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.

Byram Derivation of the Energy Criterion for Forest and Wildland Fires

1993 ◽  
Vol 3 (3) ◽  
pp. 131 ◽  
Author(s):  
RM Nelson
Keyword(s):  
Kinetic Energy ◽  
Thermal Energy ◽  
Wind Field ◽  
Vertical Structure ◽  
Energy Criterion ◽  
Current Interest ◽  
Wildland Fires ◽  
Dimensionless Ratio ◽  
Large Fires

G.M. Byram's energy criterion for forest and wildland fires consists of two equations: one for computing the rate of flow of kinetic energy in the atmosphere due to the wind field (Pw), and one for estimating the rate of conversion of thermal energy to kinetic energy in the convection column (Pf). The derivation of the equations has remained unpublished since their introduction in 1959. Byram considered the dimensionless ratio of Pf to Pw an indicator of the vertical structure of convection over a fire and referred to the ratio as the convection number, Nc. In view of past and current interest in the behavior of large fires, Byram's derivation of the equations for Pw and Pc is presented along with a sketch and some additional wording for purposes of clarification. The assumptions and possible limitations in Byram's analysis are discussed.

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.

Maximum amplitudes in transient resonance of distributed-parameter systems / Amplitudy maksymalne w rezonansie przejściowym układów o parametrach rozłożonych

2012 ◽  
Vol 57 (3) ◽  
pp. 657-665 ◽  
Author(s):  
Jerzy Michalczyk
Keyword(s):  
Energy Balance ◽  
Kinetic Energy ◽  
Continuous System ◽  
Distributed Parameter ◽  
Engineering Practice ◽  
Continuous Systems ◽  
Two Dimensional ◽  
Approximate Methods ◽  
Unbalanced Rotor ◽  
Transient Resonance

Abstract The application of the kinetic energy balance for the estimation maximum amplitudes of continuous systems in the transient resonance excited by the free coasting of unbalanced rotor or piston machines placed on the continuous system - was proposed in the study. The exact as well as the approximate methods were shown. For the typical one- and two-dimensional systems the calculation formulae, useful for the engineering practice, were given.

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 Experimental analysis and numerical modeling of particle embedment and fracture in the solid particle erosion of ductile materials

2021 ◽  
Author(s):  
Vahid Hadavi
Keyword(s):  
Numerical Modeling ◽  
Kinetic Energy ◽  
Solid Particle ◽  
Process Parameters ◽  
Three Dimensional ◽  
Pulsed Laser ◽  
Particle Orientation ◽  
Solid Particle Erosion ◽  
Particle Erosion ◽  
Particle Fracture

Embedment and fracture of abrasives are two often neglected important phenomena that can affect material removal occurring in industrial processes that involve high speed impact of particles on relatively ductile targets. This thesis proposes new methodologies to predict the likelihood of particle embedment and fracture for a typical solid particle erosion application. Double-pulsed laser shadowgraphy was used to measure the instantaneous orientation of angular 89-363 μm SiC particles within a micro-abrasive jet, in order to assess whether their orientation affected the propensity for particle embedment. A tendency for particles to orient with the jet axis was measured and successfully modelled (<9% error), with larger abrasives more likely to orient. The measured instantaneous orientation of particles was used to generate a three-dimensional coupled finite element and smoothed particle hydrodynamics model capable of simulating the particle embedment. Use of various combinations of process parameters yielded embedment predictions that agreed with measured ones with, at most, a 16% error. Increases in particle size, orientation angle, and velocity were found to enhance the propensity for embedment. Double-pulsed laser shadowgraphy was used to record the impact and fracture of abrasives upon impact. A numerical model that utilized an Element Free Galerkin (EFG) technique with a novel scheme for generating realistic three-dimensional particle geometries was used to simulate the particle fracture. For a wide variety of process parameters, the numerical predictions of particle average size, roundness and rebound velocity agreed with the corresponding measurements to within 10%, at most. The propensity for particle fracture was found to depend on the magnitude of particle kinetic energy perpendicular to the target. It was confirmed that at the same incident velocity, larger particles were more likely to fracture. However, for the same kinetic energy, smaller particles were more likely to fracture. To the best knowledge of the author, this thesis is the first to report measurements of particle orientation and particle fracture in abrasive jets, and the first to develop numerical modeling of particle fracture and embedment. The results have important implications for erosion testing and abrasive jet machining operations.

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.

scholarly journals Solid particle erosion of materials for use in gas pipeline control valves

2021 ◽  
Author(s):  
Ehsan Akbarzadeh
Keyword(s):  
Tungsten Carbide ◽  
Solid Particle ◽  
Hardened Layer ◽  
Impinging Jets ◽  
Solid Particle Erosion ◽  
Scanning Electron Micrographs ◽  
Particle Erosion ◽  
Control Valves ◽  
Erosion Rates ◽  
Scanning Electron

To aid in the materials selection of gas control valves, the solid particle erosion behaviour of twelve metals was investigated using impinging jets of magnetite particles. The erosion rates were measured for two different particle sizes, two different velocities, and six different impingement angles. Scanning electron micrography and EDX (Energy Dispersive X-ray analysis) mapping was used to investigate the erosion mechanisms and the extent of particle embedding. There was no measurable erosion for the Tungsten Carbide samples, even for very long exposure times. For nickel plated steel, the plating was found to delaminate, resulting in a brittle erosive response. For all other tested materials, the measured erosion rates and scanning electron micrographs indicated a ductile erosion mechanism under all conditions considered. The erosion rates were found to fit a semi-empirical erosion model due to Oka et al. [1] well. The most erosion resistant materials were found to be the Solid tungsten carbide (WC) and Solid Stellite 12 and the least erosion resistant materials were A1018 carbon steel nickel plated and A240 Type 410 stainless steel plate. With all other conditions being equal, a larger erosion rate was measured when utilizing the smaller particles, than when the large particles were used. This counter-intuitive result was demonstrated to be due to a combination of effects, including the formation of thicker hardened layer more embedded particles, and more particle fragmentation when utilizing the larger particles.

scholarly journals On the flexure of thin cylindrical shells and other "thin" sections

1927 ◽  
Vol 116 (773) ◽  
pp. 104-114 ◽  
Keyword(s):  
Practical Interest ◽  
Elastic Solid ◽  
Elastic Stability ◽  
Neutral Axis ◽  
The Body ◽  
Order Effects ◽  
Engineering Practice ◽  
Recent Experience ◽  
Thin Sections ◽  
The Moment

It is a generally appreciated deduction from St. Venant’s solution of the flexure problem that a beam in which the material is disposed at a distance from the neutral axis is superior to the solid section in economy of material. St. Yenant’s solution, however, suggests that this advantage increases without limit as the thickness of the material is reduced and the distance from the neutral axis is increased. It has, of course, been generally realised that this conclusion is not supported by ordinary engineering practice, and recent experience in the use of high tensile steels and problems of aircraft structure have emphasised the desirability of a further examination of the flexure problem. St. Venant’s solutions are obtained when the equations of equilibrium of an isotropic elastic solid are made linear by the neglect of terms of higher orders than the first: and by Kirchhoff’s theorem of determinancy these solutions may then be considered unique and stable. To attack problems of stability it is necessary, as is shown by R. V. Southwell in his ‘General Theory of Elastic Stability,’ to include some of the second order effects. It is, in fact, only when these become considerable that Kirchhoff’s theorem fails and instability becomes possible. By this general treatment various classes of instability are obtained or indicated, but the only ones susceptible to analysis or of practical interest (on account of the “elastic limit” which is a feature of all practical materials) are those in which at the moment of instability the strains are still small. Bryant has shown that this will only occur, as in the case of thin rods and shells, when one dimension of the body is small compared with others.

The Abrasive Flow Machining Simulation of Common Rail Tube Holes Based on FLUENT

2014 ◽  
Vol 687-691 ◽  
pp. 4376-4381 ◽  
Author(s):  
Li Feng Zhu ◽  
Kai Wang ◽  
Huan Wu ◽  
Dong Xiu ◽  
Li Zhong Sun
Keyword(s):  
Numerical Analysis ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Dynamic Pressure ◽  
Three Dimensional ◽  
Common Rail ◽  
Machining Process ◽  
Two Phase ◽  
Abrasive Flow Machining ◽  
Solid Liquid

Based on the solid - liquid two-coupling theory, Use abrasive medium viscosity-temperature characteristics related to the mathematical model, using solid - liquid two-phase solution method Mixture models and standards, turbulence model combining with common rail pipe hole as the research object, choose different initial temperatures and processing procedures, numerical analysis was carried out on the flow channel wall temperature and turbulent kinetic energy. Using numerical analysis software FLUENT Abrasive Flow Machining rail tube orifice structure was three-dimensional numerical analysis; obtain a steady-state pressure, dynamic pressure, velocity, turbulent kinetic energy image, to study Abrasive Flow Machining process provides a theoretical basis and technical support.

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