Gaseous Deflagration in Piping: Part 1 — Experimental Observations

2017 ◽  
Author(s):  
Thomas C. Ligon ◽  
David J. Gross ◽  
John C. Minichiello
Keyword(s):  
High Speed ◽  
Structural Response ◽  
Analysis And Design ◽  
Flame Acceleration ◽  
Pressure Time ◽  
Piping Systems ◽  
Time Histories ◽  
Short Test ◽  
Semi Empirical ◽  
Measured Pressure

The focus of this paper is on gaseous deflagration in piping systems and the corresponding implications on piping analysis and design. Unlike stable detonations that propagate at a constant speed and whose pressure-time histories can in some cases be predicted analytically, deflagration flame speeds and pressure-time histories are transient and depend on both the gas mixture and geometry of the pipe. This paper presents pressure and pipe strain data from gaseous deflagration experiments in long and short test apparatuses fabricated from either 2-inch or 4-inch diameter pipes. These data are used to demonstrate a spectrum of measured pressure-time histories and corresponding pipe response. It is concluded that deflagrations can be categorized as either “high” or “slow” speed with respect to pipe response. Slow deflagrations can be treated as quasi-static pressurizations, but high speed deflagrations can generate shock waves that dynamically excite the pipe. The existence of a transition from quasi-static to dynamic response has ramifications in regards to piping structural analysis and design, and a method for predicting the expected deflagration structural response using a semi-empirical flame acceleration model is proposed.

An analysis of the particle trajectories in spherical blast waves reflected from real and ideal surfaces

1981 ◽  
Vol 59 (10) ◽  
pp. 1380-1390 ◽  
Author(s):  
J. M. Dewey ◽  
D. J. McMillin
Keyword(s):  
High Speed ◽  
Ground Surface ◽  
Blast Waves ◽  
Particle Trajectories ◽  
Shock Interactions ◽  
Pressure Time ◽  
Time Histories ◽  
Particle Velocities ◽  
Spherical Shock ◽  
Fixed Times

High speed photogrammetry has been used to measure the particle trajectories in the flows resulting from the interaction of two identical explosively produced spherical shock waves. It is postulated that the interaction simulated the reflection of a spherical shock from an ideal nonenergy-absorbing surface. The "ideal" reflections were compared with reflections from two types of ground surface. From the observed particle trajectories the particle velocities, gas densities, and hydrostatic, dynamic, and total pressures in the complex air flows behind the shock interactions have been computed. These flows are described as two dimensional fields at fixed times and as time histories at fixed locations. The Mach stem shocks at the ground surfaces were weaker than those at corresponding positions near the interaction planes, but the magnitudes of the flow properties in these waves decreased more slowly and, at later times, became greater than those in the waves at the interaction planes. Computed pressure–time histories were compared to measurements made using electronic transducers and good agreement was found.

Experimental Investigation of Invar Edge Effect in Membrane LNG Tanks

2010 ◽  
Author(s):  
Mateusz Graczyk ◽  
Kjetil Berget ◽  
Joachim Allers
Keyword(s):  
Fluid Motion ◽  
Structural Response ◽  
Time History ◽  
Pressure Profile ◽  
Pressure Effects ◽  
Local Pressure ◽  
Temporal And Spatial Distribution ◽  
Containment System ◽  
Pressure Time ◽  
Time Histories

Sloshing, a violent fluid motion in tanks is of current interest for many branches of the industry, among them gas shipping. Although different methods are commonly combined for analyzing sloshing in LNG carriers, time histories of the pressure in the tanks are most reliably obtained by experiments. Very localized pressures may be important for the structural response of the tank containment system. Moreover, the typical pressure time history duration is similar to the structural natural frequency. Therefore, pressure measurements need to be performed with due account for temporal and spatial distribution. This requires a high sampling resolution both in time and space. Fine spatial resolution becomes especially important when local pressure effects are of interest, such as pressure profile passing a membrane corrugation of Mark III containment or Invar edge of No.96 containment. In this paper experimental approach applied by MARIN-TEK for analyzing sloshing phenomenon is presented. The focus is put on investigating effects of Invar edges. A transverse 2D model of a typical LNG carrier is used. Local pressure effects are investigated based on low filling level tests with different wall surfaces: smooth and with horizontal protrusions representing the surface similar to the No.96 containment system.

Two-Dimensional Simulation of Wave Propagation in a Three-Pipe Junction

2000 ◽  
Vol 122 (4) ◽  
pp. 549-555 ◽  
Author(s):  
R. J. Pearson ◽  
M. D. Bassett ◽  
P. Batten ◽  
D. E. Winterbone
Keyword(s):  
Wave Propagation ◽  
Adaptive Mesh Refinement ◽  
Adaptive Mesh ◽  
Finite Volume Scheme ◽  
Two Dimensional ◽  
Action Simulation ◽  
Pressure Time ◽  
Time Histories ◽  
Dimensional Simulation ◽  
Measured Pressure

The modelling of wave propagation in complex pipe junctions is one of the biggest challenges for simulation codes, particularly those applied to flows in engine manifolds. In the present work an inviscid two-dimensional model, using an advanced numerical scheme, has been applied to the simulation of shock-wave propagation through a three-pipe junction; the results are compared with corresponding schlieren images and measured pressure-time histories. An approximate Riemann solver is used in the shock-capturing finite volume scheme and the influence of the order of accuracy of the solver and the use of adaptive mesh refinement are investigated. The code can successfully predict the evolution and reflection of the wave fronts at the junctions whilst the run time is such as to make it feasible to include such a model as a local multi-dimensional region within a one-dimensional wave-action simulation of flow in engine manifolds. [S0742-4795(00)01304-1]

Unsteady Radial Flow of Gas Through Porous Media—Variable Viscosity and Compressibility

1956 ◽  
Vol 23 (1) ◽  
pp. 128-132
Author(s):  
J. S. Aronofsky ◽  
J. D. Porter
Keyword(s):  
Porous Media ◽  
High Speed ◽  
Gas Flow ◽  
Variable Viscosity ◽  
Substantial Effect ◽  
Massachusetts Institute Of Technology ◽  
Computer Laboratory ◽  
Pressure Time ◽  
Time Histories ◽  
Institute Of Technology

Abstract Calculations of pressure-time histories and flow rates are presented for radial unsteady flow of gases through porous media. Some nonideal gas properties are considered by expressing gas viscosity and gas compressibility (z-factor) as simple functions of pressure. These calculations were obtained by using the high-speed, electronic computer called “Whirlwind” which is located at the Digital Computer Laboratory of the Massachusetts Institute of Technology. The results demonstrate that variable viscosity and compressibility can exert a substantial effect on transient gas-flow systems. A simple means is suggested for estimating the velocity of gas flowing across an inner radial boundary into a hole when the gas pressure is held constant at that boundary.

scholarly journals Response of Piping Tees to Propagating Detonations

2013 ◽  
Author(s):  
Thomas C. Ligon ◽  
David J. Gross ◽  
Joseph E. Shepherd
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Structural Response ◽  
Initial Pressure ◽  
Finite Element Simulations ◽  
Steel Plates ◽  
Digital Data ◽  
304 Stainless Steel ◽  
Piping System ◽  
Piping Systems

This paper reports the results of experiments and finite element simulations on the structural response of piping systems to internal detonation loading. Specifically, the work described in this paper focuses on the forces that are produced at tee-junctions that lead to axial and bending structural responses of the piping system. Detonation experiments were conducted in a 2-in. (50 mm) diameter schedule 40 piping system that was fabricated using 304 stainless steel and welded to ASME B31.3 standards. The 4.1 m (162-in.) long piping system included one tee and was supported using custom brackets and cantilever beams fastened to steel plates that were bolted to the laboratory walls. Nearly-ideal detonations were used in a 30/70 H2-N2O mixture at 1 atm initial pressure and 300 K. Pressure and hoop, axial, and support strains were measured using a high-speed (1 MHz) digital data acquisition system and calibrated signal conditioners. It was concluded that detonations propagate through the run of a 90° tee with relatively little disturbance in either direction. The detonation load increases by approximately a factor of 2 when the detonation enters through the branch. The deflections of the cantilever beam supports and the hoop and axial pipe strains could be adequately predicted by finite element simulations. The support loads are adequately predicted as long as the supports are constrained to the piping. This paper shows that with relatively simple models, quantitative predictions of tee forces can be made for the purposes of design or safety analysis of piping systems subject to internal detonations.

Velocity Oscillation and Pressure Drop in Water–Air Slug Flow

2012 ◽  
Author(s):  
Ken Yamamoto ◽  
Satoshi Ogata
Keyword(s):  
Theoretical Model ◽  
Pressure Drop ◽  
Velocity Fluctuation ◽  
Slug Flow ◽  
High Speed ◽  
Scaling Analysis ◽  
Two Phase ◽  
Semi Empirical ◽  
Measured Pressure ◽  
Circular Microchannels

Visualization and pressure drop measurements of water–air two-phase flow in circular microchannels (d = 486 μm) was conducted. In order to investigate effects of the flow rates and T-junction size on the pressure drop of the two-phase slug flow, three test channels containing various T-junctions (136, 194, and 252 μm) were prepared. The measured pressure drop was compared with the results from semi-empirical model and theoretical model, and it was found that the experimental data generally agreed with the theoretical model. However, the pressure drop increased as the T-junction size decreased. In order to detect the causes of this increase in pressure drop, effects of the velocity fluctuation on the pressure drop were investigated. The velocity fluctuations were measured from the recorded images that were obtained by a high-speed camera. Although it was found that the instantaneous velocity fluctuated in large amplitudes and its cycle was synchronized with a period of the bubble pinch-off, the effects of the velocity fluctuation were negligible on the pressure drop. Finally, from a scaling analysis, it was suggested that the bubble overpressure was the cause of the increase in pressure drop.

scholarly journals Evaluation of earthquake response of low-rise structures using design codes and local specifications

1983 ◽  
Vol 16 (4) ◽  
pp. 331-344
Author(s):  
G. L. Hutchinson ◽  
A. Navidi
Keyword(s):  
Earthquake Engineering ◽  
Structural Response ◽  
Response Spectra ◽  
Building Code ◽  
Earthquake Response ◽  
Engineering Research ◽  
Analysis And Design ◽  
High Rise ◽  
Time Histories ◽  
Local Specifications

Most earthquake engineering research projects are concerned with the analysis and design of high-rise buildings. Comparisons of
actual earthquake forces with pseudo-static design forces recommended
by various building codes indicate that in actual earthquakes the forces in low-rise buildings can be up to three to five times the pseudo-static design forces. This paper is concerned with evaluating and comparing the earthquake response of low-rise buildings calculated using local response spectra and real time-histories with various Building Code Recommendations. It is shown that Building Code Recommendations underestimate the
structural response.

Analysis and design of thermo-mechanical interfaces

2012 ◽  
Vol 60 (2) ◽  
pp. 205-213
Author(s):  
K. Dems ◽  
Z. Mróz
Keyword(s):  
Optimality Conditions ◽  
Mechanical Loading ◽  
Material Properties ◽  
Structural Response ◽  
External Boundary ◽  
Mechanical Loads ◽  
Internal Interface ◽  
Analysis And Design ◽  
First Order ◽  
Mechanical Nature

Abstract. An elastic structure subjected to thermal and mechanical loading with prescribed external boundary and varying internal interface is considered. The different thermal and mechanical nature of this interface is discussed, since the interface form and its properties affect strongly the structural response. The first-order sensitivities of an arbitrary thermal and mechanical behavioral functional with respect to shape and material properties of the interface are derived using the direct or adjoint approaches. Next the relevant optimality conditions are formulated. Some examples illustrate the applicability of proposed approach to control the structural response due to applied thermal and mechanical loads.

An Experimental Investigation of the Auto-Ignition Properties of Two C5 Esters: Methyl Butanoate and Butyl Methanoate

2007 ◽  
Author(s):  
Stephen M. Walton ◽  
Carlos Perez ◽  
Margaret S. Wooldridge
Keyword(s):  
Low Temperature ◽  
High Speed ◽  
Combustion Engine ◽  
Low Temperature Combustion ◽  
Moderate Pressure ◽  
Molecular Weights ◽  
Auto Ignition ◽  
Methyl Butanoate ◽  
Temperature Combustion ◽  
Time Histories

Ignition studies of two small esters were performed using a rapid compression facility (RCF). The esters (methyl butanoate and butyl methanoate) were chosen to have matching molecular weights, and C:H:O ratios, while varying the lengths of the constituent alkyl chains. The effect of functional group size on ignition delay time was investigated using pressure time-histories and high speed digital imaging. The mixtures studied covered a range of conditions relevant to oxygenated fuels and fuel additives, including bio-derived fuels. Low temperature and moderate pressure conditions were selected for study due to their relevance to advanced low temperature combustion strategies, and internal combustion engine conditions. The results are discussed in terms of the reaction pathways affecting the ignition properties.

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