scholarly journals Frequency and Magnitude Analysis of the Macro-instability Related Component of the Tangential Force Affecting Radial Baffles in a Stirred Vessel

10.14311/360 ◽  
2002 ◽  
Vol 42 (3) ◽  
Author(s):  
P. Hasal ◽  
J. Kratěna ◽  
I. Fořt
Keyword(s):  
Experimental Data ◽  
Spectral Analysis ◽  
Tangential Force ◽  
Relative Magnitude ◽  
Axial Position ◽  
Total Force ◽  
Dimensionless Frequency ◽  
Liquid Viscosity ◽  
Measuring Point ◽  
Vessel Bottom

Experimental data obtained by measuring the tangential component of force affecting radial baffles in a flat-bottomed cylindrical mixing vessel stirred with pitched blade impellers is analysed. The maximum mean tangential force is detected at the vessel bottom. The mean force value increases somewhat with decreasing impeller off-bottom clearance and is noticeably affected by the number of impeller blades. Spectral analysis of the experimental data clearly demonstrated the presence of its macro-instability (MI) related low-frequency component embedded in the total force at all values of impeller Reynolds number. The dimensionless frequency of the occurrence of the MI force component is independent of stirring speed, position along the baffle, number of impeller blades and liquid viscosity. Its mean value is about 0.074. The relative magnitude (QMI) of the MI-related component of the total force is evaluated by a combination of proper orthogonal decomposition (POD) and spectral analysis. Relative magnitude QMI was analysed in dependence on the frequency of the impeller revolution, the axial position of the measuring point in the vessel, the number of impeller blades, the impeller off-bottom clearance, and liquid viscosity. Higher values of QMI are observed at higher impeller off-bottom clearance height and (generally) QMI decreases slightly with increasing impeller speed. The QMI value decreases in the direction from vessel bottom to liquid level. No evident difference was observed between 4 blade and 6 blade impellers. Liquid viscosity has only a marginal impact on the QMI value.

scholarly journals The Tangential Force Affecting the Radial Baffles in a Stirred Vessel: Analysis of the Macro-instability Related Component

10.14311/450 ◽  
2003 ◽  
Vol 43 (4) ◽  
Author(s):  
P. Hasal ◽  
I. Fořt ◽  
J. Kratěna
Keyword(s):  
Experimental Data ◽  
Spectral Analysis ◽  
Tangential Force ◽  
Low Frequency ◽  
Frequency Component ◽  
Relative Magnitude ◽  
Tangential Component ◽  
Vertical Position ◽  
Total Force ◽  
Rushton Turbine

Experimental data obtained by measuring the tangential component of the force affecting radial baffles in a flat-bottomed cylindrical mixing vessel stirred with a Rushton turbine impeller is analysed. Spectral analysis of the experimental data demonstrated the presence of its macro-instability (MI) related low-frequency component embedded in the total force. Two distinct dimensionless frequencies (both directly proportional to the impeller speed of rotation N) of the occurence of the MI component were detected: a lower frequency of approximately 0.025N and a higher frequency of about 0.085N. The relative magnitude QMI of the MI-related component of the total tangential force was evaluated by a combination of proper orthogonal decomposition (POD) and spectral analysis. The values of magnitude QMI varied in the interval [rom approximately 0.05 to 0.30. The magnitude QMI takes maximum values at low Reynolds number values (in laminar and transitional regions). In the turbulent region (ReM >20000) the QMI value is low and practically constant. The dependence oj the QMI values on vertical position in the vessel is only marginal. The results suggest that the magnitude of the MI component of the force is significantly influenced by the liquid viscosity and density.

scholarly journals Dynamics of the Blade Channel of an Inducer Under Cavitation-Induced Instabilities

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Angelo Pasini ◽  
Ruzbeh Hadavandi ◽  
Dario Valentini ◽  
Giovanni Pace ◽  
Luca d'Agostino
Keyword(s):  
Experimental Data ◽  
Spectral Analysis ◽  
Main Flow ◽  
Operating Conditions ◽  
Flow Instabilities ◽  
Mean Flow ◽  
Flow Oscillations ◽  
Rotating Frames ◽  
The Mean ◽  
High Head

A high-head three-bladed inducer has been equipped with pressure taps on the hub along the blade channels with the aim of more closely investigating the dynamics of cavitation-induced instabilities developing in the impeller flow. Spectral analysis of the pressure signals obtained from two sets of transducers mounted both in the stationary and rotating frames has allowed to characterize the nature, intensity, and interactions of the main flow instabilities detected in the experiments: subsynchronous rotating cavitation (RC), cavitation surge (CS), and a high-order axial surge oscillation. A dynamic model of the unsteady flow in the blade channels has been developed based on experimental data and on suitable descriptions of the mean flow and the oscillations of the cavitating volume. The model has been used for estimating at the inducer operating conditions of interest the intensity of the flow oscillations associated with the occurrence of the CS mode generated by RC in the inducer inlet.

scholarly journals Double-well trap for charged microparticles

2021 ◽  
Vol 2103 (1) ◽  
pp. 012222
Author(s):  
Olga Kokorina ◽  
Vadim Rybin ◽  
Semyon Rudyi
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Strong Correlation ◽  
Paul Trap ◽  
Axial Position ◽  
Experimental Setup ◽  
Mass Ratio ◽  
Linear Paul Trap ◽  
Spatial Selection ◽  
Axial Density

Abstract We propose a double-well linear Paul trap for particle’s spatial selection according to the charge-to-mass ratio. To perform spatial selection we implemented an experimental setup that permits to detect particles’ positions in the double-well trap from three different view-points: top, front left, and front right. The setup gives an opportunity to monitor the particles’ axial density distribution in real-time. We have shown a strong correlation between axial position of separated localization areas and the DC voltages applied to the rod and end-cap electrodes. We have experimentally determined the critical localization parameters where double-well mode acquires for all the trapped charged microparticles. According to the experimental data and a numerical simulation a upper value of charge-to-mass ratio of the trapped microparticles was estimated.

Limits on variances from symmetry in neutral kaon decays

1972 ◽  
Vol 330 (1582) ◽  
pp. 331-347 ◽  
Keyword(s):  
Experimental Data ◽  
Relative Magnitude ◽  
Neutral Kaon ◽  
Leptonic Decay ◽  
Kaon Decays ◽  
Conservative View ◽  
Better Than

An analysis is made o f the limits on the possible departures from CP -, T -, and TCP -invariance, both in the structure of K L and K S states and in the decay amplitudes to xx and xIv channels. A small violation of the requirements of CP - and T -invariance on the structure of K L and K S states can be deduced under quite plausible assumptions, but there is no evidence of any other departure from the requirements of CP -, or T -, or TCP -in variance. However, the present limit for one measure 8 of TCP -noninvariance is several times larger than the estim ated value of the corresponding CP - and T -noninvariance parameter or = Re<K L |K S >. Taking a conservative view of the experimental data, symmetry-violating parts of decay amplitudes are lim ited to better than 1 % for the I = 0 channel and to within a small percentage for the I = 2 channel, in relative magnitude. The corresponding limits which can be deduced for leptonic decay amplitudes are som ewhat larger but there are indications that symmetry-violating amplitudes are unlikely to exceed a small percentage in relative magnitude.

On the Mechanics of Shear Spinning

1961 ◽  
Vol 83 (2) ◽  
pp. 125-130 ◽  
Author(s):  
Serope Kalpakcioglu
Keyword(s):  
Experimental Data ◽  
Shear Strain ◽  
Specific Energy ◽  
Tangential Force ◽  
Metal Flow ◽  
Shear Strain Rate ◽  
Analytical Work ◽  
Spinning Process ◽  
Shearing Mechanism ◽  
Shear Spinning

With the use of an idealized model of the shear spinning process some of the basic quantities in the shearing mechanism have been defined and formulated, these being: shear strain, shear strain rate, specific energy, and tangential force (torque) in spinning. An experimental technique to study metal flow in shear spinning has been described. The results of analytical work have been compared with experimental data.

scholarly journals Development and Identification of Working Parameters for a Lychee Peeling Machine Combining Rollers and a Pressing Belt

2019 ◽  
Vol 1 (4) ◽  
pp. 550-566 ◽  
Author(s):  
Le ◽  
Nguyen ◽  
Pham ◽  
Ly ◽  
Le ◽  
...  
Keyword(s):  
Experimental Data ◽  
Rotation Speed ◽  
Tangential Force ◽  
Static Friction ◽  
Gap Size ◽  
Operational Parameters ◽  
Length Width ◽  
Working Principle ◽  
Post Harvesting ◽  
Working Parameters

This work describes the development, design, and parameter identification of a lychee peeling machine. The working principle of the machine combines two rollers with a pressing belt to separate the peel from the fruits. It was designed and its operational parameters identified on the basis of experimental data on the Thieu lychee, which currently covers about 80% of the plantation area in Vietnam. To this end, the first step was to measure the physical characteristics of the fruits, such as size, shape, and density. Moreover, the coefficient of static friction between lychees and rubber rollers, and the critical peeling force, were identified, with a view to optimizing the operational parameters later on. Results showed that a minimum tangential force of 10.5 N is needed to break the peel and separate it from the pulp. Based on the balanced force principle, various optimal machine parameters such as roller rotation speed, roller diameter, roller length, gap size between the two rollers, belt velocity, and minimum pressure of the belt were calibrated. In addition, spiral grooves were created on the roller surface to facilitate the motion of the fruits. The optimal results were roller size 900 × 100 mm (length × diameter), rotation speed 159 RPM, gap size between rollers 4 mm, belt size 850 × 60 mm (length × width), belt pressure 13.5 N, and belt velocity 140 mm/s. Using the design and operational parameters mentioned above, the machine was able to perform regularly at a throughput of 100 kg/h, as demanded by the current market. Moreover, it would be easily feasible to combine multiple pairs of rollers and pressing belts in order to increase throughput. The methodology for the design of this peeling machine and identification of working parameters with respect to experimental data could be applied in many other post-harvesting configurations.

Computational and experimental study of the stress state of the connecting rod of the opposed compressor to assess the probability of failure-free operation

2020 ◽  
Vol 86 (5) ◽  
pp. 52-58
Author(s):  
I. M. Petrova ◽  
M. A. Filimonov
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Stress State ◽  
Numerical Experiment ◽  
Field Experiments ◽  
Fatigue Cracks ◽  
Tangential Force ◽  
Experimental Studies ◽  
Connecting Rod ◽  
Comparison Of The Results

Fatigue cracks in the piston heads of the connecting rods of opposed compressors can occasionally develop in service. A study of the loading of the connecting rods of the compressors operating in chemical production was carried out to assess the probability of their failure-free operation. Since the experimental study of stresses acting in large structural elements is rather difficult, the study of the stress state was carried out using computational methods with subsequent comparison of the results with the experimental data. When loading the connecting rod, there is an area affected by the distributed load and another area with a gap between the cylindrical surfaces where the contact pressure is absent. The forces acting on the boundary of the contact areas and the gap of the finger with the connecting rod bore are determined: the radial force N, tangential force Q and bending moment M. N and Q are considered functions of the contact angle α. Using numerical experiments, we determined the stresses in the zone from the angle α corresponding to the end of the contact zone to the angle of transition of the head in the shank of connecting rod in conditions of varied operational loads and gaps in the connecting rod — finger coupling. The values and character of changes in the loads affecting the crank mechanism of the compressor during operation are determined experimentally. The distribution of stresses in the sections of the connecting rod and the most loaded cross-sections are specified. the results of the numerical experiment are compared with the experimental data. Comparison of the results of numerical and field experiments has shown that the numerical experiment provides the similar assessment of the stress distribution, moreover, the numerical experiment allows us to estimate the simultaneous effect of both loads and gaps on the stress growth which is almost impossible to be determined by experimental studies.

Effects of a Change of Poisson’s Ratio Analyzed by Twinned Gradients: Illustrated by Simple Solutions of Boussinesq’s Problem of a Normal Force and Cerruti’s Problem of a Tangential Force Acting on the Surface of a Large Solid, and by a Simple Derivation of the Stresses in a Rotating Thick Disk

1940 ◽  
Vol 7 (3) ◽  
pp. A113-A116
Author(s):  
H. M. Westergaard
Keyword(s):  
Poisson’S Ratio ◽  
Normal Force ◽  
Plane Surface ◽  
Tangential Force ◽  
Thick Disk ◽  
Poisson's Ratio ◽  
Total Force ◽  
Principal Stresses ◽  
Simple Derivation ◽  
Boussinesq’S Problem

Abstract Some problems of elasticity have a simple solution for a particular value of Poisson’s ratio. For example, Boussinesq’s problem of a normal force and Cerruti’s problem of a tangential force, acting on the plane surface of a semi-infinite solid, are solved when Poisson’s ratio is 1/2 by referring to Kelvin’s problem of a force at a point in the interior of an infinite solid. For, when Poisson’s ratio is 1/2, the solution of Kelvin’s problem can be stated in terms of one principal stress at each point, acting along the radial line from the point of the load; the other principal stresses are zero; and one half of the total force may be assigned to one half of the infinite solid. For other values of Poisson’s ratio terms must be added in the formulas for the displacements and stresses. The derivations that have been available are somewhat lengthy, especially for Cerruti’s problem. The difficulties are reduced by a simple analytical device, here called “the twinned gradient.” The displacement to be added by the change of Poisson’s ratio is stated as the gradient of a potential except that one of the components is replaced by its twin, an identical component in reversed direction. This device also lends itself to a simplification of the analysis of stresses in a rotating thick disk.

scholarly journals A model for the effect of bulk liquid viscosity on cavitation bubble dynamics

2017 ◽  
Vol 19 (31) ◽  
pp. 20635-20640 ◽  
Author(s):  
Yang Shen ◽  
Kyuichi Yasui ◽  
Tong Zhu ◽  
Muthupandian Ashokkumar
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Cavitation Bubble ◽  
Bubble Dynamics ◽  
Single Bubble ◽  
Bulk Liquid ◽  
Liquid Viscosity ◽  
Single Bubble Dynamics ◽  
Theoretical Results

The effect of bulk liquid viscosity on single bubble dynamics has been investigated using numerical simulations. The theoretical results obtained are supported by the published experimental data.

scholarly journals Characteristics of secondary droplets produced by the impact of drops onto a smooth surface

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Haixiang Zhang ◽  
Ye Gao ◽  
Xiwen Zhang ◽  
Xian Yi ◽  
Yanxia Du ◽  
...  
Keyword(s):  
Experimental Data ◽  
Size Distribution ◽  
Smooth Surface ◽  
Average Diameter ◽  
High Impact ◽  
Solid Surfaces ◽  
Liquid Viscosity ◽  
High Impact Velocity ◽  
Secondary Droplets ◽  
The Impact

AbstractThis work investigates the splashing behaviors of droplets impacting on solid surfaces and mainly focuses on the characteristics of secondary droplets. According to the experimental results, two different splashing patterns, corona splash and levitating-lamella breakup, are observed. A new breakup mode, named rim-segmenting, is found during the levitating-lamella breakup. In particular, the detailed information of the splashing secondary droplets, including the size, velocity, angle, and total volume of the splashing secondary droplets is obtained from the experimental data. The size distribution of the splashing secondary droplets obeys the gamma distribution function. The average diameter and splashing angle of the secondary droplets are mainly related to the Reynolds number Re, and can be expressed as functions of Re. High impact velocity and liquid viscosity will result in a wider size distribution range of splashing secondary droplets. We also put forward an empirical model to predict the total splashing volume, which is consistent with the experimental data both in this work and previous studies. This work is believed to provide insights on the prediction of the characteristics of splashing secondary droplets.

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