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Author: Yong Wook Kim
Publisher:
ISBN:
Category :
Languages : en
Pages : 57
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Book Description
The construction and operation of a heated shock tube (often called mercury shock tube due to its immediate application) are described in detail. Experimental observations of fluidmechanical interest on shock waves in mercury gas are presented, and discussed in the light of the preliminary theoretical investigation. (Author).
Author: Yong Wook Kim
Publisher:
ISBN:
Category :
Languages : en
Pages : 57
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Book Description
The construction and operation of a heated shock tube (often called mercury shock tube due to its immediate application) are described in detail. Experimental observations of fluidmechanical interest on shock waves in mercury gas are presented, and discussed in the light of the preliminary theoretical investigation. (Author).
Author: Daniel Robert Haylett
Publisher: Stanford University
ISBN:
Category :
Languages : en
Pages : 169
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Book Description
This thesis describes a new facility and method of experimentation, which can be used to study the combustion chemistry of low-volatility fuels in the gas phase. Two main goals are described: first, the development of the aerosol shock tube and procedures; and second, a demonstration of its capabilities. There is a lack of high-quality, accurate chemical kinetics data for the oxidation of large hydrocarbons, which are important for modeling diesel, rocket, or jet engines among other combustion systems. While conventional shock tubes are very effective reactor vessels for low-molecular-weight gaseous fuels (n-alkanes up to five carbon atoms), larger fuel molecules exist as low-volatility liquids/solids, and the vapor-pressures of these fuels are not large enough for high or even moderate fuel loadings. Heating the shock tube has extended the use of shock tubes to carbon numbers of 10 to 12, but beyond that, the high temperatures prior to the shock initiation can decompose the fuel, and (for fuel mixtures like diesel) can cause fractional distillation. The question is then: how can we study low-vapor-pressure fuels in a shock tube? The solution presented here, which avoids the problems associated with heating, is called the aerosol shock tube. In the aerosol shock tube, the fuel is injected as an aerosol of micron-size droplets. Then a series of shock waves first evaporate the fuel and subsequently raise the resultant purely gas-phase mixture to combustion-relevant temperatures. With proper selection of the shock strength and timing, this process effectively decouples the mass and heat transfer processes associated with evaporation from the chemical mechanism of combustion. This enables the study of extremely low-volatility fuels, never before studied in a purely gas-phase form in a shock tube. The first application of this new facility was to measure the ignition delay time for many previously inaccessible fuels in the gas-phase. In this thesis, we have measured ignition delay times for the pure surrogate fuel components n-decane, n-dodecane, n-hexadecane, and methyl decanoate as well as for multi-component fuels such as JP-7 and multiple different blends of diesel fuel. Taken over a range of conditions, these measurements provide sensitive validation targets for their respective chemical mechanisms. These data showed agreement with past heated shock tube experiments for fuels in which premature fuel decomposition is not an issue (n-decane and low concentration n-dodecane). However, when comparing heated and aerosol shock tube ignition delay times for fuels that require significant heating, like n-hexadecane, the existing heated shock tube data demonstrated evidence of premature decomposition. The second application to the study of chemical kinetics was to measure the concentration of important species during the decomposition and oxidation of select low-vapor-pressure fuels. These species time-histories provide much more information for kinetic mechanism refinement. Experiments were performed to measure the important OH radical and the stable intermediate C2H4 for both n-hexadecane and diesel. The number of important low-vapor-pressure fuels that require high-quality validation targets is large, and our new method for providing this data has proven very effective. This work enables the development of the next generation of accurate chemical mechanisms and will be essential to their success.
Author: Daniel Robert Haylett
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
This thesis describes a new facility and method of experimentation, which can be used to study the combustion chemistry of low-volatility fuels in the gas phase. Two main goals are described: first, the development of the aerosol shock tube and procedures; and second, a demonstration of its capabilities. There is a lack of high-quality, accurate chemical kinetics data for the oxidation of large hydrocarbons, which are important for modeling diesel, rocket, or jet engines among other combustion systems. While conventional shock tubes are very effective reactor vessels for low-molecular-weight gaseous fuels (n-alkanes up to five carbon atoms), larger fuel molecules exist as low-volatility liquids/solids, and the vapor-pressures of these fuels are not large enough for high or even moderate fuel loadings. Heating the shock tube has extended the use of shock tubes to carbon numbers of 10 to 12, but beyond that, the high temperatures prior to the shock initiation can decompose the fuel, and (for fuel mixtures like diesel) can cause fractional distillation. The question is then: how can we study low-vapor-pressure fuels in a shock tube? The solution presented here, which avoids the problems associated with heating, is called the aerosol shock tube. In the aerosol shock tube, the fuel is injected as an aerosol of micron-size droplets. Then a series of shock waves first evaporate the fuel and subsequently raise the resultant purely gas-phase mixture to combustion-relevant temperatures. With proper selection of the shock strength and timing, this process effectively decouples the mass and heat transfer processes associated with evaporation from the chemical mechanism of combustion. This enables the study of extremely low-volatility fuels, never before studied in a purely gas-phase form in a shock tube. The first application of this new facility was to measure the ignition delay time for many previously inaccessible fuels in the gas-phase. In this thesis, we have measured ignition delay times for the pure surrogate fuel components n-decane, n-dodecane, n-hexadecane, and methyl decanoate as well as for multi-component fuels such as JP-7 and multiple different blends of diesel fuel. Taken over a range of conditions, these measurements provide sensitive validation targets for their respective chemical mechanisms. These data showed agreement with past heated shock tube experiments for fuels in which premature fuel decomposition is not an issue (n-decane and low concentration n-dodecane). However, when comparing heated and aerosol shock tube ignition delay times for fuels that require significant heating, like n-hexadecane, the existing heated shock tube data demonstrated evidence of premature decomposition. The second application to the study of chemical kinetics was to measure the concentration of important species during the decomposition and oxidation of select low-vapor-pressure fuels. These species time-histories provide much more information for kinetic mechanism refinement. Experiments were performed to measure the important OH radical and the stable intermediate C2H4 for both n-hexadecane and diesel. The number of important low-vapor-pressure fuels that require high-quality validation targets is large, and our new method for providing this data has proven very effective. This work enables the development of the next generation of accurate chemical mechanisms and will be essential to their success.
Author: W. R. WARREN
Publisher:
ISBN:
Category :
Languages : en
Pages : 1
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Book Description
Progress in the development and evaluation of an electrically heate helium shock driven acility is described. The work covered is concerned primarily with a small prototype shock tube. while this tube does not completely meet the requirements one would establish for an ultimate test facility, results from its study do indicate that the attractive features of high performance shock tubes discussed earlier can be achieved. One interesting result of this work is that the prototype facility itself has been found to be useful in the study of hypervelocity stagnation region convective heat transfer problems. (Author).
Author: B. W. Taylor
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Jim J. Jones
Publisher:
ISBN:
Category : Aerodynamic heating
Languages : en
Pages : 22
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 23
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Book Description
We have developed a new aerosol loading technique to be used in shock tube measurements of combustion kinetics, in particular ignition times, of low-vapor pressure fuels. This technique provides a uniform spatial distribution of aerosol in the shock tube, which ensures well-behaved shock-induced flows and a narrow micron-sized aerosol size distribution that rapidly evaporates, thereby providing the capability to produce high-concentration vapor mixtures derived from a wide variety of fluids including low-vapor-pressure practical fuels and fuel surrogates. At present we utilize the incident shock wave to vaporize the fuel droplets, and the reflected shock wave to induce chemical reaction. We report here the first aerosol shock tube ignition delay time measurements of n-dodecane/O2/argon mixtures. These measurements are found to be consistent with those made in our heated shock tube facility.
Author: Charles E. Treanor
Publisher: State University of New York Press
ISBN: 1438405502
Category : Philosophy
Languages : en
Pages : 908
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Book Description
Sponsored by the U.S. Air Force Office of Scientific Research, this conference was held in Niagara Falls on July 6–9, 1981. This book includes material on the following topics: instrumentation and diagnostics, shock tube facilities and techniques, gas dynamic experiments, heat transfer and real gas effects, boundary layers, shock structure, shock propagation, laser and spectral optical studies, chem and kinetics, relaxation and excitation, ionization, dusty gases, two-phase flow and condensation, shock waves in the environment and energy, and energy-related processes. The book contains a total of 98 papers by well-known specialists.
Author: George T. Skinner
Publisher:
ISBN:
Category : Detectors
Languages : en
Pages : 78
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Book Description
The preliminary development of a high intensity molecular beam, in which a small tailored interface hypersonic shock-tunnel is used as the gas source, is reported. The aim is to extend molecular beam techniques into the 1-10 e.v. per particle range by utilizing the capability of the shock tube to generate high temperatures. A 0.7 e.v. nitrogen beam was produced in the pilot apparatus. The intensity of 2.5 x 10 to the 18th power molecules 1/sq.cm./sec. and the spreading angle of 6 deg agree with a theoretical analysis which takes into account attenuation caused by scattered molecules which have been thermally accommodated at the walls of the apparatus. A modified Kantrowitz-Grey system is used to obtain the high-energy beam.
Author: Alfred Gordon Gaydon
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 344
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Book Description
