Структура течения в плоском комбинированном канале в

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
7th 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
T0 = 1200-2700 K
W = 2 000 KWt
τ = 10 ÷ 100 s
Pseudoshock Structure
Р=0.18MPa
Р=0.20MPa
Р=0.22MPa
Р=0.24MPa
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=0.26MPa
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=50mm, 3 – expanding section, 4 – channel
D=90mm, 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 H2 burning a
short-term power impulse supply into a stream leads to a pseudo-shock
burning mode.