Numerical Study of Modular 5.56 mm Standard Assault Rifle Referring to Dynamic Characteristics

2015 ◽  
Vol 65 (6) ◽  
pp. 431 ◽  
Author(s):  
P. Płatek ◽  
K. Damaziak ◽  
J. Małachowski ◽  
P. Kupidura ◽  
R. Woźniak ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Multibody System ◽  
Numerical Study ◽  
Experimental Tests ◽  
Numerical Approach ◽  
Complex Character ◽  
Strength Parameters ◽  
Numerical Studies ◽  
Modelling Methodology ◽  
Good Agreement

<p>The paper describes investigations carried out to verify a loading mechanism of a newly designed modular assault rifle MSBS-5.56. A complex character of interaction between its elements during a reloading process encouraged the authors implement a numerical approach based on the multibody system to specify the essential dynamic characteristics. The achieved results were compared to the data recorded during the experimental tests on the shooting range. Owing to the proposed modelling methodology, a good agreement between experimental and numerical studies has been achieved.<br />A numerical model presented in the paper will be applied in further investigations to analyse strength parameters of the reloading mechanism and to conduct additional optimisation studies.</p>

A Combined Experimental and Numerical Study of Flow Past a Single Step Cylinder

2010 ◽  
Author(s):  
Chris R. Morton ◽  
Serhiy Yarusevych
Keyword(s):  
Vortex Shedding ◽  
Numerical Study ◽  
Experimental Tests ◽  
Numerical Approach ◽  
Single Step ◽  
Wake Flow ◽  
Cylinder Wake ◽  
Flow Topology ◽  
Single Vortex ◽  
Flow Past

The current study investigates flow past a step cylinder for ReD = 1050 and D/d = 2 using both experimental and numerical methods. The focus of the study is on the vortex shedding and vortex interactions occurring in the step cylinder wake. Flow visualization with hydrogen bubble technique and planar Laser Induced Fluorescence has shown that three distinct spanwise vortex cells form: a single vortex shedding cell in the wake of the small cylinder and two vortex shedding cells in the wake of the large cylinder. Vortex connections form between the spanwise vortices in these cells downstream of the step, and vortex dislocations occur at cell boundaries. Complementary to the experimental tests, an LES-RANS hybrid numerical simulation is used to model the flow development. A comparison of the experimental and numerical results indicates that the numerical approach adequately models vortex dynamics in the wake of a step cylinder and, thus, may be used to analyze time dependent, three-dimensional flow topology which is difficult to characterize quantitatively using experimental methods.

Estimation of Ballistic Limit Velocities for Woven Composite Beams

2009 ◽  
Author(s):  
E. Sevkat ◽  
B. M. Liaw ◽  
F. Delale ◽  
B. B. Raju
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Damage Model ◽  
Experimental Tests ◽  
Composite Beams ◽  
Ballistic Limit ◽  
Gas Gun ◽  
Graphite Fibers ◽  
Ballistic Limit Velocity ◽  
Good Agreement

This paper presents an experimental and numerical study to estimate ballistic limit velocity, V50, of plain-weave hybrid S2 glass-IM7 graphite fibers/toughened SC-79 resin (cured at 177°C) composite beams. The tests were conducted on hybrid S2 glass-IM7 graphite fibers/toughened SC-79 resin and nonhybrid S2 glass-fiber/toughened SC-79 resin composites beams using high-speed gas-gun. The ballistic impact tests were then modeled using 3-D dynamic nonlinear finite element (FE) code, LS-DYNA, modified with a proposed user-defined nonlinear-orthotropic damage model. The ballistic limit velocities, V50, for both composite beams were then estimated using (a) only experimental tests, (b) combined experimental and numerical tests, (c) FE calculated residual velocities, and (d) FE calculated residual and transferred energies. For each type of composite beams, the parameters for the well-known Lambert-Jones equation were also computed. Good agreement between experimental and numerical results was observed.

Numerical Study of Long Channel Carbon Nanotube Based Transistors by Considering Variation in CNT Diameter

2020 ◽  
Vol 61 ◽  
pp. 78-87
Author(s):  
Sajjad Dehghani
Keyword(s):  
Carbon Nanotube ◽  
Chemical Sensors ◽  
Field Effect Transistors ◽  
Numerical Study ◽  
Electrical Current ◽  
Light Emitters ◽  
Short Channel ◽  
Numerical Studies ◽  
Long Channel ◽  
Good Agreement

While much numerical studies have been done on short channel carbon nanotube field effect transistors (CNT-FETs), there are only a few numerical reports on long channel devices. Long channel CNT-FETs have been widely used in chemical sensors and biosensors as well as light emitters. Therefore, numerical study is helpful for a better understanding of the behavior of such devices. In this paper, we numerically analyze long-channel CNT-FETs by solving the continuity and charge equations self-consistently. To increase the accuracy of simulation, filed-dependent mobility is applied to the equations. Furthermore, a method is proposed to obtain the electrical current of transistors as a function of CNT diameter. Obtained results are in good agreement with the previous experimental data. It is found that compared to a CNT-based resistor, the dependence of current on diameter is much higher in a CNT-FET. Finally, reproducibility of transistors based on the arrays of random CNTs of 1-2 nm diameter in terms of the CNTs number is also investigated.

Experimental and Numerical Study for Gap Resonance of Drillship Moonpool in Waves With/Without Forward Speed

2018 ◽  
Author(s):  
Allan R. Magee ◽  
Aichun Feng ◽  
Kandasamy Karthikeyan ◽  
Xiang Liu ◽  
Deguang Yan
Keyword(s):  
Numerical Study ◽  
Resonance Phenomenon ◽  
Forward Speed ◽  
Following Seas ◽  
Wave Flume ◽  
Trapped Mode ◽  
Numerical Studies ◽  
Gap Resonance ◽  
Piston Mode ◽  
Good Agreement

Experimental and numerical studies are carried out to examine the moonpool gap resonance for a drillship at both stationary position and forward speed conditions. The moonpool size and draft are also changed to study their effects for the gap resonance phenomenon. An OpenFOAM based CFD model is developed and the numerical results show good agreement with model tests. Both piston and sloshing modes gap resonances are clearly observed. The study shows that the resonance frequency and RAO of the wave elevation inside the moonpool are subject to the effects of moonpool length, drill ship draft and ship forward speed. The model test shows that moonpool elevation RAO generally significantly increases in head seas and noticeably decreases in following seas condition. It is interesting to notice that the wave flume sidewall significantly depresses the moonpool elevation RAO at a certain frequency regardless of moonpool length and draft. Further study shows that the presence of the flume sidewall results in a trapped mode that coincides with the moonpool piston mode resonance at zero speed. This depresses the peak of the moonpool resonance, which occurs at the same frequency.

Investigation on trim control of semi-planing amphibious cargo truck using experimental and numerical approaches

2021 ◽  
pp. 095440622110214
Author(s):  
Chengliang Sun ◽  
Xiaojun Xu ◽  
Tengan Zou
Keyword(s):  
Experimental Tests ◽  
Numerical Results ◽  
Maximum Speed ◽  
Key Indicator ◽  
Numerical Studies ◽  
Resistance Reduction ◽  
Speed Up ◽  
Good Agreement ◽  
Numerical Approaches

Speed on water is a key indicator of amphibious vehicles. However, due to the inherent non-streamlined configuration, when reaching a certain velocity, the resistance acting on the vehicle hull is so large and the maximum speed on water is hard to be further enhanced. Moreover, the trim gets so larger that leads the stern submerged into water when speed up. In order to solve this problem of a semi-planing amphibious cargo truck, this paper proposed a method by installing interceptors, hydrofoils, and combination of them on the stern. Experimental tests and numerical studies were performed respectively, and the numerical results were in good agreement with experiment. In what continues, the effect of interceptors, hydrofoils, and combination of them on trim and resistance was investigated. The results showed that the interceptor had a better effect than hydrofoil when height is not so big, but the effect got more and more powerful with interceptor height increasing, finally lead to an excessive trim control. Combination of interceptor with hydrofoil in suitable size were beneficial to trim control and resistance reduction.

scholarly journals Numerical Study of a Journal Bearing with Scratches: Validation with Literature and Comparison with Experimental Data

Lubricants ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 61
Author(s):  
Anh T. Vo ◽  
Michel Fillon ◽  
Jean Bouyer
Keyword(s):  
Scientific Literature ◽  
Journal Bearing ◽  
Numerical Study ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Test Rig ◽  
Numerical Studies ◽  
Clear Idea ◽  
Volume Method ◽  
Good Agreement

The lifespan of journal bearings is directly related to the operating conditions they have to face and reducing their maintenance intervals allows one to have a clear idea about their performance when issues occur. The presence of scratches on one of its surfaces degrades the performance of a journal bearing. These effects have already been assessed in experiments; however, numerical studies on this subject are still scarce. This work develops a numerical thermohydrodynamic (THD) program using the finite volume method to simulate the effects of scratches on the performance of journal bearings. To test the validity of the program, the numerical results are compared with the scientific literature and with experimental measurements conducted using the Pprime Institute journal bearing test rig. Some minor discrepancies are observed, but the overall results are in good agreement.

Advanced Experimental and Numerical Analysis of the Pressurized Air Wave Bearings

2007 ◽  
Author(s):  
Adrian Sescu ◽  
Florin Dimofte ◽  
Carmen Sescu ◽  
Abdollah A. Afjeh ◽  
Robert Handschuh
Keyword(s):  
Finite Difference ◽  
Reynolds Equation ◽  
Numerical Study ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Two Dimensional ◽  
Commercial Code ◽  
Type Boundary ◽  
Experimental Rig ◽  
Good Agreement

Experimental, analytical, and numerical investigations have been done in the field of gas lubrication, but few people focused on details of fluid flow between the sliding surfaces. In this work the entire pressurized wave bearing is analyzed in detail. The numerical study using a three-dimensional commercial code and a two-dimensional finite difference code gives information about the flow at many levels. The numerically computed flow rates using the commercial code are compared with experimental results determined at NASA Glenn Research Center on an experimental rig. The calculated discharge coefficient is used in the finite difference code which solves the Reynolds equation. The holes effect is considered as a source term, instead of applying hybrid type boundary conditions on the holes contours. Data from experimental tests, commercial three-dimensional code, and two-dimensional code are reported and compared to each other. Good agreement was found between numerical study and experiment.

Effects on Drillship Resistance of a Large Moonpool Using CFD Simulations With Experimental Validation

2016 ◽  
Author(s):  
Lucas do Vale Machado ◽  
Antonio Carlos Fernandes ◽  
Anis Altaf Hussain
Keyword(s):  
Oil And Gas ◽  
Numerical Study ◽  
Experimental Tests ◽  
Numerical Approach ◽  
Process Efficiency ◽  
Floating Structure ◽  
Cfd Models ◽  
Waves And Currents ◽  
Mesh Density ◽  
In Transit

Drillship is a marine vessel designed for drilling purposes of oil and gas wells. This kind of vessel has what is called a moonpool that is an opening on the base of the hull used for drilling operation. Nowadays, in search of better process efficiency, some of these drillships are being constructed with dual-derrick and are in need of a larger moonpool, which results in some effects on the floating structure, such as resistance increase. The main objective of this paper is to investigate the influence of shape and size of the moonpool on the resistance of a drillship dual derrick, while in transit. It presents the application of a commercial CFD (Computational Fluid Dynamics) software as a numerical approach to calculate the flow around a drillship without neglecting free surface effects. Throughout this work, the made assumptions, applied boundary conditions and appropriate mesh density studies are thoroughly discussed. Verification assessment is part of the work. In addition to the numerical study, some experimental tests were done at LOC/UFRJ (Laboratório de Ondas e Correntes – Laboratory of Waves and Currents) to validate the numerical approach. The comparison between simulation results and experiments allows the analysis of the present CFD models benefits and limitations, providing guidelines for similar future studies. The overall match between laboratory and virtual tests results supports the expansion of this procedure to other vessels and offshore floating units. The results of this work clarify the motion inside the moonpool and its effects. Furthermore, it gives the results of several different moonpool profiles that were optimized for this specific hull.

A Numerical Study of Squeeze Film Dampers

2013 ◽  
Author(s):  
Praneetha Boppa ◽  
Gerald L. Morrison ◽  
Aarthi Sekaran
Keyword(s):  
Steady State ◽  
High Speed ◽  
Numerical Study ◽  
Squeeze Film ◽  
Numerical Studies ◽  
Whirling Motion ◽  
Squeeze Film Dampers ◽  
Absolute Frame ◽  
Bearing System ◽  
Good Agreement

Squeeze film dampers (SFDs) are used in the high speed turbomachinery industry as a means to reduce vibration amplitude, provide damping, and improve dynamic stability of the rotor bearing system. Past numerical studies analyzing SFDs, have been computationally expensive and time consuming. The present study investigates the feasibility of applying a steady state solver to obtain computational efficiency while ensuring that the parameters of interest are captured. This is done via the application of the Moving Reference Frame (MRF) solver in ANSYS® Fluent. A steady state solver in an absolute frame of reference was used to produce whirling motion of the rotor. The results are validated by comparison to the experimental data of Delgado [1]. The numerical model shows good agreement with these results.

Experimental and Numerical Study of Volt-Ampere Characteristics of a Packed Tube Heated by Joule Heating

2021 ◽  
pp. 1-29
Author(s):  
Yi Ran Lu ◽  
Deepak Pudasainee ◽  
Md Khan ◽  
Rajender Gupta ◽  
Petr Nikrityuk
Keyword(s):  
Joule Heating ◽  
Numerical Study ◽  
Fixed Bed ◽  
Internal Heat ◽  
Packed Bed ◽  
Internal Diameter ◽  
Transfer Model ◽  
Numerical Studies ◽  
Chemically Reacting ◽  
Good Agreement

Abstract This work is devoted to experimental and numerical studies of volt-ampere characteristics of a fixed bed heated by the Joule heating. The main feature of this type of fixed bed is internal heat generation using the Joule heat. The application is to provide the heat to chemically reacting gases flowing through the bed reactor. To validate our model a cylindrical packed bed is considered with a height of 11 cm and an internal diameter of 4.8 cm. This bed is filled with 86 balls made of carbon steel with a diameter of 1/2 inches (1.27 cm). For numerical simulation, open-source DEM software is used to generate the cylindrical packed bed. Electric field distribution is calculated using a new particle-unresolved DEM-based model coupled with a discrete heat transfer model to account for the temperature dependency of the electrical conductivity of steel particles. The results of the simulation were found to be in good agreement with experimental data.

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