DETONABILITY OF FUEL-AIR MIXTURES IN TERMS OF DEFLAGRATION-TO-DETONATION TRANSITION

A new experimental method for evaluating the detonability of fuel-air mixtures (FAMs) based on measuring the deflagration-to-detonation (DDT) run-up distance and/or time in a standard pulse detonation tube is used to rank gaseous premixed and nonpremixed FAMs by their detonability under substantially identical thermodynamic and gasdynamic conditions. In the experiments, FAMs based on hydrogen, acetylene, ethylene, propylene, propane-butane, n-pentane, and natural gas of various compositions, as well as FAMs based on the gaseous pyrolysis products of polyethylene (PE) and polypropylene (PP) are used: from extremely fuel-lean to extremely fuel-rich at normal temperatures and pressures.

Download Full-text

Deflagration-to-detonation transition in air mixtures of polypropylene pyrolysis products

Доклады Академии наук ◽

10.31857/s0869-56524882162-166 ◽

2019 ◽

Vol 488 (2) ◽

pp. 162-166

Author(s):

S. M. Frolov ◽

V. I. Zvegintsev ◽

V. S. Aksenov ◽

I. V. Bilera ◽

M. V. Kazachenko ◽

...

Keyword(s):

Decomposition Temperature ◽

Stoichiometric Mixture ◽

Gas Generator ◽

Pyrolysis Products ◽

Deflagration To Detonation Transition ◽

Pulsed Detonation ◽

Hydrocarbon Gas ◽

Detonation Transition ◽

Run Up ◽

Propane Butane

A new method for determining the detonability of fuel is proposed based on the measured values of the detonation run-up distance and time in the standard pulsed detonation tube (PDT). Granulated polypropylene (GP) was used as a fuel. A test bench with the PDT and a gas generator was designed and manufactured for the preparation of the GP pyrolysis products at a decomposition temperature of up to 800 °C. Experiments on deflagration-to-detonation transition in air mixtures of pyrolysis products of the GP showed that such mixtures exhibit detonability close to that of liquefied hydrocarbon gas (LPG) of the propane-butane automobile brand in a stoichiometric mixture with air under normal conditions.

Download Full-text

Experimental investigation on multi-cycle two-phase spiral pulse detonation tube of two configurations

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410018817455 ◽

2018 ◽

Vol 233 (11) ◽

pp. 4166-4175

Author(s):

Hua Qiu ◽

Zheng Su ◽

Cha Xiong

Keyword(s):

Pressure Waves ◽

Propagation Characteristics ◽

Transient Pressure ◽

Two Phase ◽

Pulse Detonation ◽

Compression Waves ◽

Detonation Tube ◽

Deflagration To Detonation Transition ◽

Pulsed Detonation ◽

Detonation Transition

The spiral tube structure is an effective method to shorten the axial length of the pulse detonation chamber. In this article, spiral pulsed detonation tube with two kinds of spiral configuration was experimentally investigated. Liquid gasoline and air were used as fuel and oxidant, respectively, and equivalence ratios were controlled to about 1.0. Based on the transient pressure along the tube, the propagation characteristics of the pressure waves in the multi-cycle spiral pulsed detonation tubes, such as pressure peaks, wave velocities and propagation process, were analyzed. Results showed that propagation of double compression waves was the common feature during the process of deflagration to detonation transition in the presented spiral tubes, and the onset of detonation was initiated by a local explosion in the second compression wave. The deflagration to detonation transition characteristics with detonation initiation and combustion characteristics without initiation in the spiral sections were both related to the dimensionless distance. Propagation characteristics of the pressure waves were influenced by the use of different spiral configuration. And some interesting phenomena were also found.

Download Full-text

Computational Study of Deflagration to Detonation Transition in Pulse Detonation Engine Using Shchelkin Spiral

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.772.136 ◽

2015 ◽

Vol 772 ◽

pp. 136-140 ◽

Cited By ~ 1

Author(s):

Pinku Debnath ◽

Krishna Murari Pandey

Keyword(s):

Combustion Wave ◽

Computational Study ◽

Pulse Detonation Engine ◽

Flame Velocity ◽

Pulse Detonation ◽

Detonation Tube ◽

Deflagration To Detonation Transition ◽

Contour Plots ◽

Detonation Engine ◽

Detonation Transition

Detonation combustion wave is much more energetic combustion process in pulse detonation engine combustion system. Numerous experimental, theoretical and numerical analyses have been studied in pulse detonation engine to implement in practical propulsion system. In this present computational study the simulation was carried out for deflagration flame acceleration and deflagration to detonation transition of hydrogen air combustible mixture inside the detonation tube with and without Shchelkin spiral. A three dimensional computational analysis has been done by finite volume discretization method using ANSYS Fluent 14 CFD commercial software. The LES turbulence model with second order upwind discretization scheme was adopted with standard boundary conditions for unsteady combustion wave simulations. From the computational study it was found that intensity of detonation wave velocity and dynamic pressure is higher near to the boundary of Shchelkin spiral in detonation tube. The contour plots comparisons clearly show that deflagration flame accelerates in detonation tube as present of Shchelkin spiral. The contour plots also suggest that deflagration flame velocity and pressure are less in without Shchelkin spiral in detonation tube. The accelerating detonation waves are approximately near about Chapment-Jouguet values in detonation tube with Shchelkin spiral.

Download Full-text

DEFLAGRATION-TO-DETONATION TRANSITION IN A STRATIFIED SYSTEM “GASEOUS OXYGEN-LIQUID FILM OF N-DECANE”

NONEQUILIBRIUM PROCESSES. Vol. 2. Fundamentals of combustion ◽

10.30826/nepcap2018-2-30 ◽

2020 ◽

Author(s):

S. M. FROLOV ◽

◽

V. S. AKSENOV ◽

I. O. SHAMSHIN ◽

◽

...

Keyword(s):

Liquid Film ◽

Ignition Source ◽

Gaseous Oxygen ◽

Deflagration To Detonation Transition ◽

Operation Process ◽

Continuous Detonation ◽

Smooth Channel ◽

Detonation Transition ◽

Run Up ◽

X 24

Deflagration-to-detonation transition (DDT) in the system “gaseous oxygen- liquid film of n-decane” ' with a weak ignition source was obtained experimentally. In a series of experiments with ignition by an exploding wire that generates a weak primary shock wave (SW) with a Mach number ranging from 1.03 to 1.4, the DDT with the detonation run-up distances 1 to 4 m from the ignition source and run-up time 3 ms to 1.7 s after ignition was observed in a straight smooth channel of rectangular 54 x 24-millimeter cross section, 3 and 6 m in length with one open end. The DDT is obtained for relatively thick films with a thickness of 0. 3-0.5 mm, which corresponds to very high values of the overall fuel-to-oxygen equivalence ratios of 20-40. The registered velocity of the detonation wave (DW) was 1400-1700 m/s. In a number of experiments, a high-velocity quasi-stationary detonation-like combustion front was recorded running at an average velocity of 700-1100 m/s. Its structure includes the leading SW followed by the reaction zone with a time delay of 90 to 190 s. The obtained results are important for the organization of the operation process in advanced continuous-detonation and pulsed-detonation combustors of rocket and air-breathing engines with the supply of liquid fuel in the form of a wall film.

Download Full-text