Do liquid propellant rocket engines experience thrust oscillation?Are rocket exhaust flames ever opaque?Limiting factors of liquid rocket engine thrustDetonation Liquid rocket engineLiquid propellant stored as solidCould a “nuclear turbo-jet” be built?Is it possible to create different colors in rocket exhaust?
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Do liquid propellant rocket engines experience thrust oscillation?
Are rocket exhaust flames ever opaque?Limiting factors of liquid rocket engine thrustDetonation Liquid rocket engineLiquid propellant stored as solidCould a “nuclear turbo-jet” be built?Is it possible to create different colors in rocket exhaust?
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I know SRBs have a quite bit of thrust oscillation, and it's pretty much part and parcel of burning solid propellant. Do liquid-propellant engines experience something similar albeit at a much smaller magnitude? If so what is the main cause of this constant small variation in thrust level? Is it because of the combustion process inside the bell? In Falcon 9 launches you often see photos like this 
The streak patterns of the exhaust plume indicate there is at least some non-uniformity of the pressure and temperature field inside. I assume every liquid engine actually behaves like this, but it's only apparent on LOX/RP-1 engine because of soot acting like temperature indicator through the intensity of the glow for the pattern.
rockets exhaust
asked 8 hours ago
Meatball PrincessMeatball Princess
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$endgroup$
add a comment
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$begingroup$
I know SRBs have a quite bit of thrust oscillation, and it's pretty much part and parcel of burning solid propellant. Do liquid-propellant engines experience something similar albeit at a much smaller magnitude? If so what is the main cause of this constant small variation in thrust level? Is it because of the combustion process inside the bell? In Falcon 9 launches you often see photos like this
The streak patterns of the exhaust plume indicate there is at least some non-uniformity of the pressure and temperature field inside. I assume every liquid engine actually behaves like this, but it's only apparent on LOX/RP-1 engine because of soot acting like temperature indicator through the intensity of the glow for the pattern.
rockets exhaust
asked 8 hours ago
Meatball PrincessMeatball Princess
4901 silver badge10 bronze badges
$endgroup$
1
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I think the vertical streaking is closely related to the physical arrangement of the fuel/oxidizer injectors and resulting flow patterns, but I'm not sure why I think that.
$endgroup$
– Russell Borogove
7 hours ago
1
$begingroup$
Agreed, and if it was perfectly mixed, you likely wouldn't see the streaking.
$endgroup$
– Organic Marble
5 hours ago
add a comment
|
$begingroup$
I know SRBs have a quite bit of thrust oscillation, and it's pretty much part and parcel of burning solid propellant. Do liquid-propellant engines experience something similar albeit at a much smaller magnitude? If so what is the main cause of this constant small variation in thrust level? Is it because of the combustion process inside the bell? In Falcon 9 launches you often see photos like this
The streak patterns of the exhaust plume indicate there is at least some non-uniformity of the pressure and temperature field inside. I assume every liquid engine actually behaves like this, but it's only apparent on LOX/RP-1 engine because of soot acting like temperature indicator through the intensity of the glow for the pattern.
rockets exhaust
asked 8 hours ago
Meatball PrincessMeatball Princess
4901 silver badge10 bronze badges
$endgroup$
I know SRBs have a quite bit of thrust oscillation, and it's pretty much part and parcel of burning solid propellant. Do liquid-propellant engines experience something similar albeit at a much smaller magnitude? If so what is the main cause of this constant small variation in thrust level? Is it because of the combustion process inside the bell? In Falcon 9 launches you often see photos like this
The streak patterns of the exhaust plume indicate there is at least some non-uniformity of the pressure and temperature field inside. I assume every liquid engine actually behaves like this, but it's only apparent on LOX/RP-1 engine because of soot acting like temperature indicator through the intensity of the glow for the pattern.
rockets exhaust
rockets exhaust
asked 8 hours ago
Meatball PrincessMeatball Princess
4901 silver badge10 bronze badges
asked 8 hours ago
Meatball PrincessMeatball Princess
4901 silver badge10 bronze badges
asked 8 hours ago
Meatball PrincessMeatball Princess
4901 silver badge10 bronze badges
asked 8 hours ago
Meatball PrincessMeatball Princess
4901 silver badge10 bronze badges
asked 8 hours ago
Meatball PrincessMeatball Princess
4901 silver badge10 bronze badges
4901 silver badge10 bronze badges
1
$begingroup$
I think the vertical streaking is closely related to the physical arrangement of the fuel/oxidizer injectors and resulting flow patterns, but I'm not sure why I think that.
$endgroup$
– Russell Borogove
7 hours ago
1
$begingroup$
Agreed, and if it was perfectly mixed, you likely wouldn't see the streaking.
$endgroup$
– Organic Marble
5 hours ago
add a comment
|
1
$begingroup$
I think the vertical streaking is closely related to the physical arrangement of the fuel/oxidizer injectors and resulting flow patterns, but I'm not sure why I think that.
$endgroup$
– Russell Borogove
7 hours ago
1
$begingroup$
Agreed, and if it was perfectly mixed, you likely wouldn't see the streaking.
$endgroup$
– Organic Marble
5 hours ago
1
1
$begingroup$
I think the vertical streaking is closely related to the physical arrangement of the fuel/oxidizer injectors and resulting flow patterns, but I'm not sure why I think that.
$endgroup$
– Russell Borogove
7 hours ago
$begingroup$
I think the vertical streaking is closely related to the physical arrangement of the fuel/oxidizer injectors and resulting flow patterns, but I'm not sure why I think that.
$endgroup$
– Russell Borogove
7 hours ago
1
1
$begingroup$
Agreed, and if it was perfectly mixed, you likely wouldn't see the streaking.
$endgroup$
– Organic Marble
5 hours ago
$begingroup$
Agreed, and if it was perfectly mixed, you likely wouldn't see the streaking.
$endgroup$
– Organic Marble
5 hours ago
add a comment
|
1 Answer
1
active
oldest
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$begingroup$
Yes, in liquid engines this phenomenon is called "rough combustion".
Sutton (4th edition) says
Combustion that gives pressure fluctuations greater than about +/- 5%
of the mean pressure at a chamber wall location and which occur at
completely random intervals is called rough combustion.
It's different from "combustion instability" defined as activity which
displays organized oscillations ocurring at well-defined intervals
with a pressure peak that may be maintained, may increase, or may die
out.
pp. 257 - 259
The streak patterns you mention are more likely due to non-uniform mixing resulting in slight variations in local mixture ratio, than due to rough combustion, IMHO.
answered 8 hours ago
Organic MarbleOrganic Marble
79.2k4 gold badges235 silver badges338 bronze badges
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$begingroup$
Yes, in liquid engines this phenomenon is called "rough combustion".
Sutton (4th edition) says
Combustion that gives pressure fluctuations greater than about +/- 5%
of the mean pressure at a chamber wall location and which occur at
completely random intervals is called rough combustion.
It's different from "combustion instability" defined as activity which
displays organized oscillations ocurring at well-defined intervals
with a pressure peak that may be maintained, may increase, or may die
out.
pp. 257 - 259
The streak patterns you mention are more likely due to non-uniform mixing resulting in slight variations in local mixture ratio, than due to rough combustion, IMHO.
answered 8 hours ago
Organic MarbleOrganic Marble
79.2k4 gold badges235 silver badges338 bronze badges
$endgroup$
add a comment
|
$begingroup$
Yes, in liquid engines this phenomenon is called "rough combustion".
Sutton (4th edition) says
Combustion that gives pressure fluctuations greater than about +/- 5%
of the mean pressure at a chamber wall location and which occur at
completely random intervals is called rough combustion.
It's different from "combustion instability" defined as activity which
displays organized oscillations ocurring at well-defined intervals
with a pressure peak that may be maintained, may increase, or may die
out.
pp. 257 - 259
The streak patterns you mention are more likely due to non-uniform mixing resulting in slight variations in local mixture ratio, than due to rough combustion, IMHO.
answered 8 hours ago
Organic MarbleOrganic Marble
79.2k4 gold badges235 silver badges338 bronze badges
$endgroup$
add a comment
|
$begingroup$
Yes, in liquid engines this phenomenon is called "rough combustion".
Sutton (4th edition) says
Combustion that gives pressure fluctuations greater than about +/- 5%
of the mean pressure at a chamber wall location and which occur at
completely random intervals is called rough combustion.
It's different from "combustion instability" defined as activity which
displays organized oscillations ocurring at well-defined intervals
with a pressure peak that may be maintained, may increase, or may die
out.
pp. 257 - 259
The streak patterns you mention are more likely due to non-uniform mixing resulting in slight variations in local mixture ratio, than due to rough combustion, IMHO.
answered 8 hours ago
Organic MarbleOrganic Marble
79.2k4 gold badges235 silver badges338 bronze badges
$endgroup$
Yes, in liquid engines this phenomenon is called "rough combustion".
Sutton (4th edition) says
Combustion that gives pressure fluctuations greater than about +/- 5%
of the mean pressure at a chamber wall location and which occur at
completely random intervals is called rough combustion.
It's different from "combustion instability" defined as activity which
displays organized oscillations ocurring at well-defined intervals
with a pressure peak that may be maintained, may increase, or may die
out.
pp. 257 - 259
The streak patterns you mention are more likely due to non-uniform mixing resulting in slight variations in local mixture ratio, than due to rough combustion, IMHO.
answered 8 hours ago
Organic MarbleOrganic Marble
79.2k4 gold badges235 silver badges338 bronze badges
edited 7 hours ago
answered 8 hours ago
Organic MarbleOrganic Marble
79.2k4 gold badges235 silver badges338 bronze badges
answered 8 hours ago
Organic MarbleOrganic Marble
79.2k4 gold badges235 silver badges338 bronze badges
answered 8 hours ago
Organic MarbleOrganic Marble
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79.2k4 gold badges235 silver badges338 bronze badges
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$begingroup$
I think the vertical streaking is closely related to the physical arrangement of the fuel/oxidizer injectors and resulting flow patterns, but I'm not sure why I think that.
$endgroup$
– Russell Borogove
7 hours ago
1
$begingroup$
Agreed, and if it was perfectly mixed, you likely wouldn't see the streaking.
$endgroup$
– Organic Marble
5 hours ago