scholarly journals EXPERIMENTAL RESEARCH ON THE DISTRIBUTION DYNAMIC PRESSURE OF THE CIRCULATION MOVEMENT OF THE WORKING ENVIRONMENT IN TOROIDAL MOBILE CONTAINERS

2019 ◽  
pp. 33-44 ◽  
Author(s):  
Leonid Yaroshenko
Keyword(s):  
Dynamic Pressure ◽  
Outer Cylinder ◽  
Practical Interest ◽  
Dynamic Effect ◽  
Absolute Magnitude ◽  
Working Environment ◽  
Working Surface ◽  
Working Medium ◽  
Electromechanical Drive ◽  
Bulk Medium

In the operation of vibrating process machines for machining parts with a bulk working medium in a vibrating container, individual particles of this medium carry out a chaotic movement, and the whole mass of the bulk medium performs a circulatory motion that has a dynamic effect on the surface of the workpiece in the form of the total impact of many micro-impact parts. However, the velocity of movement and the dynamic impact of the particles of the working medium are not the same in different zones of the container. The distribution of the dynamic pressure of the circulating motion of the working medium in the vibrating toroidal containers is of considerable practical interest in the development of the structures of such vibrating machines and the technological processes of their operation. The distribution of the dynamic pressure of the working environment during the intersection of the toroidal container of vibrating technological machines with electromechanical drive and vertical unbalance shaft is experimentally investigated, which allows us to determine the most advantageous locations of the work pieces during their vibration treatment based on the conditions of efficiency and processing quality as well as maximum utilization of the kinetic energy of the circulating traffic of working environment when using it for additional forced movement on work pieces. Circulating movement creates the greatest dynamic pressure in the lower zones of the container, and as the distance from the surface of the container increases - dynamic pressure gradually decreases. The magnitude and nature of the distribution of the dynamic pressure of the working environment are also influenced by the direction of its circulation. When pressed by circulating movement of the environment to the outer cylinder of the working surface, ie to the points of the surface of the container having a large amplitude of vertical oscillations, the zone with high dynamic pressure is greater than in the case pressing it the inner cylinder of the working surface of the topper, that is, to the surface points of the container that have a smaller amplitude of vertical oscillations, thus reducing the absolute magnitude of the pressure.

Study on the performance of gas foil journal bearings with bump-type shim foil

2020 ◽  
pp. 135065012096900
Author(s):  
Hongyang Hu ◽  
Ming Feng ◽  
Tianming Ren
Keyword(s):  
Dynamic Stability ◽  
Load Capacity ◽  
Practical Interest ◽  
Journal Bearings ◽  
Working Environment ◽  
Foil Thickness ◽  
The Novel ◽  
Improvement Potential ◽  
Stiffness Model ◽  
The Stability

The upscaling of turbomachinery using gas foil journal bearings (GFJBs) is limited because of their limited load capacity and dynamic stability. The improvement potential of shim foil inserted under the bump foil of such bearings is investigated in terms of better bearing performance. The arch height difference Δ hb between the shim foil and bump foil can be zero or not to attain the different effect. By considering the local hardening structural stiffness and an Initial installation clearance due to the shim foil, the static and dynamic characteristics of the novel bearing were calculated through the finite difference method (FDM) and perturbation method, respectively. In the analysis, a modified bump stiffness model considering the variable foil thickness was established, and a 2 D thick plate model was adopted for the top foil. The characteristics of novel GFJB with and without preload were compared with the traditional bearing. The results indicate that the load capacity and direct stiffness of the novel GFJB with shim foil can be increased largely, especially when there is a preload (Δ hb≠0). And the improvement is reinforced as the increment of Δ hb. Moreover, the stability threshold speed ( STS) of rotor supported by the novel GFJBs is enhanced by the preload, which means better stability. In addition, an air compressor test has also been conducted to verify the improved supporting performance of novel bearings. Based on this study it is convinced that the addition of shim foil under a GFJB's bump foil can be of practical interest in the quest of enhanced load capacity and dynamic stability. Moreover, the installation of shim foil is not affected by the working environment and could even be retrofited on the existing GFJBs.

Fluid Kinetic Energy Based Limits in the Design of Control Valves and Valve-Related Systems

2007 ◽  
Author(s):  
Sanjay V. Sherikar ◽  
Vinay Nagpal
Keyword(s):  
Kinetic Energy ◽  
Dynamic Pressure ◽  
Practical Interest ◽  
Energy Criterion ◽  
Engineering Practice ◽  
Solid Particle Erosion ◽  
Control Valves ◽  
Reliable Performance ◽  
Flowing Stream ◽  
Vibration Noise

The term 1/2ρV2 represents kinetic energy per unit volume; it is also known as dynamic pressure, or velocity head, in flowing fluids and has units of pressure. It is one of the primary parameters in many wide-ranging phenomenon of practical interest in control valves and valve-related systems. The phenomena of interest include vibration, noise, solid particle erosion, liquid impingement erosion, cavitation and more. The description of the extent of these phenomena through their physics, as relating to acceptability of the system performance, is closely tied to the magnitude of the kinetic energy of the flowing stream; this permits use of this parameter as a criterion for reliable performance of control valves and valve-related systems. Kinetic energy criterion is a more general approach, when compared to the older engineering practice of specifying velocity limits only, because it takes into account the effect of fluid density which can be different by orders of magnitude depending on the process. The robustness of this criterion is confirmed by the results of its application in solving valve problems. Its main advantages are simplicity while staying close to the phenomena of interest.

EXPERIMENTAL STUDY OF THE CONDITIONS OF SPRAYING LIQUIDS WITH THE AIR FLOW

2021 ◽  
pp. 32-37
Author(s):  
NATALYA G. KOZHEVNIKOVA ◽  
Keyword(s):  
Dynamic Pressure ◽  
Practical Interest ◽  
Effective Area ◽  
Measurement Point ◽  
Factors Affecting ◽  
Pests And Diseases ◽  
Advantages And Disadvantages ◽  
Dynamic Pressure Measurement ◽  
Additional Resistance ◽  
Great Practical Interest

The processes of air movement in various types of air ducts are of great practical interest in terms of designing, manufacturing, and installing spraying devices used in agricultural production to create artificial fog with fi ne sprinkling and treat crops from pests and diseases. The authors analyze the existing methods of liquid spraying and reveal their main advantages and disadvantages. Under special attention is the pneumatic method. The study found that this method is used to spray contaminated liquids and the spray quality insignificantly depends on the liquid flow rate. It was revealed that one of the main factors affecting the quality indicators of spraying devices is the dynamic pressure of the gas medium acting on the liquid during its spraying. The research has determined that the dynamic pressure value of the airflow during the liquid movement in a horizontal duct depends on three factors: the presence of additional resistance, estimated by the value of the effective area duct, the position of the point at which the pressure was measured relative to the duct axis and the distance between the measurement point and the airflow source. The experimental data were tested for reproducibility using the Cochran criterion at the 5% signifi cancelevel, which proved the process reproducibility. The research has shown that the presence of additional resistance in the duct and the position of the dynamic pressure measurement point relative to the axis of the duct have the same effect on its value. The dynamic pressure of the airflow is primarily dependent on the remoteness of the measurement point from its source.

Durability Surveillance of Advanced Gas Turbines: Performance and Mechanical Baseline Development for the GE Frame 7F

1993 ◽  
Author(s):  
Cyrus B. Meher-Homji ◽  
A. N. Lakshminarasimha ◽  
G. Mani ◽  
Clark V. Dohner ◽  
Igor Ondryas ◽  
...  
Keyword(s):  
Electric Power ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Dynamic Pressure ◽  
Pressure Sensors ◽  
Practical Interest ◽  
Advanced Technology ◽  
Surveillance Program ◽  
Inlet Temperature ◽  
Base Line

This paper describes the methodology and approach of baseline development as part of a comprehensive Durability Surveillance Study Program of an Advanced Gas Turbine (AGT) sponsored by the Electric Power Research Institute (EPRI) on a GE Frame 7F gas turbine operating in peaking service. The gas turbine is an advanced technology 156 MW (ISO), 955 lb/sec machine operating at a turbine inlet temperature of 2300° F (rotor inlet temperature) and a pressure ratio of 13.5:1. The turbine is located at Potomac Electric Power Company (PEPCO) Station H plant in Dickerson, Maryland. In order to facilitate the durability surveillance, the turbine has a data acquisition and analysis system which obtains data from the control system (via serial port) as well as from special sensors such as proximity probes, dynamic pressure sensors, strain gauges and hot section pyrometers. With the GE Frame 7F and FA machines becoming very popular in utility applications worldwide, the EPRI Durability Surveillance Program and baseline generation methodology will be of considerable practical interest to gas turbine users. The basic methodology presented for baseline development can be used for any single shaft gas turbine. We believe the base-line to be of considerable importance in evaluating future condition of the machine as well as for maintenance planning. The paper also briefly describes the status and future plans of the EPRI durability surveillance program.

Entry flow in a curved pipe

1974 ◽  
Vol 65 (3) ◽  
pp. 517-539 ◽  
Author(s):  
M. P. Singh
Keyword(s):  
Secondary Flow ◽  
Dynamic Pressure ◽  
Steady Motion ◽  
Practical Interest ◽  
Initial Development ◽  
Curved Pipe ◽  
Curved Tube ◽  
Entry Condition ◽  
Pulsatile Flows ◽  
Inlet Conditions

This paper deals with the development of the flow in a curved tube near the inlet. The solution is obtained by the method of matched asymptotic expansions. Two inlet conditions are considered: (i) the condition of constant dynamic pressure at the entrance, which may be of practical interest in applications to blood flow in the aorta; and (ii) a uniform entry condition. It is shown that the geometry and the nature of the entry condition appreciably influence the initial development of the flow. The effect of the secondary flow due to the curvature on the wall shear is discussed and it is shown that the cross-over between shear maxima on the inside and the outside of the tube occurs at a downstream distance which is 1·9 times the radius of the tube for entry condition (i) while in the case of entry condition (ii) it is 0·95 times the radius, which is half the distance required in case (i). It is found that the pressure distribution is not significantly influenced by the secondary flow during the initial development of the motion. The analysis, which is developed for steady motion, can be extended to pulsatile flows, which are of greater physiological interest.

scholarly journals A wind effect of neutron component of cosmic rays at Antarctic station “Mirny”

2016 ◽  
Vol 2 (1) ◽  
pp. 71-75
Author(s):  
Павел Кобелев ◽  
Pavel Kobelev ◽  
Артем Абунин ◽  
Artem Abunin ◽  
Мария Абунина ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
High Latitude ◽  
Dynamic Pressure ◽  
Dynamic Effect ◽  
Wind Effect ◽  
High Mountain ◽  
Hourly Data ◽  
Neutron Component ◽  
Continue Monitoring ◽  
Barometric Coefficient

Estimation of barometric coefficient for neutron component of cosmic rays was performed for Antarctic station Mirny taking into account effect of dynamic pressure caused by wind in the atmosphere. Hourly data of continue monitoring of neutron component and data of the local meteo station have been used for the period 2007-2014. Wind velocity at the observatory Mirny reaches 20-40 m/s in winter that corresponds to dynamic pressure of 5-6 mb and leads to the error of 5% in variations of neutron component because of dynamic effect in the atmosphere. The results are interesting for high latitude and high mountain detectors, where affect Bernulli may be significant.

scholarly journals Study on Mining Pressure Control of Deep Coal Seam——Based on Artificial Fault Technology

2021 ◽  
Author(s):  
Xiaoding Xu ◽  
Yubing Gao ◽  
Manchao He ◽  
Qiang Fu ◽  
Xingjian Wei
Keyword(s):  
Mechanical Model ◽  
Abutment Pressure ◽  
Dynamic Pressure ◽  
Horizontal Distance ◽  
Rock Blasting ◽  
Distribution Law ◽  
Pressure Relief ◽  
Working Surface ◽  
Mining Pressure ◽  
Cutting Point

Abstract Based on the pressure transfer principle and stress distribution characteristics around a fault, introducing artificial fault technology to control the propagation of abutment pressure, and a mechanical model of abutment pressure under the influence of artificial fault was established. This new mechanical model can well fit the distribution law of mining stress after roof cutting. The pressure transfer mechanism of prefabrication support of rock blasting was analyzed, and the transfer trend of pressure and the mining stress of rock top was determined. It is of great significance to guide the implementation of the pressure relief work at the top of the stope. The study shows that the total energy of the system is conserved, the integrity of rock layer is destroyed by blasting, and the deformation and damage of pressure relief zone absorb a large amount of energy. Thus, the accumulated strain energy of abutment pressure region is released, and the influencing range of abutment pressure is reduced. As the horizontal distance from the cutting surface is farther away from the working surface, the smaller the stress difference on both sides of the cutting top, the less obvious the blocking effect of mining pressure. When the cutting point is closer to the working surface, the higher the peak value of abutment pressure due to the superposition of peripheral stress concentration caused by the cutting and peak of abutment pressure caused by mining. Then, the numerical simulation analysis was carried out, the results show that the technology of forming artificial fault by cutting the top can cut off the influence range of the mining pressure. It can effectively control the deformation of dynamic pressure tunnl. Finally, a practice of rock blasting pressure relief engineering was carried out, and the influencing range of abutment pressure of working face before blasting pressure reduction was reduced by 1/3 compared with that before the pressure relief.

scholarly journals Forecasting the influence of vehicle columns with liquid cargoes on bearing systems in agriculture

2020 ◽  
Vol 175 ◽  
pp. 11001
Author(s):  
Sergey Gridnev ◽  
Alexey Budkovoy ◽  
Yuriy Skalko ◽  
Rinat Muchtarov
Keyword(s):  
Nonlinear Oscillations ◽  
Dynamic Pressure ◽  
Moving Load ◽  
Dynamic Effect ◽  
Oscillatory System ◽  
Driven Systems ◽  
Dynamic Coefficients ◽  
Numerical Studies ◽  
Tanker Truck ◽  
Expert Models

Studies have been performed to evaluate the dynamic effect of columns of the same type of agricultural tanker truck on the beam-bearing systems of transport structures during movement in braking mode. The design scheme of the general oscillatory system is selected, a mathematical and numerical model of its behavior is developed, an algorithm for joint nonlinear oscillations is constructed. On the basis of the developed expert models, a computer complex was created using the simulation package of dynamic and event-driven systems Simulink MATLAB systems. Using it, a series of computational experiments was carried out to simulate situations of passage of convoys of cars with different parameters and with different driving modes. Various parameters varied: the speed of the column, the distance between the cars, the speed at the time of the start of braking, the place where the first car began to brake, the amount of steady deceleration, the number of tank compartments, and the value of operational underfilling. Based on the analysis of the results of numerical studies, the features of the dynamic effect of vehicles convoys carrying liquid cargo on load-bearing systems from the standpoint of the emergence of excess dynamic pressure on transport facilities and the need for its consideration are shown. Cases of a dangerous combination of parameters and driving modes are highlighted, and the need to distinguish such columns in a special class of moving load is shown. A significant increase in the dynamic coefficients of deflections in comparison with solid loads is shown. The need for full-scale research in this area with the aim of introducing amendments to regulatory documents has been proved.

scholarly journals The Main Ways to Control the Efficiency of Vibration Abrasive Processing

2021 ◽  
Vol 2131 (5) ◽  
pp. 052021
Author(s):  
Anatoly Prokopets ◽  
Vitaly Shenstein ◽  
Tatiana Prokopets ◽  
Elena Melnikova
Keyword(s):  
Adaptive Control ◽  
Processing Time ◽  
Experimental Studies ◽  
Working Environment ◽  
Necessary Condition ◽  
Technological Operation ◽  
Working Chamber ◽  
Working Medium ◽  
Main Factors ◽  
The Stability

Abstract The paper considers the main factors affecting the stability of the technological operation of vibration abrasive processing. The main ways of increasing the efficiency of processing by controlling its stability are revealed. The scheme of adaptive control of the process of vi-broabrasive machining is proposed according to the criterion of stability of the volume of loading of the working chamber, as one of the main factors that determine the stability of the cutting ability of the working medium (tool). The work substantiates the relevance of increasing the efficiency of vibration processing, as one of the promising methods of finishing. As a criterion of efficiency, the processing time was taken to ensure the specified quality indicators of the processed parts. Taking into account the peculiarities of vibroabrasive processing, three options for determining the minimum required processing time are proposed. In order to identify ways to increase the efficiency of processing, the analysis of the structure of the technological system was carried out, the classification of its elements was made. Based on the results of the analysis, it was concluded that a necessary condition for increasing the efficiency of processing is to ensure the stability of the parameters of the technological operation. In this regard, the main factors influencing the stability of the technological operation of vibration abrasive processing using the Ishikawa diagram are highlighted. The paper also presents the results of experimental studies of the influence of the volume of loading the working chamber on the cutting ability of the tool (working environment). Based on the results of theoretical and experimental studies, the main ways of increasing the efficiency of processing, including by controlling its stability, have been determined. The scheme of adaptive control of the process of vibroabrasive processing according to the criterion of stability of the volume of loading of the working chamber, as one of the main factors determining the stability of the cutting ability of the working medium (tool), is proposed.

Ru(II) Complex Based Optical Oxygen Sensors

2010 ◽  
Vol 123-125 ◽  
pp. 767-770 ◽  
Author(s):  
Maria Milanova ◽  
Joana Zaharieva ◽  
Salzitsa Anastasova ◽  
Dimitar Todorovsky
Keyword(s):  
In Situ Polymerization ◽  
Short Review ◽  
Oxygen Sensors ◽  
Working Environment ◽  
Oxygen Determination ◽  
Sensor Performance ◽  
Preparation Conditions ◽  
Working Medium ◽  
The Matrix ◽  
Lake Waters

A short review of recent investigations of the authors on the Ru(II)-based optical oxygen sensors is presented focused on the influence of: (i) type of the supporting matrix (SiO2 or polymethylmetacrylate based), (ii) precursors used (tetraethoxysilane, ormosil-type alkoxosilanes, methylmetacrylate, polymethylmetacrylate), (iii) method applied for the matrix synthesis, (iv) method for films deposition (dip- and spin coating), (v) chromophore leaching as a result of storage of the films in potentially aggressive media (water, diluted acidic and basic solutions) and (vi) working environment nature on the: a) films morphology, b) the analytical characteristics of the sensing component (linearity of the Stern-Volmer dependence, sensitivity of the device, reproducibility of the results), c) admissible parameters (pH, temperature) of the working medium. Special attention is paid on the effect of sol-sonication (as a tool against dye microcrystallization). The results obtained permit optimal precursors, sol preparation conditions and coating procedure to be recommended for gas and for dissolved oxygen measurement, respectively. The sonication of the sol ensures a rather significant improvement of the sensor performance. The strong quenching of the chromophore in the case of in-situ polymerization of the methylmetacrylate is observed.The sensing films are successfully applied for oxygen determination in natural lake waters and beer.

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