Effects of hypersonic speed on the behaviour of normal shocks

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Discussion Overview

The discussion revolves around the behavior of normal shocks in hypersonic flow, particularly focusing on the effects of high Mach numbers and the potential interactions with oblique shocks. Participants explore the theoretical implications and physical phenomena associated with these conditions.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions the existence of normal shocks at hypersonic speeds, suggesting a lack of information on the topic.
  • Another participant presents an image related to shock wave interactions but does not clarify its relevance to normal shocks specifically.
  • A different participant asserts that normal shocks continue to follow established rules regardless of Mach number, noting that their behavior is distinct from oblique shocks due to the absence of body attachment.
  • There is a query about the role of molecular dissociation at high energies and whether it affects gas species or quantities across the shock.
  • One participant indicates that the occurrence of hypersonic conditions can vary based on Mach number and ambient conditions, suggesting a dependency on these factors.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of normal shocks at hypersonic speeds, with no consensus reached on the implications of molecular dissociation or the relevance of ambient conditions.

Contextual Notes

Some assumptions regarding the behavior of normal shocks and the conditions under which they operate remain unaddressed, particularly concerning the influence of boundary layers and viscous effects.

theudster
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TL;DR
What happens to normal shocks at hypersonic speed
I am learning about hypersonic flow now and there seems to be a lot of discussion about the effects on oblique shock as the Mach tends to be very large.
I was wondering what happens to the normal shock as the Mach number tends to be high and I can't seem to find anything about it. Is it because it is not possible to have a normal shock at hypersonic speeds?
 
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You don't find much on it because nothing happens. They still obey all of the same rules they did before, and since they aren't attached to a body, you don't have some of the fun interactions you can get with oblique shocks.

For that matter, so do oblique shocks. The issue is just that oblique shocks tend to get so close to the surfaces generating them that the effect of the boundary layer can no longer be ignored and the inviscid approximation typically used for supersonic flows breaks down. This is called either the viscous-inviscid interaction or the hypersonic viscous interaction.
 
Does anything interesting happen with regards to molecular dissociation actually changing the gas quantity/species through the shock or anything like that, or is the energy still not quite high enough for that?
 
It sure can but it all depends on Mach number and ambient conditions. You can be hypersonics with or without that.
 

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