scholarly journals Chemical Reaction in a Shock Wave. I. The Ignition Delay of a Hydrogen-Oxygen Mixture in a Shock Tube

1963 ◽  
Vol 36 (10) ◽  
pp. 1233-1236 ◽  
Author(s):  
Shiro Fujimoto
Keyword(s):  
Shock Wave ◽  
Shock Tube ◽  
Chemical Reaction ◽  
Ignition Delay ◽  
Oxygen Mixture

Ignition and Combustion of Heavy Hydrocarbons Using an Aerosol Shock-Tube Approach

2010 ◽  
Author(s):  
Brandon Rotavera ◽  
Nolan Polley ◽  
Eric L. Petersen ◽  
Kara Scheu ◽  
Mark Crofton ◽  
...  
Keyword(s):  
Shock Wave ◽  
Vapor Pressure ◽  
Shock Tube ◽  
Gas Phase ◽  
Ignition Delay ◽  
Two Phase ◽  
Heavy Hydrocarbons ◽  
Gaseous Oxidizer ◽  
Ignition Delay Times ◽  
Delay Times

Results from a heterogeneous shock-tube approach recently demonstrated at Texas A&M University, wherein a hydrocarbon fuel is introduced in liquid phase with gaseous oxidizer, are presented. The shock tube has been designed for controlled measurement of ignition delay times, sooting phenomena, radical species concentrations, time-dependent species profiles, and nanoparticle-aided combustion using heavy hydrocarbons which are difficult to study using the traditional shock tube approach. Aerosol is generated in a high-vacuum manifold positioned 4-m from the endwall where optical and pressure-based diagnostics are stationed. The approach reduces the propensity for fuel-film deposition near the endwall avoiding optical and/or kinetic disturbances that could result. The aerosol enters the shock tube initially as a two-phase flow of liquid fuel and gaseous oxidizer/inert gas. Liquid droplets partially evaporate while resident in the shock tube, prior to shock wave generation, and are then completely vaporized behind the incident shock wave. Behind the reflected shock wave, then, resides a pure gas-phase fuel and oxidizer mixture. The primary benefit of the aerosol shock tube approach is the ability to inject fuels of low vapor pressure at high or low concentrations. The classic shock-tube approach introduces gas-phase constituents only, and has difficulty accommodating low vapor-pressure liquids, except when component partial pressures are much lower than what is usually required. In the present work, n-heptane aerosol (C7H16, Pvap, 20 °C ∼ 35 torr), was generated with O2/Ar carrier gas and dispersed in the shock tube in a uniform manner. Stoichiometric ignition delay times with temperature varied from 1240 K to 1600 K and pressure maintained near 2.0 atm are compared to gas-phase data at similar conditions and a chemical kinetic model for heptane combustion. Excellent agreement was found between the two-phase aerosol approach and the classical method involving vapor-phase n-heptane and pre-mixed gases. The measured activation energy for the stoichiometric mixture at 2.0 atm (EA = 42.3 kcal /mol), obtained with the two-phase technique, compares well with the literature value.

Simulation of Interaction between a Spherical Shock Wave and a Layer of Granular Material in a Conical Shock Tube

2021 ◽  
Vol 15 (4) ◽  
pp. 685-690
Author(s):  
S. V. Khomik ◽  
I. V. Guk ◽  
A. N. Ivantsov ◽  
S. P. Medvedev ◽  
E. K. Anderzhanov ◽  
...  
Keyword(s):  
Shock Wave ◽  
Granular Material ◽  
Shock Tube ◽  
Spherical Shock Wave ◽  
Conical Shock ◽  
Spherical Shock

Shock Tube Simulation of the Transient Surge Phase Inside an Axial Compressor

2018 ◽  
Author(s):  
Paul Xiubao Huang ◽  
Robert S. Mazzawy
Keyword(s):  
Shock Wave ◽  
Shock Tube ◽  
High Speed ◽  
Transient Flow ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Dynamic Effect ◽  
Initiation Site ◽  
Flow Reversal ◽  
Expansion Waves

This paper is a continuing work from one author on the same topic of the transient aerodynamics during compressor stall/surge using a shock tube analogy by Huang [1, 2]. As observed by Mazzawy [3] for the high-speed high-pressure (HSHP) ratio compressors of the modern aero-engines, surge is an event characterized with the stoppage and reversal of engine flow within a matter of milliseconds. This large flow transient is accomplished through a pair of internally generated shock waves and expansion waves of high strength. The final results are often dramatic with a loud bang followed by the spewing out of flames from both the engine intake and exhaust, potentially damaging to the engine structure [3]. It has been demonstrated in the previous investigations by Marshall [4] and Huang [2] that the transient flow reversal phase of a surge cycle can be approximated by the shock tube analogy in understanding its generation mechanism and correlating the shock wave strength as a function of the pre-surge compressor pressure ratio. Kurkov [5] and Evans [8] used a guillotine analogy to estimate the inlet overpressure associated with the sudden flow stoppage associated with surge. This paper will expand the progressive surge model established by the shock tube analogy in [2] by including the dynamic effect of airflow stoppage using an “integrated-flow” sequential guillotine/shock tube model. It further investigates the surge formation (characterized by flow reversal) and propagation patterns (characterized by surge shock and expansion waves) after its generation at different locations inside a compressor. Calculations are conducted for a 12-stage compressor using this model under various surge onset stages and compared with previous experimental data [3]. The results demonstrate that the “integrated-flow” model closely replicates the fast moving surge shock wave overpressure from the stall initiation site to the compressor inlet.

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