Space shuttle based microgravity smoldering combustion experiments

Walther, David C.; Fernandez‐Pello, A. C.; Urban, David L.

doi:10.1016/s0010-2180(98)00095-9

Cited by 41 publications

(16 citation statements)

References 27 publications

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“…These values are shown and compared to other values in the literature in Table 3. These results are similar to those of Torero et al [9] and Walther et al [10], although since they did not take in account the radial heat losses, the values reported here are considered to be more accurate.…”

Section: Simplified Theoretical Analysissupporting

confidence: 90%

Forced forward smoldering experiments in microgravity

Bar-Ilan

Rein

Fernandez‐Pello

et al. 2004

Experimental Thermal and Fluid Science

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Results from two forward forced-flow smolder tests on polyurethane foam using air as oxidizer conducted aboard the NASA Space Shuttle (STS-105 and STS-108 missions) are presented in this work. The two tests provide the only presently available forward smolder data in microgravity. A complimentary series of ground-based tests were also conducted to determine, by comparison with the microgravity data, the effect of gravity on the forward smolder propagation. The objective of the study is to provide a better understanding of the controlling mechanisms of smolder for the purpose of control and prevention, both in normaland microgravity. The data consists of temperature histories from thermocouples placed at various axial locations along the fuel sample centerline, and of permeability histories obtained from ultrasonic transducer pairs also located at various axial positions in the fuel sample. A comparison of t he tests conducted in normal-and microgravity indicates that smolder propagation velocities are higher in microgravity than in normal gravity, and that there is a greater tendency for a transition to flame in microgravity than in normal gravity. This is due primarily to the reduced heat losses in the microgravity environment, leading to increased char oxidation. This observation is confirmed through a simplified one-dimensional model of the forward smolder propagation. This finding has important implications from the point of view of fire safety in a space-based environment, since smolder can often occur in the forward mode and potentially lead to a smolder-initiated fire.

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Section: Simplified Theoretical Analysissupporting

confidence: 90%

Forced forward smoldering experiments in microgravity

Bar-Ilan

Rein

Fernandez‐Pello

et al. 2004

Experimental Thermal and Fluid Science

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“…A schematic diagram of the experimental hardware is shown in Fig. 1 and described in detail in Walther et al (1999). The test duct, located in a 21.7 liters, semi-cylindrical, hermetically sealed aluminum combustion chamber (Fig.…”

Section: Experimental Hardware and Protocolmentioning

confidence: 99%

“…Two other thermocouples are placed radially at the center of the sample. The thermocouple locations are described in detail in Walther et al (1999). For the tests of the STS-105 mission, and the normal gravity experiments following it, in addition to the thermocouples, a novel ultrasonic imaging system (UIS) developed for the MSC project (Tse et al 1998) is applied to image the interior of the foam and determine the permeability of the material.…”

Section: Experimental Hardware and Protocolmentioning

confidence: 99%

“…These data have not been previously reported and provide new interesting information on the smolder process obtained with a newly implemented ultrasound probing system. The data from this test are used together with that from two other previously reported tests (Walther et al 1999) conducted at different airflow velocities to determine the dependence of smolder on the oxidizer-mass flux to the smolder front. Normal-gravity simulations of these tests together with complementary tests conducted varying elevated pressures are used to determine the effect of buoyancy on the smolder propagation.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Buoyancy on Opposed Smoldering

Bar-Ilan

Rein

Walther

et al. 2004

Combustion Science and Technology

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An experimental investigation on the effects of buoyancy on opposed flow smolder is presented. Tests were conducted on cylindrical samples of open-cell, unretarded polyurethane foams at a range of ambient pressures using the Microgravity Smoldering Combustion (MSC) experimental apparatus. The samples were tested in the opposed configuration, in which the flow of oxidizer is induced in the opposite direction as the propagation of the smolder front. These data were compared with opposed forced-flow tests conducted aboard STS-69, STS-77, and STS-105 and their ground based simulations. Thermal measurements were made of the smolder reaction to obtain peak reaction temperatures and smolder velocities as a function of the ambient pressure in the MSC chamber. The smolder reaction was also observed using high-frequency ultrasound pulses as part of the Ultrasound Imaging System (UIS). The UIS measurements were used as a second means of providing smolder propagation velocities as well as to obtain permeabilities of the reacting samples. Results of forced flow testing in normal gravity were compared to results in microgravity at a range of ambient pressures and forced flows. Results indicate that a critical oxidizer mass flux of roughly 0.5 to 0.8 g/m 2 s is required in normal gravity for a self-sustaining propagation in this configuration. In microgravity tests, self-sustained smolder propagation was observed at a significantly lower oxidizer mass flux of 0.30 g/m 2 s. Analysis suggests that the removal of buoyancyinduced heat losses in microgravity allows for self-sustained propagation at an oxidizer mass flux below the critical value observed in normal-gravity testing. Normal-gravity tests also show that the smolder propagation velocity is linearly dependent on the total oxidizer mass flux in an oxidizer-limited regime. Pressure effects on the chemical kinetics of a smolder reaction are inferred by comparison of normalgravity and microgravity tests and believed to be only weakly dependent on pressure (~P 1/3 ).

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“…Since the smoldering reaction is very weak and the flow velocity inside the solid fuel is relatively low, the buoyancy-induced flow can strongly influence the processes of smoldering combustion initiation, propagation and transition to flaming. Conducted on board NASA's space shuttles, previous microgravity smoldering combustion experiments [66][67][68] were focused on the smolder configurations of pure opposed flow (i.e. the reaction front propagates opposing the oxidizer flow) or forward flow (i.e.…”

Section: Microgravity Combustion Experimentsmentioning

confidence: 99%

Space experimental studies of microgravity fluid science in China

Long

Kang

et al. 2009

Chin. Sci. Bull.

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Microgravity fluid physics is an important part of microgravity sciences, which consists of simple fluids of many new systems, gas-liquid two-phase flow and heat transfer, and complex fluid mechanics. In addition to the importance of itself in sciences and applications, microgravity fluid physics closely relates to microgravity combustion, space biotechnology and space materials science, and promotes the developments of interdisciplinary fields. Many space microgravity experiments have been performed on board the recoverable satellites and space ships of China and pushed the rapid development of microgravity sciences in China. In the present paper, space experimental studies and the main results of the microgravity fluid science in China in the last 10 years or so are introduced briefly. microgravity fluid physics, microgravity gas-liquid two-phase flow, microgravity complex fluid, microgravity combustion, space biotechnologyThe technologies of rockets and satellites require the study of the fluid management problem in the storage tanks, and such problems of microgravity engineering in the microgravity environment have been studied in China during the development of space technology [1] . Studies on microgravity sciences in China were started in the late 1980s, when the scientists completed some space experiments on board the Chinese recoverable satellites by the promotion of the National HighTechnology Research Program of China. Main research subjects were the scientific experiments of materials science, in charged by the experts of the Institute of Semiconductor of the Chinese Academy of Sciences (CAS) and the Lanzhou Institute of Physics [2][3][4] , and experiments of space biology, in charged by the experts of life sciences in the CAS [5][6][7] . Some nice results were obtained, although resources of space experiments on board the recoverable satellite were relatively limited in the preliminary period.Microgravity fluid physics is an import part of microgravity sciences, and requires relatively complicated experimental facility in general, mostly the optical diagnostic instrumentations. Theoretical and experimental studies of the microgravity fluid physics on the ground were started relatively early in China [8] ; the scientists of China and Japan jointly completed the microgravity experiments of the thermocapillary convection in floating half zone [9] and drop Marangoni migration [10] using the JAMIC drop shift in Hokkaido and the MGLAB drop shift in Toki respectively before the foundation of the Beijing Drop Tower, and the experimental results were nice. China's first space experiment of fluid physics was completed 10 years later after the initiation of one of the materials science. The experiments of Marangoni convection and thermocapillary convection in two immiscible liquid layers were performed on board the SJ-5

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Space shuttle based microgravity smoldering combustion experiments

Cited by 41 publications

References 27 publications

Forced forward smoldering experiments in microgravity

Forced forward smoldering experiments in microgravity

The Effect of Buoyancy on Opposed Smoldering

Space experimental studies of microgravity fluid science in China

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