Maximum Missile Velocity From Boiling-Liquid Expanding-Vapor Explosions (BLEVE) Using Exergy Analysis

2012 ◽  
Author(s):  
Juan C. Ramirez ◽  
Suzanne A. Smyth ◽  
Russell A. Ogle
Keyword(s):  
High Pressure ◽  
Kinetic Energy ◽  
Exergy Analysis ◽  
Initial Conditions ◽  
Saturated Vapor ◽  
Pure Component ◽  
Estimation Methods ◽  
Buffer Zones ◽  
Boiling Liquid ◽  
Dead State

One of the hazards from a boiling liquid expanding vapor explosion (BLEVE) is the formation and projection of missiles. The design of safeguards for protection from missiles, such as barricades or buffer zones, requires an estimate of the maximum kinetic energy of the missiles. In this paper we demonstrate the use of exergy analysis to estimate the maximum available work of the explosion, and then use a modified Gurney method to estimate the partitioning of exergy into the kinetic energy of the saturated vapor, the saturated liquid, and the missiles. The advantage of using exergy analysis to evaluate the maximum work of an explosion is that exergy is a state variable: its value depends only on the initial conditions of the high pressure fluid and the specification of the dead state. The advantage of using the Gurney method for evaluating the kinetic energy of missiles is that it does not require the selection of an equation of state for the high pressure fluid. The methodology is illustrated for several pure component fluids, and is then compared with other estimation methods.

BLEVE Energy and Aerosol Formation: An Exergy Analysis

2014 ◽  
Author(s):  
Juan C. Ramirez ◽  
Suzanne A. Smyth ◽  
Russell A. Ogle
Keyword(s):  
Exergy Analysis ◽  
Initial Conditions ◽  
Pure Component ◽  
Bulk Liquid ◽  
Initial Kinetic Energy ◽  
Aerosol Formation ◽  
State Variable ◽  
Dead State ◽  
Surface Work ◽  
Maximum Work

The hazards from a boiling liquid expanding vapor explosion (BLEVE) include the formation of a blast wave and the projection of missiles. To understand the maximum work that can be obtained from a BLEVE, the authors have investigated in previous publications certain aspects of BLEVE behavior using exergy analysis. One of the key limitations in relating exergy calculations to more realistic behavior is the lack of knowledge of how the exergy of the explosion is partitioned into various types of work that occur in the BLEVE process. Some of these work terms include the formation and propagation of a shock wave, the strain work of vessel deformation and rupture into missiles, the initial kinetic energy of the missiles, and the surface work of aerosol droplet formation. In this paper we explore one of these work terms, the surface work performed in transforming the bulk liquid into aerosol droplets. The advantage of using exergy analysis to evaluate the maximum work of an explosion is that exergy is a state variable: its value depends only on the initial conditions of the high pressure fluid and the specification of the dead state. The methodology is illustrated for several pure component fluids.

scholarly journals Development of a two zone turbulence model and its application to the cycle-simulation

2014 ◽  
Vol 18 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Momir Sjeric ◽  
Darko Kozarac ◽  
Rudolf Tomic
Keyword(s):  
High Pressure ◽  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Turbulence Model ◽  
Combustion Process ◽  
Progress Variable ◽  
Cycle Simulation ◽  
Pressure Cycle ◽  
Turbulent Flow Field

The development of a two zone k-? turbulence model for the cycle-simulation software is presented. The in-cylinder turbulent flow field of internal combustion engines plays the most important role in the combustion process. Turbulence has a strong influence on the combustion process because the convective deformation of the flame front as well as the additional transfer of the momentum, heat and mass can occur. The development and use of numerical simulation models are prompted by the high experimental costs, lack of measurement equipment and increase in computer power. In the cycle-simulation codes, multi zone models are often used for rapid and robust evaluation of key engine parameters. The extension of the single zone turbulence model to the two zone model is presented and described. Turbulence analysis was focused only on the high pressure cycle according to the assumption of the homogeneous and isotropic turbulent flow field. Specific modifications of differential equation derivatives were made in both cases (single and two zone). Validation was performed on two engine geometries for different engine speeds and loads. Results of the cyclesimulation model for the turbulent kinetic energy and the combustion progress variable are compared with the results of 3D-CFD simulations. Very good agreement between the turbulent kinetic energy during the high pressure cycle and the combustion progress variable was obtained. The two zone k-? turbulence model showed a further progress in terms of prediction of the combustion process by using only the turbulent quantities of the unburned zone.

MULTI–INERT OSCILLATORY MECHANISM

2020 ◽  
Vol 2 ◽  
pp. 19-25
Author(s):  
I.P. POPOV
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Oscillation Frequency ◽  
Free Oscillation ◽  
Initial Conditions ◽  
Oscillatory System ◽  
Harmonic Oscillations ◽  
Oscillatory Systems ◽  
Oscillatory Mechanism ◽  
Mutual Conversion

A mechanical oscillatory system with homogeneous elements, namely, with n massive loads (multi– inert oscillator), is considered. The possibility of the appearance of free harmonic oscillations of loads in such a system is shown. Unlike the classical spring pendulum, the oscillations of which are due to the mutual conversion of the kinetic energy of the load into the potential energy of the spring, in a multi–inert oscillator, the oscillations are due to the mutual conversion of only the kinetic energies of the goods. In this case, the acceleration of some loads occurs due to the braking of others. A feature of the multi–inert oscillator is that its free oscillation frequency is not fixed and is determined mainly by the initial conditions. This feature can be very useful for technical applications, for example, for self–neutralization of mechanical reactive (inertial) power in oscillatory systems.

Consistent Theoretical Model of Mean Diameter and Size Distribution by Liquid Sheet Atomization

2012 ◽  
Author(s):  
Chihiro Inoue ◽  
Toshinori Watanabe ◽  
Takehiro Himeno ◽  
Seiji Uzawa ◽  
Mitsuo Koshi
Keyword(s):  
Theoretical Model ◽  
Kinetic Energy ◽  
Droplet Diameter ◽  
Velocity Profiles ◽  
Liquid Sheet ◽  
Estimation Methods ◽  
Liquid Jets ◽  
Injection Velocity ◽  
Size Distributions ◽  
Mean Diameter

A consistent theoretical model is proposed and validated for calculating droplet diameters and size distributions. The model is derived based on the energy conservation law including the surface free energy and the Laplace pressure. Under several hypotheses, the law derives an equation indicating that atomization results from kinetic energy loss. Thus, once the amount of loss is determined, the droplet diameter is able to be calculated without the use of experimental parameters. When the effects of ambient gas are negligible, injection velocity profiles of liquid jets are the essential cause of the reduction of kinetic energy. The minimum Sauter mean diameter produced by liquid sheet atomization is inversely proportional to the injection Weber number when the injection velocity profiles are laminar or turbulent. A non-dimensional distribution function is also derived from the mean diameter model and Nukiyama-Tanasawa’s function. The new estimation methods are favorably validated by comparing with corresponding mean diameters and the size distributions, which are experimentally measured under atmospheric pressure.

Method for Selecting Master Degrees of Freedom for Rotating Substructure

2014 ◽  
Author(s):  
Yanfei Zuo ◽  
Jianjun Wang ◽  
Weimeng Ma ◽  
Xue Zhai ◽  
Xinyu Yao
Keyword(s):  
High Pressure ◽  
Kinetic Energy ◽  
Degrees Of Freedom ◽  
Original Model ◽  
Dynamic Coupling ◽  
Stationary Reference Frame ◽  
Model Size ◽  
Gyroscopic Effects ◽  
Localized Damping ◽  
Frame Frequency

A method of selecting master degrees of freedom (DOFs) for rotating substructure is presented in this paper to obtain reduced 3D rotor models. Fixed modes of the substructure below thrice the operating frequency are analyzed. According to each mode shape, the DOFs at where main kinetic energy locates are selected as master DOFs to decrease missing of dynamic coupling. Additional DOFs may be selected based on traditional substructure method. In the stationary reference frame, frequency-dependent gyroscopic effects can be included as damping matrices changing with spin speed. Besides, by selecting appropriate substructure, localized damping and key parts of the rotor for analysis can be kept the same as the original model. A reduced model of a high pressure rotor amply demonstrated the capability of the method in reducing the model size and increasing the computational efficiency with less than two percent error.

scholarly journals GRAVITY HEATS THE UNIVERSE

2009 ◽  
Vol 18 (14) ◽  
pp. 2201-2207
Author(s):  
ADAM MOSS ◽  
DOUGLAS SCOTT
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Energy Conservation ◽  
Cosmic Microwave Background ◽  
Initial Conditions ◽  
Gravitational Instability ◽  
Simplified Model ◽  
Microwave Background ◽  
Average Temperature ◽  
The Universe

Structures in the Universe grew through gravitational instability from very smooth initial conditions. Energy conservation requires that the growing negative potential energy of these structures be balanced by an increase in kinetic energy. A fraction of this is converted into heat in the collisional gas of the intergalactic medium. Using a toy model of gravitational heating, we attempt to link the growth of structure in the Universe with the average temperature of this gas. We find that the gas is rapidly heated from collapsing structures at around z ~ 10, reaching a temperature > 106 K today, depending on some assumptions of our simplified model. Before that there was a cold era from z ~ 100 to ~10 in which the matter temperature was below that of the cosmic microwave background.

Towards an Exergy-Based Explosion Energy Model for Boiling-Liquid Expanding-Vapor Explosions

2011 ◽  
Author(s):  
Juan C. Ramirez ◽  
Suzanne A. Smyth ◽  
Russell A. Ogle
Keyword(s):  
Pressure Vessel ◽  
Ambient Pressure ◽  
Maximum Energy ◽  
Explosion Energy ◽  
Superheated Liquid ◽  
Boiling Liquid ◽  
Dead State ◽  
Vapor Explosions ◽  
The Dead ◽  
Definition Of

A boiling liquid, expanding vapor explosion (BLEVE) occurs when a pressure vessel containing a superheated liquid undergoes a catastrophic failure, resulting in a violent vaporization of the liquid. The exposure of a pressure vessel to a fire is a classic scenario that can result in a BLEVE. The thermomechanical exergy of a pressure vessel’s contents provides — by definition — an upper bound on the work that can be performed by the system during the explosion. By fixing the values of ambient pressure and temperature (i.e., the dead state), exergy can be interpreted as another thermodynamic property. This rigorous and unambiguous definition makes it ideal to estimate the maximum energy of explosions. The numerical value of exergy depends on the definition of the dead state. In this paper we examine the effect of different definitions for the dead state on the explosion energy value. We consider two applications of this method: the contribution of the vapor head-space to the explosive energy as a function of the fractional liquid fill of the vessel, and the effect of the vessel burst pressure.

First and Second Law Analysis of Intercooled Turbofan Engine

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Xin Zhao ◽  
Oskar Thulin ◽  
Tomas Grönstedt
Keyword(s):  
High Pressure ◽  
Conceptual Design ◽  
Exergy Analysis ◽  
Second Law ◽  
Turbofan Engine ◽  
Blade Height ◽  
Turbofan Engines ◽  
Fuel Burn ◽  
Aero Engine ◽  
Last Stage

Although the benefits of intercooling for aero-engine applications have been realized and discussed in many publications, quantitative details are still relatively limited. In order to strengthen the understanding of aero-engine intercooling, detailed performance data on optimized intercooled (IC) turbofan engines are provided. Analysis is conducted using an exergy breakdown, i.e., quantifying the losses into a common currency by applying a combined use of the first and second law of thermodynamics. Optimal IC geared turbofan engines for a long range mission are established with computational fluid dynamics (CFD) based two-pass cross flow tubular intercooler correlations. By means of a separate variable nozzle, the amount of intercooler coolant air can be optimized to different flight conditions. Exergy analysis is used to assess how irreversibility is varying over the flight mission, allowing for a more clear explanation and interpretation of the benefits. The optimal IC geared turbofan engine provides a 4.5% fuel burn benefit over a non-IC geared reference engine. The optimum is constrained by the last stage compressor blade height. To further explore the potential of intercooling the constraint limiting the axial compressor last stage blade height is relaxed by introducing an axial radial high pressure compressor (HPC). The axial–radial high pressure ratio (PR) configuration allows for an ultrahigh overall PR (OPR). With an optimal top-of-climb (TOC) OPR of 140, the configuration provides a 5.3% fuel burn benefit over the geared reference engine. The irreversibilities of the intercooler are broken down into its components to analyze the difference between the ultrahigh OPR axial–radial configuration and the purely axial configuration. An intercooler conceptual design method is used to predict pressure loss heat transfer and weight for the different OPRs. Exergy analysis combined with results from the intercooler and engine conceptual design are used to support the conclusion that the optimal PR split exponent stays relatively independent of the overall engine PR.

Exergy Analysis-Potential of Salinity Gradient Energy Source

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Arash Emdadi ◽  
Mansour Zenouzi ◽  
Amir Lak ◽  
Behzad Panahirad ◽  
Yunus Emami ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Exergy Analysis ◽  
Salinity Gradient ◽  
Electrical Energy ◽  
Dead State ◽  
Gradient Energy ◽  
Reference Environment ◽  
Faster Development

Mixing of fresh (river) water and salty water (seawater or saline brine) in a controlled environment produces an electrical energy known as salinity gradient energy (SGE). Two main conversion technologies of SGE are membrane-based processes: pressure retarded osmosis (PRO) and reverse electrodialysis (RED). Exergy calculations for a representative river-lake system are investigated using available data in the literature between 2000 and 2008 as a case study. An exergy analysis of an SGE system of sea-river is applied to calculate the maximum potential power for electricity generation. Seawater is taken as reference environment (global dead state) for calculating the exergy of fresh water since the sea is the final reservoir. Aqueous sodium chloride solution model is used to calculate the thermodynamic properties of seawater. This model does not consider seawater as an ideal solution and provides accurate thermodynamics properties of sodium chloride solution. The chemical exergy analysis considers sodium chloride (NaCl) as main salt in the water of this highly saline Lake with concentration of more than 200 g/L. The potential power of this system is between 150 and 329 MW depending on discharge of river and salinity gradient between the Lake and the River based on the exergy results. This result indicates a high potential for constructing power plant for SGE conversion. Semipermeable membranes with lifetime greater than 10 years and power density higher than 5 W/m2 would lead to faster development of this conversion technology.

scholarly journals Preliminary Study on Kinetic Energy Distributions of Ar+ Fragments Resulting From Ar3+ Visible Photodissociation

1991 ◽  
Vol 11 (2) ◽  
pp. 95-98 ◽  
Author(s):  
F. X. Gadea ◽  
J. Durup
Keyword(s):  
Kinetic Energy ◽  
Theoretical Study ◽  
Initial Conditions ◽  
Dipole Moments ◽  
Energy Distributions ◽  
Transition Dipole ◽  
Transition Dipole Moments ◽  
Dissociation Dynamics ◽  
Total Energies ◽  
Preliminary Study

According to a strategy which involves DIM excitonic Hamiltonian, DIM-like transition dipole moments, realistic dynamical propagations with the HWD method (Hemiquantal dynamics with the Whole DIM basis), and the Wigner function to weight the initial conditions, a non-empirical theoretical study of the kinetic energy distribution of the Ar+ photofragments is performed for three total energies. The results illustrate the dominant symmetric stretching motion and the importance of non-adiabatic effects in the Ar3+ dissociation dynamics.

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