentation in height diameter proportion, almost 44% reduction in the temperature of the base has been noticed. Also 24% augmentation has been deduced in the convection coefficient, with an increase in the design parameter. Advancement in height diameter proportion leaded to 16% improvement in the Nusselt number.

Research on the influence of design parameters on mechanical performance of net arch bridge

In order to study the suspender layout parameters and design parameters of the tied arch bridge with mesh suspenders under the action of vehicle load, the structure stress is more reasonable and meets the higher economy and aesthetics. Taking a 96m span reticulated tied arch bridge as the engineering background, the finite element model is established by using Midas/Civil 2019 program. The variation law of internal force and Suspender Force of the structure is calculated and analysed under the change of rise span ratio and suspender number parameters, and the relatively optimal value range of corresponding parameters is given. The results show that the rise span ratio should be 0.2-0.24; The number of Suspenders for one side arch rib should be 34-38; The relatively optimal range of the above parameters is discussed for reference.

Research on mechanical-hydraulic system simulation method for multi-control multiway valve

Based on the control principle and flow distribution characteristics of the electro-hydraulic proportional load-sensitive multiway valve in an excavator, a system simulation model is established in AMEsim. After proving the accuracy of this model by comparing simulation results with theoretical results for various flow distribution characteristics under saturated and unsaturated conditions, this model is used to study the effect of three-way valve preload on the multiway valve system to prove that the simulation method can evaluate the influence of design parameters on the multiway valve system and then guide the design of multiway valves.

Finite element analysis applied to the taper mechanism of excavator assembly alignment analysis and optimization

This study aimed to solve the problem of interference misalignment when assembling the attachments of an excavator. A mechanical structure for taper guiding mechanism model was designed to improve the original mechanism. Interference distance, taper angles of the guiding mechanism, taper lengths of the guiding mechanism, and impact times of knocks were selected as design parameters. The optimal configuration of singular quality characteristics such as von Mises stress, von Mises strain, load, and strain energy was discussed using the Taguchi methods and L9 orthogonal arrays. The design method for multi-objective optimization was combined with grey relational analysis and used to examine the integrated index of all design parameters. The influence levels and mathematical relations of design parameters and their interactions were analyzed with response surface methodology and variance analysis. The grey relational analysis for multi-objective optimization shows the optimal design conditions were an interference distance of 2 mm, the taper angles of the guiding mechanism being 50°, taper lengths of the guiding mechanism being 60 mm, and impact times of knocks being 0.03 s, resulting in von Mises stress of 10.32 MPa, von Mises strain of 0.05%, a load of 379.45 N, and strain energy of 0.1 mJ. Overall effectiveness increased 34.28% when the original design was changed to the optimal design. Concerning the influence of design parameters on overall effectiveness, the impact times of knocks and its quadratic interactions had the most significant contributions.

On energy-absorbing mechanisms and structural crashworthiness of laterally crushed thin-walled structures filled with aluminum foam and CFRP skeleton

In the present study, thin-walled tubes filled with aluminum foam and CFRP skeleton (FCFTs) are developed and manufactured based on a multiple material system. The structural crashworthiness of the proposed design is investigated under quasi-static lateral loading. Further, the aluminum tube, the foam-filled tube and the tubes filled with CFRP skeleton are also designed and tested to perform a comparative study. It is found that the FCFT-1 (the tube filled with foam and CFRP skeleton with square cells) exhibits superior SEA (specific energy absorption), which is almost five times that of the individual aluminum tube, and almost 10% higher than that of the foam-filled tube. However, FCFT-2 (the tube filled with foam and CFRP skeleton with triangular cells) provides relatively lower energy-absorbing capacity, as its aluminum tube generates several axial cracks during crushing process leading to low deformation level of the foams. Furthermore, crush simulations are conducted to better understand the energy-absorbing mechanisms of the FCFT-1. The numerical results demonstrate that the plastic deformation of the separated foams makes up the major part of the total energy absorption. Besides, the performance improvement of FCFT-1 can be partly attributed to the fact that the separated foams generate larger plastic deformation during crushing process. Apart from this, the increased interaction effects between the separated foams and the CFRP skeleton lead to a higher FE (frictional energy), which also makes a slight contribution to the performance improvement of FCFT-1. Finally, parametric studies are performed to explore the influences of design parameters on the crashworthiness characteristics of FCFT-1. It is indicated that the energy-absorbing capacity can be slightly improved by raising cell number, proportion of 45° layer or foam density. The present work is expected to provide some insights for researchers and engineers to design such structures for energy absorption applications.

Influence of Design Parameters on Fresh Properties of Self-Compacting Concrete with Recycled Aggregate-A Review.

This article presents an overview of the bibliographic picture of the design parameter’s influence on the mix proportion of self-compacting concrete with recycled aggregate. Design parameters like water-cement ratio, water to paste ratio, and percentage of superplasticizers are considered in this review. Standardization and recent research on the usage of recycled aggregates in self-compacting concrete (SCC) exploit its significance in the construction sector. The usage of recycled aggregate not only resolves the negative impacts on the environment but also prevents the usage of natural resources. Furthermore, it is necessary to understand the recycled aggregate property’s role in a mixed design and SCC properties. Design parameters are not only influenced by a mix design but also play a key role in SCC’s fresh properties. Hence, in this overview, properties of SCC ingredients, calculation of design parameters in mix design, the effect of design parameters on fresh concrete properties, and the evolution of fresh concrete properties are studied.

A novel strategy of enhancing sky radiative cooling by solar photovoltaic-thermoelectric cooler

According to the characteristics of photovoltaic power generation and radiative cooling, a novel strategy of PVRC-TE (incorporation of radiative cooling with solar photovoltaic-thermoelectric cooler) system that enhancing sky radiative cooling by solar photovoltaic-thermoelectric cooler was proposed. Photovoltaic cells convert part of the sun’s radiation into electricity, reducing the solar incidence and heat absorption, and enhancing diurnal radiant cooling. At the same time, PV cells drive TEC module to generate cooling energy. The system makes full use of the characteristics of PV cells and radiative cooling, promotes each other, and realize 24-h all day operation. A mathematical model is established, and its performance is analyzed and parameterized by the validated model. The influences of design parameters and the common environmental effects on the performance of system, such as ambient temperature, wind speed, relative humidity and sunshine hours are included in the study. Taking Hefei city as an example, the influence of different meteorological parameters on the system performance is discussed. The simulation results show that the area with drought and long sunshine time in middle latitude is more suitable for high performance system. In PVRC-TE system, the area of photovoltaic and radiant cooling has the best geometric ratio. When the ratio of photovoltaic and radiation cooling area is 1, the maximum cooling energy gain in a day of the system is 285.57 MJ/m2.

Vpliv parametrov dizajna toplotnega izmenjevalnika iz polipropilenskega votlega vlakna na njegovo toplotno učinkovitost

Vpliv parametrov dizajna toplotnega izmenjevalnika iz polipropilenskega votlega vlakna na njegovo toplotno učinkovitost