Pulse jets and ram jets as part of my course on jet propulsion

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Discussion Overview

The discussion revolves around the concepts of pulse jets and ram jets, specifically focusing on the term "aero-thermo-dynamic-ducts" as it relates to these types of jet propulsion systems. Participants seek clarification on the terminology and the operational principles of these engines.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant expresses confusion about the term "aero-thermo-dynamic-ducts" and requests an explanation.
  • Another participant suggests that the term implies a tube where work is extracted from hot air, although they have not encountered the term before.
  • A participant provides a basic overview of how pulse jets and ram jets operate, noting that both types ingest air, mix it with fuel, and expel exhaust for thrust, while highlighting the differences in their combustion processes.
  • There is a suggestion that the term may indicate the absence of rotating components in these engines, with a focus on their duct-like structure.
  • A reference is made to aerothermodynamics as the study area for components in high-speed turbomachinery, with a note that the term "aerothermodynamic duct" was coined for ram jets.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the term "aero-thermo-dynamic-ducts," with some expressing uncertainty about its meaning and others offering interpretations. The discussion remains unresolved regarding the clarity and usage of the term.

Contextual Notes

Participants acknowledge the vagueness of the term and its implications, but there are no definitive explanations or agreements on its meaning or application in the context of pulse jets and ram jets.

banerjeerupak
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i was reading about pulse jets and ram jets as part of my course on jet propulsion. all i was told was that they are aero-thermo-dynamic-ducts.

couldn't understand what they mean. checked google, but the articles i got were vague.

could someone explain what aero-thermo-dynamic-ducts are?
 
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I've never heard that term. Going by the words involved, it should simply mean that it's a tube of some sort in which work is extracted from hot air.
 
then could you tell me if that is the way in which pulse jets and ram jets work?
 
I'm not the expert here; Fred Garvin, Russ Watters, Rainman Aero, Astronuc, and a few others know far more than I could ever learn. I'm sure that one or more of them will weigh in before long.
That having been said, the basic answer is 'yes'.
Both types of engines ingest air without the aid of a compressor system, mix it with fuel, burn the mix, and expel the exhaust to provide thrust. The difference is that a pulse jet uses a valve box at the front, or a carefully tuned tube, to prevent the exhaust from going that way, which opens for intake and closes for combustion. That cyclic open/close/boom is why it pulses. A ramjet carries out continuous combustion, but it has to be moving at something on the order of 400mph to work.
By the way, if you're taking a course on this, shouldn't they be teaching you how they work?
 
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I've never heard the term either, but what it implies to me is that both aerodynamic and thermodynamic principles are at work. Sounds reasonable, but yes, vague...
 
I am assuming, by the description, that the original term was meant to mean that in both ramjets and pulse jets, there are no rotating components. Hence the "ducts" reference because they are really just tubes doing the work.

Aerothermodynamics is the general area of study for the components and systems in turbomachinery (usually high speeds).

According to this web site, aerothermodynamic duct was coined by the Brits for a ram jet.

http://www.onera.fr/conferences-en/ramjet-scramjet-pde/
 
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