Nonlinear lift and pressure distribution of slender conical bodies with strakes at low speeds

Nonlinear lift and pressure distribution of slender conical bodies with strakes at low spee

Nonconical theory of flow past slender wing bodies with leading-edge separation

Nonconical theory of flow past slender wing bodies with leading edge separatio

Investigation of the stability, radiation, and structure of laminar coflow diffusion flames of CH4/NH3 mixtures

The stability, radiation, and structure of laminar axisymmetric CH4/NH3/air diffusion flames have been studied using photographic images, spectrally resolved measurements of flame radiation, and the spatial distribution of temperature and major species mole fractions obtained by spontaneous Raman scattering. The fit procedure for the Raman spectra of NH3 includes a hitherto unquantified overtone feature, whose inclusion in the fit significantly improves the NH3 fraction obtained. Nitrogen is used to replace NH3 to separate chemical effects of NH3 addition from those due to dilution. The results show that NH3 addition drastically reduces radiation from carbon-containing species, with progressively increasing strong chemiluminescence from excited NO2 and NH2, indicating a substantial change in flame chemistry. While the Rayleigh/Mie scattering from soot particles is still observed in the Raman spectra at 28% NH3 addition, 46% NH3 in the fuel is seen to suppresses soot formation effectively. The measured axial and radial profiles of temperature and major species indicate a substantial contribution from radial transport from the reaction zone, seriously complicating the relation between composition, mixture fraction, and the corresponding equilibrium temperature and mole fractions

Tracing/training rebellion - object work in Meyerhold's biomechanics

[First paragraph] Lying in the Russian State Archive of Literature and Arts in Moscow (RGALI) is a nine-page document entitled Programme of Biomechanics, Meyerhold Workshop (1922). Though modest in size, it is an unashamedly ambitious programme, which sought to redefine acting in a post-revolutionary context and to place performer training in Russia on a par with science. ‘The task of the biomechanical laboratory is to work out through experimentation a biomechanical system of acting and of actor’s training’ (Hoover 1974: 314), the document claims, setting out a dedicated model of Practice as Research, seventy years before the term became common place in the UK

(Non)Equilibrium of OH and Differential Transport in MILD Combustion:Measured and Computed OH Fractions in a Laminar Methane/Nitrogen Jet in Hot Coflow

Spatial distributions of temperature, major species, and OH mole fractions under moderate or intense low-oxygen-dilution (MILD) conditions in a laminar-jet-in-hot-coflow configuration were measured using spontaneous Raman and laser-induced-fluorescence methods. A preheated mixture of 18% CH4/82% N2 at 1100 K was used as fuel, while the products of a laminar, flat, premixed burner-stabilized flame with an equivalence ratio of 0.8 at 1550 K were used as the oxidizer. For comparison, experiments replacing the fuel by pure N2 were also performed. The measurements are compared with the results of numerical simulations performed using the GRI-Mech 3.0 chemical mechanism and a multicomponent mixture-averaged transport model. Analysis of the data shows that the maximum axial and radial temperature and OH mole fraction occur on the lean side of the stoichiometric mixture fraction. MILD combustion generates maximum OH mole fractions of ∼700 ppm in the radial profiles close to the burner exit and ∼300 ppm along the centerline, more than five times lower than those measured in equivalent methane/air diffusion flames. Overall, good qualitative and quantitative agreement is found between the results of detailed computations and experiments, with the maximum differences observed in the axial OH profiles, which are just outside the estimated experimental uncertainty. Analysis of the computational results shows that differential diffusion hinders the use of the mixture fraction to estimate the equilibrium temperature and species fractions, causing an overestimation of the stoichiometric temperature by ∼200 K. Calculating the equilibrium quantities based on the local (computed) species fractions shows an axial temperature profile that differs from that experimentally/computationally determined by less than 25 K. The analysis further shows that the measured OH mole fractions are roughly three times higher than the (locally determined) equilibrium value

Experimental and Modeling Investigation of the Effectof H2S Addition to Methane on the Ignition and Oxidation at High Pressures

The autoignition and oxidation behavior of CH₄/H₂S mixtures has been studied experimentally in a rapid compression machine (RCM) and a high-pressure flow reactor. The RCM measurements show that the addition of 1% H₂S to methane reduces the autoignition delay time by a factor of 2 at pressures ranging from 30 to 80 bar and temperatures from 930 to 1050 K. The flow reactor experiments performed at 50 bar show that, for stoichiometric conditions, a large fraction of H₂S is already consumed at 600 K, while temperatures above 750 K are needed to oxidize 10% methane. A detailed chemical kinetic model has been established, describing the oxidation of CH₄ and H₂S as well as the formation and consumption of organosulfuric species. Computations with the model show good agreement with the ignition measurements, provided that reactions of H₂S and SH with peroxides (HO₂ and CH₃OO) are constrained. A comparison of the flow reactor data to modeling predictions shows satisfactory agreement under stoichiometric conditions, while at very reducing conditions, the model underestimates the consumption of both H₂S and CH₄. Similar to the RCM experiments, the presence of H₂S is predicted to promote oxidation of methane. Analysis of the calculations indicates a significant interaction between the oxidation chemistry of H₂S and CH₄, but this chemistry is not well understood at present. More work is desirable on the reactions of H₂S and SH with peroxides (HO₂ and CH₃OO) and the formation and consumption of organosulfuric compounds

Nanostructure and thermal power of highly-textured and single-crystal-like Bi2Te3 thin films

Bi2Te3-based alloys are known to have outstanding thermoelectric properties. Although structure-property relations have been studied, still, detailed analysis of the atomic and nano-scale structure of Bi2Te3 thin film in relation to their thermoelectric properties remains poorly explored. Herein, highly-textured (HT) and single-crystal-like (SCL) Bi2Te3 films have been grown using pulsed laser deposition (PLD) on Si wafer covered with (native or thermal) SiOx and mica substrates. All films are highly textured with c-axis out-of-plane, but the in-plane orientation is random for the films grown on oxide and single-crystal-like for the ones grown on mica. The power factor of the film on thermal oxide is about four times higher (56.8 mu W.cm(-1).K-2) than that of the film on mica (12.8 mu W.cm(-1).K-2), which is comparable to the one of the polycrystalline ingot at room temperature (RT). Reduced electron scattering in the textured thin films results in high electrical conductivity, where the SCL film shows the highest conductivity. However, its Seebeck coefficient shows a low value. The measured properties are correlated with the atomic structure details unveiled by scanning transmission electron microscopy. For instance, the high concentration of stacking defects observed in the HT film is considered responsible for the increase of Seebeck coefficient compared to the SCL film. This study demonstrates the influence of nanoscale structural effects on thermoelectric properties, which sheds light on tailoring thermoelectric thin films towards high performance