Driver gas flow with fluctuations

Johnson, J. A.; Jones, W R; Santiago, J.

doi:10.1088/0022-3727/13/8/011

Cited by 7 publications

(5 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We have previously confirmed that light attenuation is a direct measure oflocal N0 2 density by determining the extinction coefficient in a static environment with a range of pressures, which includes our operating conditions. 9 The value of the extinction coefficient obtained was quite consistent with the standard results. 4 We have confirmed that the observed fluorescence is a direct measure oflocal N0 2 density and a reliable indicator of N0 2 density fluctuations.…”

supporting

confidence: 87%

“…Indeed, the shock tube's contact surface has already provided some evidence of a coupling of turbulent effects with a nonequilibrium reaction. 9 Evidence of fully developed turbulence is found, in the sense that the fluctuation spectra show a power-law decay (i.e., Po:.wn) and the correlation profiles r ( 7) show appropriate time and length scales. Here we report on the most prominent features of the turbulent density fluctuations in a contact surface and the possibility of a direct relationship between the strength of turbulence and the rate of propagation of an exothermic molecular process.…”

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Turbulence in a reacting contact surface

Johnson

1990

Physics of Fluids A: Fluid Dynamics

View full text Add to dashboard Cite

Radiation damageinduced changes in silicon nitride membrane mechanical properties J. Vac. Sci. Technol. B 13, 3075 (1995); 10.1116/1.588325 Distortion analysis of stencil masks with stressrelief structures Turbulent features in a shock tube's contact surface with 2N0 2 ( = ) N2 0 4 are explored. Turbulent densities and velocities show an overall power-law dependence in the fluctuation spectra. At fixed reactant percentages, turbulence increases with increasing Reynolds number. At fixed Reynolds numbers, increasing the reactant percentages causes a reduction in turbulence and an increase in the relative strength of discrete high-frequency components in the density fluctuation spectra. The reliability of conventional chemical modeling for this system apparently decreases with increasing turbulence in a manner suggestive of reaction rate distortion, consistent with theoretical speculation.

show abstract

supporting

confidence: 87%

Section: Introductionmentioning

confidence: 97%

Turbulence in a reacting contact surface

Johnson

1990

Physics of Fluids A: Fluid Dynamics

View full text Add to dashboard Cite

show abstract

“…18 A TSI three-dimensional laser doppler velocimeter (LDV) system is used to confirm the existence of turbulence in all three components of the local velocity at the contact surface; it consists of a 6-W Ar-ion laser, a color separator, a color link (photo multiplier tubes and amplifiers), a burst correlator (signal processor) and a 486 computer controller. For seeding the flow, 0.8-/xm latex particles and incense smoke were used on both driver and driven sections.…”

Section: Experimental Facilities and Test Conditionsmentioning

confidence: 99%

Turbulent manipulation of condensation at a shock tube's contact surface

1995

View full text Add to dashboard Cite

IntroductionA N improved understanding of condensation phenomena in gaseous flow would have tremendous application to technological and scientific problems including droplet induced erosion in turbine blades, production of undesirable environmental conditions due to the condensation trails left by jet engines, and the inhibition of combustion in combustors. The usefulness of the shock tube for condensation studies was established by Wegener and Lundquist 1 followed by Glass and Patterson, 2 Barschdorff, 3 Sislian and Glass, 4 Kotake and Glass, 5 and Glass et al. 6 The development of the theory of nucleation rate and growth rate of the clusters is elaborated in the work of Lothe and Pound, 7 ' 8 Dunning, 9 Wegener,[10][11][12][13][14][15] In recent experiments carried out by Britan et al., 16 the effects of condensation on the parameters of the flow behind shock waves in water vapor were investigated in detail. Another recent experiment conducted by Schnerr and Bohning 17 investigated the effects of the heat addition by homogenous condensation on the compressible turbulent boundary layer. Nonetheless, in spite of all of this work, the relationship between the governing thermodynamic parameters and the simplest parameters in nucleation (such as onset and droplet growth rate) is not well understood at all.It is particularly clear that no experimental treatment has determined either the role which turbulence plays in the observations, if any, or the implications for such a possible role in the development of a reliable physical model. Implicitly, all current theories for droplet sizes also assume no role for turbulence. We, therefore, examine in this paper the possibility of a relationship between condensation and turbulence using the reliable and predictable turbulent environment of a shock tube's contact surface as a test system for water vapor condensation. We do not concern ourselves, at this juncture, with the onset of condensation. Our main interest is to investigate experimentally the effect that turbulence has on an existing condensation front which is moving with the turbulent gaseous media.A pressure driven shock tube ( Fig. 1) consisting of a driver section of 60 x 5.2 in., a driven section with a test section of 60 x 5.2 in., and an extension tube of 76 x 5.2 in. was used to carry out the experiment. Aluminized Mylar® sheets of various thicknesses were used as the material for the diaphragm which separates the driver section from the driven section. The compressed air is supplied to the driver section from a reservoir where the relative humidity of the air could be controlled by controlling the temperature in the driver gas. A heating tape is wrapped around (outside) the entire driver section, and a thermocouple probe is used in the driver section to measure the initial temperature.The test section has three stations for optical diagnostics, two of which consist of four perpendicular glass ports; the other station has two inline glass ports. The test section is also equipped with several ports for pressur...

show abstract

“…The observed grain size of the fibre in the perpendicular direction is ca. 5 nm (W hittaker et al 19906) and this is relatively insensitive to h eat tre a tm e n t (Johnson et al 1980). The actual value for Af± will depend on the value selected for a which, in view of the disordered arrangem ent of layer planes norm al to th e fibre axis, clearly should be greater th an 2.…”

Section: Comparison With Experimental Datamentioning

confidence: 99%

Thermal transport properties of carbon-carbon fibre composites III. Mathematical modelling

Whittaker

Taylor

1990

Proc. R. Soc. Lond. A

View full text Add to dashboard Cite

Measured thermal transport data are interpreted using data obtained by careful microstructural characterization concerning the porosity distribution and graphite grain sizes. The separate thermal conductivity components for one-dimensional composites are deduced using a simple series addition to determine ג f1 and ג m1 and using an adaptation of the Bruggeman analysis for calculating ג f┴ and ג m┴ . Parallel to the fibre axis the calculated thermal conductivities are shown to be in good agreement with existing theories of the thermal conductivity of graphite using experimentally determined values of grain size. The derived data are recombined in a simple series model to predict the thermal conductivity of two-dimensional composites containing a different fibre volume fraction and porosity level. Good agreement with measured data is obtained.

show abstract

Driver gas flow with fluctuations

Cited by 7 publications

References 13 publications

Turbulence in a reacting contact surface

Turbulence in a reacting contact surface

Turbulent manipulation of condensation at a shock tube's contact surface

Thermal transport properties of carbon-carbon fibre composites III. Mathematical modelling

Contact Info

Product

Resources

About