Talk:Hypersonic wind tunnel

This article has a few spelling errors and some awkward grammar. E. Sn0 =31337= 13:00, 9 March 2006 (UTC)

Why didn't you edit it then instead of just adding a tag?Richyard 14:25, 13 September 2006 (UTC)

I fixed a spelling error and removed the tag. Gfloner 07:25, 18 February 2007 (UTC)

Pressure required 3GPa ?
It is stated "Simulations of a flow at 5.5 km/s, 45 km altitude would require tunnel temperatures of as much as 9000 K, and a pressure of 3 GPa.". I think that a pressure of 3 GPa (30 000 atmospheres!!!) is far too high, instead 3 MPa is more realistic (see further sections of the article). Also some quick calculations (adiabatic expansion) show that 9000K and 3MPa is more feasible. Any experts around? Regards NickFr (talk) 20:34, 30 December 2007 (UTC)

Considering the base of the Stratopause from International_Standard_Atmosphere, we have T=270.65K, p = 110.91Pa. Here, a = 329.71, hence M=16.68. Looking at a compressible flow table, at M=16.68, we have T/T0 = 0.1765e-1, p/p0 = 0.7311e-6, giving reservoir conditions of T=15300K, p = 151MPa assuming not heating of the flow. Assuming the flow is only heated in the subsonic region, at M=1, we have T/T0 = 0.8333, p/p0 = 0.5283, giving conditions immediately at the nozzle throat as T=12800K, p = 79.8MPa. The practicality of heating the flow in the supersonic region is not known. Additionally, the above all assumes that the working fluid is a perfect gas, which is a poor assumption at substantially elevated temperatures. — Preceding unsigned comment added by 88.97.163.220 (talk) 15:40, 12 August 2011 (UTC)

The high total pressure required, 3GPa, is required because of the need to reproduce the binary scaling parameter and Reynolds number in the wind tunnel. The binary scaling parameter is the product of density and length scale. This parameter arises from the the desire to reproduce the binary (two-body) dissociation reactions that are typically encountered in hypervelocity flight. 3GPa may seem like an unreasonable total pressure, but reflected-shock tunnels and expansion tunnels are capable (or nearly capable) of these pressure because they are impulse, or ultra short test duration facilities. — Preceding unsigned comment added by 68.192.183.239 (talk) 18:31, 8 February 2014 (UTC)

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