Khristianovich Institute of Theoretical and Applied Mechanics SB RAS Influence of Pulse Energy Deposition on Burning Development in the Channel ВЛИЯНИЕ ИМПУЛЬСНОГО ЭНЕРГЕТИЧЕСКОГО ВОЗДЕЙСТВИЯ НА РАЗВИТИЕ ГОРЕНИЯ В КАНАЛЕ V. A. Zabaykin, P. K. Tretyakov 7 th International Seminar on Flame Structure, July 11 -15 2011, Novosibirsk
Problems of Burning in Channels at Supersonic Flow Speed In channels at flow Mach numbers above 1. 5 the transition from a supersonic current to the subsonic one occurs in system of (direct, oblique, λ-shaped) shock waves. The arising complex wave structure is called a pseudo-shock. Such type of a current exists in gasdynamic lasers, supersonic wind tunnels and combustion chambers of scramjets. In the latter case the organization of burning in pseudo-shock leads to an intensification of mixing processes and raises intensity of burning. However, a control of pseudo-shock seems to involve considerable difficulties. In the report the new approach based on non-stationary influence on pseudo-shock is shown.
Experimental Facility (Supersonic Combustion Wind Tunnel with Arc Heater) M=1– 3 T 0 = 1200 -2700 K W = 2 000 KWt τ = 10 ÷ 100 s
Pseudoshock Structure Р=0. 18 MPa Р=0. 20 MPa Р=0. 22 MPa Р=0. 24 MPa 1 – поток (air flow) 2 – система скачков (shock train) 3 – область смешения (mixing region) 4 – область псевдоскачка (pseudoshock) 5 – распределение статического давления по оси (pressure on axis) 6 – распределение статического давления по стенке канала (wall pressure) Р=0. 26 MPa Shlieren images, P - var Shlieren images of stationary positions of pseudoshock
Constant Area Channel Канал постоянного сечения Foto Scheme of Flat Channel of Constant Cross-Section Схема плоского канала постоянного сечения ( 20× 40× 565 mm ) 1 – nozzle М=2; 2 – quartz windows 20 × 150 mm
The Applied Ways of Periodic Influence Mechanical Overlapped area of duct outlet Thermogasdynamic The oscillogram of work of pulse-periodic plasmatron
Pseudo-shock Movement at External Periodic Influence The experiment scheme : 1 – nozzle М=2; 2 – channel with registration area; 3 – locations of pulse-periodic plasma input. Flat channel 40× 20× 565 mm, throttling – mechanical or by a pulsed plasmatron Frequency of influence f = 25 Hz Videorecording: slow motion playback. Without influence Maximum displacement Maximum re-entry
Experiments in the Axisymmetric Channel of Constant and Variable Section, an Isothermal Stream The scheme of the axisymmetric channel of constant section ( d = 50 mm, L = 550 mm) 1 – Tepler instrument IAB-451; 2 – mechanical choke; 3 – CCD-camera.
Refinement on dynamics of movement of pseudo-shock and possibility of its registration in the axisymmetric channel Possibility of exact registration of pseudo-jump movement speed in axisymmetric channel by optical methods with the limited possibilities of registration is shown Look of the central part of pseudo-jump in the cylindrical channel It is found out that at periodic disturbances the movement rate of gasdynamic structures isn't a constant and has a maximum at 3 -4 ms after a start of motion а b Speed of movement of pseudo-shock upwards (a) and downwards (b) on the axisymmetric channel at throttling frequency 12. 2 Hz. Speed of moving of pseudo-shock isn't a constant, and has a maximum in a middle part of a cycle
Experiments in the Axisymmetric Channel of Constant and Variable Section, a High-Temperature Stream, Hydrogen Burning The axisymmetric channel of constant section d = 50 mm Cooled nozzle М=2 with a hydrogen injector The channel of variable section: 1 – nozzle, 2 – channel D=50 mm, 3 – expanding section, 4 – channel D=90 mm, 5 – exhaust system. Flame look in channel windows at hydrogen burning
Diffusive and pseudo-shock burning modes in the combined channel The channel with сonstant and expansion sections The power impulse shifts a diffusive mode of burning into pseudo-shock one Diffusive mode Power delivery point Distribution of pressure and OH radiation for two modes of burning Pseudo-shock mode
Conclusions - Periodic power influence on an isothermal air stream in the channel leads to pseudo-shock moving up and down the stream; - Speed of moving of pseudo-shock in an isothermal stream in axisymmetric and rectangular channels at input of periodic disturbances is determined; its value falls within the limits of 5 -25 m/s. At the organization of burning the speed of pseudo-shock decreases down to 1 -2 m/s; - At periodic input of disturbances the speed of movement of gasdynamic structures isn't constant, and has a maximum at 3 -4 ms after a start of motion; - It is experimentally established that for a mode with diffusive H 2 burning a short-term power impulse supply into a stream leads to a pseudo-shock burning mode.
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