Influence Of Various Geometrical Factors Research Articles

Impact of Double-Suction Pump Eye Diameter Variation on Cavitation Phenomena

Cavitation phenomena in pumps are major determinants of the lifespan of both the impeller and the pump itself, causing significant vibration and noise, which are critical concerns for pump designers. This study focuses on the influence of various geometric factors of the impeller, including the shape of the blade leading edge, blade inlet angle, number and thickness of blades, surface roughness, wrap angle, impeller outlet width, inlet hub diameter, and tip clearance. The pump analyzed in this study, which exhibited issues of vibration and noise in actual industrial settings, was evaluated by varying only the shroud diameter based on Gulich’s theory, while keeping other parameters constant, to assess the effects on cavitation phenomena across five different impellers. Single-phase analysis was initially conducted to evaluate the performance of each pump model, with the reliability of the numerical analysis methods validated by comparison with experimental data. Furthermore, to analyze cavitation phenomena, a multiphase flow analysis was performed using the Rayleigh–Plesset model within a computational fluid dynamics framework. Quantitative analysis of cavitation occurrence, NPSH3% head-drop performance, and bubble volume was conducted. The results confirmed that the M1 model, featuring a shroud diameter of 560 mm, exhibited superior cavitation resistance. Variations in cavitation occurrence observed under three different flow conditions demonstrated a nonlinear trend, but overall, improvements were noted within a specific diameter range. This study offers valuable insights and data for pump design applicable in real-world industrial settings.

Study of the Influence of Geometric Parameters on the Destruction Possibility of Aluminium Alloys during Pressing in Equal-Channel Step Matrix

The paper analyzes the influence of various geometric factors on the destruction possibility of aluminum alloys during pressing in an equal-channel step matrix, which allows to obtain an ultrafine-grained structure. It is found that the angle of the junction of the matrix channels has a significant effect on the Cockroft-Latham damage criterion, in contrast to the length of the inclined channel of the matrix. The most optimal value of the joint angle is 135° - in this case, the metal is processed with a sufficiently high intensity at a low level of the fracture criterion. The length of the inclined channel of the matrix is recommended to use no more than 15 mm to reduce the level of damage.

Circumferential Rosette Design for Extended Depth Hole-Drilling Residual Stress Measurements

The radial design for strain gauge rosettes used for hole-drilling residual stress measurements was established over 50 years ago and has remained almost unchanged since then. The design was developed to promote strain sensitivity, but was made without regard for ability to identify interior stresses. Consequently, only near-surface residual stresses can be identified. The aim of this study is to investigate rosette geometric features that may be refined to enable a significant increase in ability to identify interior stresses without significant loss of strain sensitivity. A finite element analysis was undertaken to model the influence of various geometrical factors on the depth response of a strain gauge rosette. It was found that that circumferentially oriented strain gauges allow residual stress measurements to be made to twice the depth of traditional radial strain gauges, with only minor loss in strain sensitivity. A new circumferential strain gauge rosette design based on the presented analysis is proposed for use where extended depth measurements are desired.

Influence of tip geometry on the spatial resolution of tip enhanced Raman mapping**Project supported by the National Natural Science Foundation of China (Grant No. 11434017) and the National Basic Research Program of China (Grant No. 2013CB632704).

In 2013, a breakthrough experiment pushed the Raman mapping of molecules via the tip-enhanced Raman scattering (TERS) technique to a sub-nanometer spatial resolution, going into the single-molecule level. This surprising result was well explained by accounting for the critical role of elastic molecule Rayleigh scattering within a plasmonic nanogap in enhancing both the localization and the intensity level of the Raman scattering signal. In this paper, we theoretically explore the influence of various geometric factors of the TERS system on the spatial resolution of Raman mapping, such as the tip curvature radius, tip conical angle, tip–substrate distance, and tip–molecule vertical distance. This investigation can help to find out the most critical geometric factor influencing the spatial resolution of TERS and march along in the right direction for further improving the performance of the TERS system.

Bending intensity of teeth under the influence of a distributed load in different phases of Novikov gearing

This paper provides the results of simulating the stress state of Novikov gearing wheel teeth influenced by the load distributed over the contact area and made on the basis of the standard reference profile with two bending intensity concentrators. The simulation was carried out in the finite element environment ANSYS when solving the spatial contact problem. The dependence for determining the parameter that takes into account the longitudinal extent of the contact area and the influence of various geometrical factors is obtained. The graphs and tables presenting the results of studying the stress changes in the gearing are provided up to the face contact, which is necessary when studying the transmission work in conditions of multipair gearing.

Influence of various geometric factors on the iodine-131 uptake measurement for solitary thyroid nodules

The influence of various geometric factors on I uptake measurements for solitary thyroid nodule was systematically investigated to derive an approach, based on routinely performed ultrasound examinations, to correct for the effect of geometric variations. The influence of size, shape, and position of a thyroid nodule, neck-to-detector distance and neck curvature on the uptake value was analyzed with a three-dimensional model. Uptake measurements using a tissue-equivalent neck phantom were carried out to verify the calculated correction factors and also to check the influence of scatter. Sonograms of 92 patients with solitary nodules were analyzed to correct for geometric variations. The correction factors were independent of the size and shape of the nodule, and the activity distribution of the solitary nodules can be approximated by a point source. The correction factors were mainly determined by the nodular depth and by the accuracy of the neck-to-detector distance and were affected to a lesser extent by the lateral position of the nodule as well as the curvature of the neck. The effect of scatter can be neglected if the energy window largely excludes Compton scatter, as is the case in the I uptake measurement. The ultrasound-derived correction factors ranged from 0.85 to 1.25. The proposed approach is capable of correcting for the geometric variation for a solitary nodule and can be easily applied in routine clinics. The accuracy of absorbed dose in radioiodine therapy can be improved in particular for nodules located well beneath the neck surface.

Three-dimensional problems of strongly interacting arbitrarily located penny-shaped cracks

Three-dimensional elastic interactions of arbitrarily located and oriented penny-shaped cracks are considered, and solutions for the stress intensity factors (SIFs) are obtained for several crack geometries. The work is based on the method of analysis of many cracks problems developed by Kachanov [1]. Unlike most of the results available in literature, the obtained solutions remain accurate for closely spaced, strongly interacting cracks. The effects of stress “shielding” and “amplification” and the influence of various geometrical factors are examined. The simplest crack-microcrack interactions in three dimensions are considered. The approximations of “weak interactions” and of “widely spaced cracks” are discussed. The interactions that are weak in their impact on the effective elastic constants may be strong in their impact on SIFs; this indicates that no simple relation between the deterioration of elastic stiffness of a microcracking solid and its progression towards failure seems to exist.