scholarly journals The effect of deformation of flow part of elastomeric elements of self-acting valves on characteristics of low-speed long-stroke compressor stages

2021 ◽  
Vol 5 (4) ◽  
pp. 33-38
Author(s):  
I. S. Busarov ◽  
◽  
S. S. Busarov ◽  
V. L. Yusha ◽  
◽  
...  
Keyword(s):  
Experimental Studies ◽  
Flow Section ◽  
Variable Cross ◽  
Cross Sectional ◽  
Low Speed ◽  
Experimental Stand ◽  
Integral Characteristics ◽  
Flow Part ◽  
Long Stroke ◽  
Feed Coefficient

The results of the study of the influence of changes in the area of the flow section in the seat of selfacting valves with elastomeric elements on the characteristics of low-speed compressor stages are presented. A method of experimental research of low-speed compressor stages with the possibility of obtaining instantaneous parameters of the gas state in the working chamber of the stage and its integral characteristics and an experimental stand for its implementation have been developed. The results of comparative experimental studies have confirmed the effectiveness of the valve design with a variable cross-sectional area of the seat in comparison with known designs — an increase in the feed coefficient and isothermal indicator efficiency is at least 10...15%.

Analysis of Physical Processes in the Flow Parts of Gas Turbines with Different Blade Chords

2021 ◽  
pp. 40-53
Author(s):  
V.D. Molyakov ◽  
B.A. Kunikeev ◽  
N.I. Troitskiy
Keyword(s):  
Flow Structure ◽  
Gas Turbines ◽  
Relative Elongation ◽  
Experimental Studies ◽  
Flow Path ◽  
Rotor Blades ◽  
Turbine Stage ◽  
Physical Processes ◽  
Integral Characteristics ◽  
Flow Part

Theoretical and experimental studies of the current flowing in the lattices of the turbine stage impeller with a change in the elongation of its blades at constant constraining diameters of the flow part (constant blade lengths) are carried out. Four single-stage turbines with different chords of rotor blades and their relative elongations have been investigated. To explain the nature of the integral characteristics of the turbine stage with a change in the relative elongation of the rotor blades, detailed studies of the spatial flow structure in the gap between wheels and behind the impeller were carried out. The peculiarity of the operation of four impellers in the turbine stage is shown when the geometry of the channels changes along the height of the flow path - from active at the root to highly reactive at the periphery. A characteristic redistribution of the local values of the efficiency and losses along the height of the lattices associated with a change in the elongation of the rotor blades and the rotation of the lattices has been revealed. It was found that with a decrease in the elongation of the rotor blades, the zone with the minimum efficiency moves from the root sections to the peripheral ones with its simultaneous restructuring and an increase in the minimum efficiency in this zone. In this case, the integral values of the efficiency of impellers with different relative elongations of the blades remain the same and sufficiently high.

Experimental studies of deformed state of the working chamber cylindrical part of low-speed long-stroke oil-free piston units

2020 ◽  
Author(s):  
S. S. Busarov ◽  
I. P. Aistov ◽  
K. A. Vansovich ◽  
D. S. Titov ◽  
R. Yu. Goshlya ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Cylindrical Part ◽  
Free Piston ◽  
Working Chamber ◽  
Low Speed ◽  
Deformed State ◽  
Long Stroke

Analytical and Experimental Studies of a Mechanical Pulse Generator

1974 ◽  
Vol 96 (2) ◽  
pp. 459-470 ◽  
Author(s):  
F. B. Safford ◽  
S. F. Masri
Keyword(s):  
Cutting Tool ◽  
Pulse Generator ◽  
Low Cost ◽  
Experimental Studies ◽  
Time History ◽  
Field Tests ◽  
Variable Cross ◽  
Force Output ◽  
Cross Sectional ◽  
Mechanical Pulse

A simple, low-cost mechanical pulse generator has numerous applications in laboratory investigations and field tests of structures. Applications may include shock tests, transient load simulations, and impedance measurements. By drawing a metal bar or mandrel having a variable cross-sectional area through a cutting tool (or vice versa) with suitable motive power, a waveform directly related to the configuration of the profile of the bar may be developed. The force time history generated would be dependent in part upon the velocity of the cutting tool. Reaction at the attachment points of the device transmits a force output to the driven load or structure. Initial experiments with a laboratory device show considerable promise by generating forces and waveforms comparable to predictions.

scholarly journals SOME TECHNOLOGICAL PARAMETERS OF VIBRATION CENTRIFUGAL EQUIPMENT AS A FACTOR IN CONTROL OF CONCRETE PROPERTIES

2021 ◽  
Vol 6 (1) ◽  
pp. 8-19
Author(s):  
M. Nazhuev ◽  
P. Dzhamilova ◽  
F. Bataeva ◽  
Z. Bakaev ◽  
A. Kukaev ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Experimental Studies ◽  
Building Structures ◽  
Technological Parameters ◽  
Cross Sectional ◽  
Technological Factors ◽  
Integral Characteristics ◽  
The Cost ◽  
Concrete Elements ◽  
Centrifugal Equipment

An increase in the volume of construction requires innovations in technological, structural and design solutions for reinforced concrete elements. As a result of the centrifugation method, variatropic concretes with different cross-sectional characteristics and structures made from them. Therefore, at the stages of calculation and design of building structures of a variatropic structure, an unreasonably large supply of bearing capacity is usually laid, leading to an impressive rise in the cost of promising building structures. It is proposed to combine centrifugation with vibration to increase the density and ensure a more uniform distribution of the components of the concrete mixture over the wall thickness of an annular section product, in particular columns. Vibration will be ensured through the use of clamps, which are put on the shafts of the installation. Within the framework of the proposed experimental setup for creating vibrocentrifuged samples of annular cross-section with a variatropic structure and a method for their manufacture, the technological parameters of vibration are identified, which have the most significant effect on the characteristics of vibrocentrifuged concrete. In the experiments, the following technological factors varied: the height of the technological protrusions of the clamps and the vibration mode. The problem of assessing the influence of these factors on the integral characteristics of concrete is investigated. The results of experimental studies of the influence of the considered technological factors on the integral characteristics of vibrocentrifuged concrete are presented. The results obtained show the feasibility of continuing the study of rational technological parameters of vibrocentrifugation to improve the characteristics of concrete and regulate its variatropy, which will allow the proposed method to be patented in the future and to design an improved vibrocentrifuged column with more fully utilized reserves of the bearing capacity of building structures.

Diagnostics of metal samples using the results of experimental and theoretical study of positively charged microparticles formed upon sample destruction

2018 ◽  
Vol 84 (10) ◽  
pp. 23-28
Author(s):  
D. A. Golentsov ◽  
A. G. Gulin ◽  
Vladimir A. Likhter ◽  
K. E. Ulybyshev
Keyword(s):  
Experimental Data ◽  
Early Stage ◽  
Experimental Studies ◽  
Material Model ◽  
Total Charge ◽  
Cross Sectional ◽  
Practical Applications ◽  
Mechanical And Electrical Properties ◽  
Order Of Magnitude ◽  
Using Data

Destruction of bodies is accompanied by formation of both large and microscopic fragments. Numerous experiments on the rupture of different samples show that those fragments carry a positive electric charge. his phenomenon is of interest from the viewpoint of its potential application to contactless diagnostics of the early stage of destruction of the elements in various technical devices. However, the lack of understanding the nature of this phenomenon restricts the possibility of its practical applications. Experimental studies were carried out using an apparatus that allowed direct measurements of the total charge of the microparticles formed upon sample rupture and determination of their size and quantity. The results of rupture tests of duralumin and electrical steel showed that the size of microparticles is several tens of microns, the particle charge per particle is on the order of 10–14 C, and their amount can be estimated as the ratio of the cross-sectional area of the sample at the point of discontinuity to the square of the microparticle size. A model of charge formation on the microparticles is developed proceeding from the experimental data and current concept of the electron gas in metals. The model makes it possible to determine the charge of the microparticle using data on the particle size and mechanical and electrical properties of the material. Model estimates of the total charge of particles show order-of-magnitude agreement with the experimental data.

DETERMINATION OF THE FUNCTION OF THE ROD’S CROSS-SECTIONAL AREA USING VIBRATION EIGENFREQUENCIES

2020 ◽  
Vol 0 (4) ◽  
pp. 19-24
Author(s):  
I.M. UTYASHEV ◽  
◽  
A.A. AITBAEVA ◽  
A.A. YULMUKHAMETOV ◽  
◽  
...  
Keyword(s):  
Cross Sectional Area ◽  
Variable Cross ◽  
Sectional Area ◽  
Longitudinal Vibrations ◽  
Cross Sectional ◽  
Method Error ◽  
Various Boundary Conditions ◽  
Elastic Fixation ◽  
Crosssectional Area

The paper presents solutions to the direct and inverse problems on longitudinal vibrations of a rod with a variable cross-sectional area. The law of variation of the cross-sectional area is modeled as an exponential function of a polynomial of degree n . The method for reconstructing this function is based on representing the fundamental system of solutions of the direct problem in the form of a Maclaurin series in the variables x and λ. Examples of solutions for various section functions and various boundary conditions are given. It is shown that to recover n unknown coefficients of a polynomial, n eigenvalues are required, and the solution is dual. An unambiguous solution was obtained only for the case of elastic fixation at one of the rod’s ends. The numerical estimation of the method error was made using input data noise. It is shown that the error in finding the variable crosssectional area is less than 1% with the error in the eigenvalues of longitudinal vibrations not exceeding 0.0001.

Longitudinal oscillation of a rod with a variable cross section

2019 ◽  
Vol 14 (2) ◽  
pp. 138-141
Author(s):  
I.M. Utyashev
Keyword(s):  
Cross Section ◽  
Natural Frequencies ◽  
Liouville Problem ◽  
Variable Cross Section ◽  
Variable Cross ◽  
Longitudinal Vibrations ◽  
Cross Sectional ◽  
Independent Functions ◽  
The Cross ◽  
The Right

Variable cross-section rods are used in many parts and mechanisms. For example, conical rods are widely used in percussion mechanisms. The strength of such parts directly depends on the natural frequencies of longitudinal vibrations. The paper presents a method that allows numerically finding the natural frequencies of longitudinal vibrations of an elastic rod with a variable cross section. This method is based on representing the cross-sectional area as an exponential function of a polynomial of degree n. Based on this idea, it was possible to formulate the Sturm-Liouville problem with boundary conditions of the third kind. The linearly independent functions of the general solution have the form of a power series in the variables x and λ, as a result of which the order of the characteristic equation depends on the choice of the number of terms in the series. The presented approach differs from the works of other authors both in the formulation and in the solution method. In the work, a rod with a rigidly fixed left end is considered, fixing on the right end can be either free, or elastic or rigid. The first three natural frequencies for various cross-sectional profiles are given. From the analysis of the numerical results it follows that in a rigidly fixed rod with thinning in the middle part, the first natural frequency is noticeably higher than that of a conical rod. It is shown that with an increase in the rigidity of fixation at the right end, the natural frequencies increase for all cross section profiles. The results of the study can be used to solve inverse problems of restoring the cross-sectional profile from a finite set of natural frequencies.

Płyty kołowe Hencky’ego–Bolle’a spoczywające na podłożu sprężystym Własowa

2020 ◽  
Vol 29 (4) ◽  
pp. 444-453
Author(s):  
Mykola Nagirniak
Keyword(s):  
Differential Equation ◽  
Circular Plate ◽  
Significant Influence ◽  
Single Layer ◽  
Medium Thickness ◽  
Cross Sectional ◽  
Equation Solution ◽  
Integral Characteristics ◽  
Two Parameter ◽  
Plate Deflection

The work presents the equations of the theory of symmetrical plates, resting on one-way, single-layer, two-parameter Vlasov’s subsoil. Two cases of differential equation solution of the plate deflection of thin and medium thickness on the ground substrate were analyzed depending on the size of the integral characteristics UÖD and 6ÖD. The example of loading the circular plate with a Pk load evenly distributed over the edge was considered and shows dimensionless graphs of deflection, bending torques and transverse forces in the plate and in the ground subsoil. The effect of the Poisson’s coefficient of the plate on deflection values and cross-sectional forces was investigated. The Poisson’s number has been shown to have a significant influence on deflection values and bending torque, however shown negligible effect on transverse forces values.

scholarly journals Pain acceptance and its impact on function and symptoms in fibromyalgia

2020 ◽  
Vol 20 (4) ◽  
pp. 727-736 ◽  
Author(s):  
Synne Flatlandsmo Tangen ◽  
Anne-Sofie Helvik ◽  
Hilde Eide ◽  
Egil A. Fors
Keyword(s):  
Chronic Pain ◽  
Linear Regression ◽  
Burden Of Illness ◽  
Longitudinal Design ◽  
Fibromyalgia Impact Questionnaire ◽  
Experimental Studies ◽  
Outcome Variable ◽  
Unknown Etiology ◽  
Cross Sectional ◽  
Pain Acceptance

AbstractObjectivesFibromyalgia is a chronic widespread pain (CWP) syndrome of unknown etiology with substantial burden of illness and functional impairment. Pain acceptance has emerged as an interesting target of therapy in chronic pain populations, but few studies have yet been done on the effect of pain acceptance on patients with fibromyalgia. The aim of the present study was to examine the relationship between pain acceptance and its impact on function and symptoms in fibromyalgia with both a cross-sectional and longitudinal design.MethodsThree hundred and sixty five participants aged 22–70 with fibromyalgia were recruited from the Norwegian Fibromyalgia Association (NFA). They filled out a questionnaire containing the Fibromyalgia Impact Questionnaire (FIQ), measurement of function and symptoms, and Chronic Pain Acceptance Questionnaire (CPAQ), measurement of pain acceptance, in addition to sociodemographic and clinical variables such as degree of fibromyalgia, depression and pain duration (T1 measures). One year after, 87 of the participants filled out the FIQ and clinical measures once again (T2 measures). Unadjusted and adjusted linear regression analyses were performed both for cross-sectional measures at T1 and for longitudinal measures from T1 to T2, with FIQ score as the outcome variable and CPAQ score at T1 as one of the main independent variables.ResultsHigher CPAQ score was significantly associated with a lower FIQ score at T1, also when adjusting for age, education, work, depression and Fibromyalgianess Score (p<0.01). Lower FIQ score indicate less impact of fibromyalgia on functioning. In addition, two adjusted linear regression models found higher pain acceptance (CPAQ score) at T1 to be associated with lower negative impact of fibromyalgia on function and symptoms (FIQ score) at T2 (p<0.01).ConclusionsHigher pain acceptance is associated with better functional level and less symptoms in fibromyalgia, both cross-sectionally and when measurements are separated in time. Further research should include experimental studies with acceptance-based interventions for this patient group.

Sign in / Sign up

Export Citation Format

Share Document