Numerical and Experimental Studies of Ballistic Compression Process in a Soft Recovery System

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Girijesh Mathur ◽  
Nachiketa Tiwari ◽  
Neha Chaturvedi
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Experimental Studies ◽  
Pressure Rise ◽  
Sensitivity Analyses ◽  
Design Parameters ◽  
Strong Positive Correlation ◽  
Compression Process ◽  
Recovery System ◽  
Two Parameters

Abstract A ballistic compression type soft recovery system can stop a free-flying supersonic projectile in a controlled manner. The moment such a projectile enters the System, a normal shock gets created and starts hurtling down, to kick off a train of events involving shock reflections, diaphragm rupture, shock merger, creation of new shocks and contact discontinuities, and expansion wave-shock interactions. A good understanding of these phenomena and sensitivity of the System's performance to changes in design parameters is needed to design an efficient soft recovery system. Unfortunately, not much information is available about this. The present work fills this gap. We have developed a numerical model for the system and conducted sensitivity analyses using four design parameters; pressure, molecular weight, the ratio of specific heats, and temperature of gas used in the system. We show that while there is a strong, positive correlation between the first two parameters and projectile deceleration, the other two parameters are less critical. We conducted experiments to corroborate our conclusions and improve our numerical model. Post such improvements, we found the difference between simulation and experimental data to be acceptable. Experiments also confirmed the findings of our sensitivity studies. Finally, we conducted a two-dimensional finite volume analysis to understand the reasons underlying the residual difference between our numerical and experimental data. We show that such differences are due to pressure-rise at a point once a shock passes by it, and such a rise in pressure is attributable to boundary layer effects.

Comparison of a Cavity Solar Receiver Numerical Model and Experimental Data

1990 ◽  
Vol 112 (3) ◽  
pp. 183-190 ◽  
Author(s):  
R. E. Hogan ◽  
R. B. Diver ◽  
Wm. B. Stine
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Convective Heat ◽  
Operating Conditions ◽  
Solar Furnace ◽  
Sensitivity Analyses ◽  
Test Bed ◽  
Transfer Rates ◽  
Solar Receiver ◽  
Solar Energy Input

Results from a numerical model of axisymmetric solar cavity receivers are compared with experimental data for tests of a novel test bed receiver in the Sandia National Laboratories solar furnace. The computed energy transfer rates and temperatures are compared with the experimental data for different receiver geometries, aperture sizes, and operating conditions. In general, the agreement between the numerical model and the experimental data is better for the small-to-midsized apertures than for the large apertures. The analysis indicates that for the larger apertures, the convective heat losses are over predicted. It also suggests that these losses could be better characterized. Sensitivity analyses show that both the total solar energy input rate and the convective heat-loss coefficient significantly affect the receiver thermal performance and that the distribution of the input solar flux significantly affects the temperature distribution in the receiver.

A Rim Seal Orifice Model With 2 Cds and Effects of Swirl in Seals

2008 ◽  
Author(s):  
Bruce V. Johnson ◽  
Cheng-Zhang Wang ◽  
Ramendra P. Roy
Keyword(s):  
Experimental Data ◽  
Flow Condition ◽  
Gas Turbines ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Outer Region ◽  
Outer Radius ◽  
Lumped Parameter ◽  
Flow Through ◽  
Two Parameters

Rim seal ingestion models for gas turbines are formulated to estimate the amount of hot fluid ingested through “clearance” seals into the disk cavity. Previous numerical and experimental studies showed the complex time-dependent, three-dimensional characteristics of the flow through the seals and in the outer region of the disk cavity. The present model is developed for estimating ingress and egress flow through the seal that is driven by the azimuthal variation in gas path pressure near the vane and blade platforms. Most published rim seal orifice models have used one “lumped parameter” Cd for both ingress and egress across the seal. However, the flow path from the gas path through the seal is often more convoluted than the flow returning to the gas path. The present Rim Seal Orifice Model includes (i) a Cd value for ingress from the gas path into the disk cavity, (ii) a Cd value for egress from the disk cavity to the gas path and (iii) an estimate for effects of swirl from the seal outer radius to the inner radius of the seal mixing region. The use of two Cd values provides two parameters for characterizing the flow through the seal. The ingress and egress Cd values for a turbine rim seal configuration and flow condition are estimated by comparing the modeled seal effectiveness for a parametric range of ingress and egress Cd values with experimental stator wall measurements. The combination of Cd values, which best matches experimental data over a range of coolant flow ratios, characterizes the seal and flow condition. Arizona State University experimental data were used to estimate the Cd values for an overlap seal configuration.

scholarly journals MODEL OF THE QUALITY-POWER INDICATOR OF A ROTARY DRUM MIXER

2020 ◽  
pp. 107-113
Author(s):  
А.В. Чупшев ◽  
В.В. Коновалов ◽  
К.П. Фудин
Keyword(s):  
Experimental Data ◽  
Initial Data ◽  
Statistical Model ◽  
Quality Indicators ◽  
Experimental Studies ◽  
Calculated Data ◽  
Design Parameters ◽  
Operating Parameters ◽  
Drum Mixer ◽  
Rotary Drum

На основании экспериментальных исследований в статье изложены вопросы повышения качественных показателей работы барабанного смесителя кормов, представлено описание его конструкции и принцип работы. Исследования проводились в соответствии с действующей методикой и материалами, представленными в статье. По результатам аппроксимации исходно рассчитанных значений качественно-мощностного показателя получена статистическая модель данного качественно-мощностного показателя (0,01 %∙кВт). Осуществлен анализ величины ошибок расчетных данных на предмет соответствия исходным данным. После обработки полученных экспериментальных данных приведено описание графических зависимостей по влиянию конструктивных параметров рабочего органа барабанного смесителя на качественно-мощностной показатель. Увеличение высоты установки лопастей нежелательно свыше 0,16 м, а увеличение количества лопастей свыше восемь штук приводит к резкому ухудшению количественно-мощностного показателя. Даны соответствующие выводы по применению исследуемых конструктивных и режимных параметров при работе барабанного смесителя. Based on experimental studies, the article presents the issues of improving the quality indicators of the drum feed mixer, describes its design and operating principle. The research was conducted in accordance with the current methodology and materials presented in the article. Based on the results of approximation of the initially calculated values of the quality-power indicator, a statistical model of this quality-power indicator (0.01% kW) is obtained. The value of errors in the calculated data is analyzed for correspondence with the initial data. After processing the obtained experimental data, the description of dependence diagrams on the influence of the design parameters of the working body of the drum mixer on the quality and power indicator is shown. An increase in the height of the installation of blades is undesirable over 0.16 m, and an increase in the number of blades over eight leads to a rapid deterioration in the quantity-power indicator. The relevant conclusions on the application of the studied design and operating parameters in the working of the drum mixer are presented.

Numerical Model of a Deep Surge Cycle in Low-Speed Centrifugal Compressor

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Grzegorz Liśkiewicz ◽  
Michał Kulak ◽  
Krzysztof Sobczak ◽  
Matthew Stickland
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Pressure Rise ◽  
Flow Structures ◽  
Centrifugal Blower ◽  
Cycle Frequency ◽  
Low Speed ◽  
Pressure Distributions ◽  
Important Input ◽  
Efficient Protection

Abstract In this article, a numerical model of the full surge cycle is presented for the low-speed centrifugal blower and compared with the experiment. Surge phenomenon is very dangerous for the compressor operation. Therefore, the possibility of studying its physics experimentally is strongly limited. The application of numerical methods allows one to safely analyze surge physics without causing risks to the operating crew. This article presents a description of the applied numerical method and exhaustive analysis of the flow structures observed at consecutive stages of the surge cycle. The surge is known to be very difficult to be simulated due to large timescale and region of influence. This study also shows the importance of an appropriate choice of the simulation definition and the boundary conditions. The presented method allows gathering information about features such as the regions of flow reversal, pressure distributions, pressure rise, cycle frequency, and others. All the aforementioned information provides important input to the efficient antisurge system design. The model has been validated by a comparison with the experimental data. Thanks to simulation, standardized antisurge solutions could be possibly replaced with more efficient protection schemes tailored to a given machine.

Deconvolution of gamma‐ray logs in the case of dipping radioactive zones

Geophysics ◽  
1981 ◽  
Vol 46 (2) ◽  
pp. 198-202 ◽  
Author(s):  
John G. Conaway
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Gamma Ray ◽  
Experimental Studies ◽  
Borehole Diameter ◽  
Dip Angle ◽  
Gamma Ray Log ◽  
Simple Numerical Model

It has been shown both theoretically and experimentally that the grade‐thickness product of a zone of uranium or other radioelement, computed on the basis of a gamma‐ray log, will vary inversely with the cosine of the angle between the radioactive zone and the normal to the borehole. I present experimental studies in model boreholes containing dipping radioactive zones, extending the theory of deconvolution of gamma‐ray logs to the case of dipping zones. The experimental data were found to agree well with a simple numerical model which takes into account borehole diameter, detector length, and thickness of the radioactive zone as well as dip angle.

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.

EXPERIMENTAL STUDIES OF REINFORCED CONCRETE STRUCTURES WITH CROSS-SHAPED SPATIAL CRACK UNDER TORSION WITH BENDING

2020 ◽  
Vol 92 (6) ◽  
pp. 13-25
Author(s):  
Vl.I. KOLCHUNOV ◽  
◽  
A.I. DEMYANOV ◽  
M.M. MIHAILOV ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Experimental Determination ◽  
Calculation Method ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Design Parameters ◽  
Reinforced Concrete Structures ◽  
Experimental Scheme

The article offers a method and program for experimental studies of reinforced concrete structures with cross-shaped spatial crack under torsion with bending, the main purpose of which is to check the design assumptions and experimental determination of the design parameters of the proposed calculation method. The conducted experimental studies provide an opportunity to test the proposed calculation apparatus and clarify the regularities for determining deflections, angles of rotation of extreme sections, and stresses in the compressed zone of concrete. For analysis, the article presents a typical experimental scheme for the formation and development of cracks in the form of a sweep, as well as characteristic graphs of the dependence of the angles of rotation of end sections.

scholarly journals Hydraulic Transients in Viscoelastic Pipeline System with Sudden Cross-Section Changes

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4071
Author(s):  
Michał Kubrak ◽  
Agnieszka Malesińska ◽  
Apoloniusz Kodura ◽  
Kamil Urbanowicz ◽  
Michał Stosiak
Keyword(s):  
Numerical Model ◽  
Cross Section ◽  
Laboratory Data ◽  
Experimental Studies ◽  
Distribution Networks ◽  
Water Hammer ◽  
Fluid Distribution ◽  
Pipeline System ◽  
Hydraulic Transients ◽  
Single Pipe

It is well known that the water hammer phenomenon can lead to pipeline system failures. For this reason, there is an increased need for simulation of hydraulic transients. High-density polyethylene (HDPE) pipes are commonly used in various pressurised pipeline systems. Most studies have only focused on water hammer events in a single pipe. However, typical fluid distribution networks are composed of serially connected pipes with various inner diameters. The present paper aims to investigate the influence of sudden cross-section changes in an HDPE pipeline system on pressure oscillations during the water hammer phenomenon. Numerical and experimental studies have been conducted. In order to include the viscoelastic behaviour of the HDPE pipe wall, the generalised Kelvin–Voigt model was introduced into the continuity equation. Transient equations were numerically solved using the explicit MacCormack method. A numerical model that involves assigning two values of flow velocity to the connection node was used. The aim of the conducted experiments was to record pressure changes downstream of the pipeline system during valve-induced water hammer. In order to validate the numerical model, the simulation results were compared with experimental data. A satisfactory compliance between the results of the numerical calculations and laboratory data was obtained.

scholarly journals Investigation of the Thickness Differential on the Formability of Aluminum Tailor Welded Blanks

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 875
Author(s):  
Jie Wu ◽  
Yuri Hovanski ◽  
Michael Miles
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Numerical Model ◽  
Plastic Strain ◽  
Finite Element Model ◽  
Equivalent Plastic Strain ◽  
Element Model ◽  
Dome Height ◽  
Tailor Welded Blanks ◽  
Simulation Results

A finite element model is proposed to investigate the effect of thickness differential on Limiting Dome Height (LDH) testing of aluminum tailor-welded blanks. The numerical model is validated via comparison of the equivalent plastic strain and displacement distribution between the simulation results and the experimental data. The normalized equivalent plastic strain and normalized LDH values are proposed as a means of quantifying the influence of thickness differential for a variety of different ratios. Increasing thickness differential was found to decrease the normalized equivalent plastic strain and normalized LDH values, this providing an evaluation of blank formability.

Robust Compressor Blades for Desensitizing Operational Tip Clearance Variations

2014 ◽  
Author(s):  
Pranay Seshadri ◽  
Shahrokh Shahpar ◽  
Geoffrey T. Parks
Keyword(s):  
Robust Design ◽  
Total Pressure ◽  
Pressure Rise ◽  
Side Surface ◽  
Tip Clearance ◽  
Design Parameters ◽  
Compressor Blades ◽  
Robust Designs ◽  
Multi Objective ◽  
Mean And Variance

Robust design is a multi-objective optimization framework for obtaining designs that perform favorably under uncertainty. In this paper robust design is used to redesign a highly loaded, transonic rotor blade with a desensitized tip clearance. The tip gap is initially assumed to be uncertain from 0.5 to 0.85% span, and characterized by a beta distribution. This uncertainty is then fed to a multi-objective optimizer and iterated upon. For each iteration of the optimizer, 3D-RANS computations for two different tip gaps are carried out. Once the simulations are complete, stochastic collocation is used to generate mean and variance in efficiency values, which form the two optimization objectives. Two such robust design studies are carried out: one using 3D blade engineering design parameters (axial sweep, tangential lean, re-cambering and skew) and the other utilizing suction and pressure side surface perturbations (with bumps). A design is selected from each Pareto front. These designs are robust: they exhibit a greater mean efficiency and lower variance in efficiency compared to the datum blade. Both robust designs were also observed to have significantly higher aft and reduced fore tip loading. This resulted in a weaker clearance vortex, wall jet and double leakage flow, all of which lead to reduced mixed-out losses. Interestingly, the robust designs did not show an increase in total pressure at the tip. It is believed that this is due to a trade-off between fore-loading the tip and obtaining a favorable total pressure rise and higher mixed-out losses, or aft-loading the tip, obtaining a lower pressure rise and lower mixed-out losses.

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