Evacuation-induced pressure differentials in multilayer insulation systems

Glassford, A. P. M.

doi:10.2514/3.7750

Cited by 1 publication

(3 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the case of an MLI, this load could even tear the insulation layers. 2 As can be drawn from the preceding discussion,the driving parameter is K , the ratio of characteristic times.…”

Section: K T C T P V Sa I T Pmentioning

confidence: 99%

“…Especially sensitive to pressure loading are multilayer insulations (MLIs) because they can de ect permanentlyor even tear. 2 Thus, typical spacecraftquali cationprocedures includethe determinationof integrity against pressure loads by either calculations or tests.…”

Section: Introductionmentioning

confidence: 99%

“…(2)(3)(4) into Eq. (1) with the condition P h P e yields the equation describing the evolution of the density in the reservoir…”

mentioning

confidence: 99%

See 2 more Smart Citations

Spacecraft Launch Depressurization Loads

Sanz-Andrés

Santiago-Prowald

Ayuso-Barea

1997

Journal of Spacecraft and Rockets

View full text Add to dashboard Cite

The pressure variation inside the launch vehicle fairing during climb through the atmosphere induces structural loads on the walls of closed-type spacecrafts or equipment boxes. If the evacuation of the air is not fast enough, excessive pressure loading can result in damage of elements exposed to the rising pressure jump, which depends mainly on the geometry of venting holes, the effective volume of air to be evacuated, and the characteristic time of pressure variation under the fairing. A theoretical study of the reservoir discharge forced by the fairing timedependent pressure variation is presented. The basic mathematical model developed can yield both a numerical solution for the pressure jump and an asymptotic solution for the most relevant case, the small-pressure-jump limit, showing the dependence on a single nondimensional parameter: the ratio of the reservoir discharge to the fairing pressure pro le characteristic times. The asymptotic solution validity range upper limit, obtained by comparison with the numerical solution, is determined by the starting of choked operation. Very high sensitivity of the maximum pressure jump to the ratio of characteristic times has been observed. Another relevant nding is that the pressure pro les for different launchers can be considered similar when rewritten in appropriate form and only their characteristic times are required for the analysis. The simple expressions of the asymptotic solution are a useful tool for preliminarily sizing the reservoir discharge geometry and estimating depressurization loads. Nomenclaturea h = speed of sound at the output section, m/s K = ratio of characteristic times, t c t p M h = Mach number at the output section n = polytropic coef cient P = static pressure, Pa P b = value of P e for choking of the ow, Pa P e = static pressure under the fairing, Pa p = dimensionless pressure in the reservoir, P 0 P i p 1 = rst term in the series expansion of S = effective hole output section area, m 2 T = dimensionless time, t t c T max t max = values of T and t at which a reaches its maximum value t = time, s t c = characteristic venting time, 2 V S A i , s t p = characteristic fairing pressure variation time, s U h = ow mean speed through the hole at the output section, m/s V = reservoir effective volume of air to be evacuated, m 3 = ratio of speci c heats P = pressure jump, P 0 P e , Pa a n = dimensionless pressure jump, asymptotic solution, and numerical solution max = maximum value of a = small parameter of series expansions = total pressure loss coef cient through the hole = instantaneousdimensionless density inside the reservoir, 0 i x = uid density at position x, kg/m 3 Subscripts e = instantaneousconditions inside the fairing h = instantaneousconditions at the reservoir hole exit i = initial conditions in the reservoir 0 = instantaneousreservoir conditions

show abstract

“…In the case of an MLI, this load could even tear the insulation layers. 2 As can be drawn from the preceding discussion,the driving parameter is K , the ratio of characteristic times.…”

Section: K T C T P V Sa I T Pmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%