Numerical investigation of three deflagration-to-detonation transition conditions related to the velocity of the spontaneous reaction wave

Pada sistem pembakaran snpersonik, shock wave dan reaction wave merambat dengan kondisi berhimpit dengan kecepatan di bawah 1 mikro detik. Shock wave yang memiliki tekanan tinggi hingga mencapai 20 kali tekanan awal akan membahayakan bagi keselamatan manusia jika kecelakaan detonasi terjadi. Dengan demikian diharapkan kecelakaan yang diakibatkan oleh gelombang detonasi akan dapat dihindari atau diminimalisasi. Hal ini dilakukan dengan cara mengubah gelombang detonasi menjadi gelombang deflagrasi, yaitu memisahkan shock wave dengan reaction wave akibat proses ekspansi gelombang detonasi. Pada eksperimen ini, model diuji pada pipa uji detonasi (PUD) horizontal berpenampang lingkaran dengan diameter dalam 50 mm dan panjang 6300 mm yang terdiri dari seksi driver sepanjang 1000 mm, seksi driven sepanjang 5300 mm. Pada seksi driven dipasang model facing step 50% dengan bahan alumunium sepanjang 300 mm. Empat unit sensor tekanan yang berfungsi untuk merekam profil tekanan sepanjang proses pembakaran dan empat unit ionisation probe yang berfungsi untuk mendeteksi waktu kedatangan flame front, dipasang masing - masing 2 unit di upstream dan 2 unit di downstream dari model dengan posisi saling berhadapan. Campuran bahan bakar untuk seksi driver yang digunakan pada eksperimen ini adalah campuran hidrogen dan oksigen dengan kondisi stokiometrik dan tekanan awal 100 kPa untuk menjamin terjadinya detonasi pada seksi driver, sedangkan pada seksi driven campuran bahan bakar yang digunakan adalah campuran hidrogen - oksigen dengan diluent argon pada variasi tekanan awal mulai 20 kPa hingga 100 kPa. Dari hasil penelitian diperoleh 3 mekanisme perambatan gelombang detonasi di belakang model.facing step 50%, yaitu a) Reinisiasi detonasi oleh adanya DDT, yaitu kondisi merambatnya kembali gelombang detonasi akibat proses deflagration to detonation transition di daerah downstream dari model setelah sebelumnya quenching detonasi akibat gelombang ekspansi, (b) Reinisiasi detonasi oleh adanya S-W, kondisi merambatnya kembali gelombang detonasi akibat adanya interaksi gelonbang kejut dengan dinding pipa, (c) transmisi detonasi, merupakan proses perambatan gelombang detonasi tanpa melalui proses quenching didaerah downstream dari model.

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RANKING OF FUEL-AIR MIXTURES IN TERMS OF THEIR PROPENSITYTO DEFLAGRATION-TO-DETONATION TRANSITION

PROGRESS IN DETONATION RESEARCH ◽

10.30826/icpcd12a05 ◽

2020 ◽

Author(s):

S. M. FROLOV ◽

◽

V. I. ZVEGINTSEV ◽

V. S. AKSENOV ◽

I. V. BILERA ◽

...

Keyword(s):

Detonation Wave ◽

The Other ◽

Practical Application ◽

Deflagration To Detonation Transition ◽

Other Hand ◽

Pressure Gain Combustion ◽

Reactive Mixture ◽

Detonation Transition ◽

The One ◽

Energy Converting

The term "detonability" with respect to fuel-air mixtures (FAMs) implies the ability of a reactive mixture of a given composition to support the propagation of a stationary detonation wave in various thermodynamic and gasdynamic conditions. The detonability of FAMs, on the one hand, determines their explosion hazards during storage, transportation, and use in various sectors of the economy and, on the other hand, the possibility of their practical application in advanced energy-converting devices operating on detonative pressure gain combustion.

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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.

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Flame Speed and Deflagration-Detonation Analysis in Flare Stack and Header

Volume 2: Development and Applications in Computational Fluid Dynamics; Industrial and Environmental Applications of Fluid Mechanics; Fluid Measurement and Instrumentation; Cavitation and Phase Change ◽

10.1115/fedsm2018-83445 ◽

2018 ◽

Author(s):

Philip Diwakar ◽

Jaleel Valappil

Keyword(s):

Ambient Air ◽

Flame Speed ◽

Safety Concerns ◽

Deflagration To Detonation Transition ◽

Detonation Transition

This paper examines safety concerns related to flame speeds when warm relief gas snuffs out the pilot at the flare stack and pulls in ambient air and a spark ignites the vapor in the header. The flame speed essentially determines if the propagating flame speed is a deflagration or a detonation based on whether its subsonic or supersonic. While pipes are sized for deflagrations, they need to be analyzed and tested for detonation pressures and temperatures. Transient CFD calculations help determine the flame speeds, deflagration to detonation transition, pressures and temperatures are compared to pipe specifications and help determine if a detonation leads to a Loss of Containment and suggests mitigations.

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