Values Of Local Coefficients Research Articles

ТЕПЛООБМЕН И ТРЕНИЕ В КАНАЛАХ СУДОВЫХ ГАЗОТУРБИННЫХ ЭНЕРГЕТИЧЕСКИХ УСТАНОВОК ПРИ ИЗМЕНЕНИИ ДИНАМИКИ УВЕЛИЧЕНИЯ ТЕМПЕРАТУРЫ РАБОЧЕГО ТЕЛА

He article presents the results of the experimental research of non-stationary effects and the influence of transiency caused by burst heating of the gas flow on values of local coefficients of friction and heat emission on the initial section of the cylindrical channel. The main reason of destruction of the main engine is local heating of some elements, i.e. the process of heat-transfer that occurs outside the combustion chamber in fire tubes, where at the entrance of turbine generates heated gas flow in non-isothermal environment. This heated gas flow rotates the turbine. Kinematic and heat structures of this gas flow at the studied period of time undergo the mutual effect of destabilizing factors, such as non-isothermal effect of the longitudinal pressure gradient caused by the uprising of the dynamic and heat transiency. Friction coefficient Cf and coefficient of heat losses St are the most important criteria of the gas flow, which characterize gas dynamics and heat exchange of the gas flow. Non-stationarity has an essential effect on the values of friction coefficient and heat loss coefficient, which increase or decrease in 2.0-2.5 times, compared to their quasisteady analogues. Beyond non-stationary process, when the temperature of working body becomes stationary, the key role is played by the thermal head which causes laminarization phenomenon of the of the heat turbulent boundary layer.

Gas–liquid and liquid–solid mass transfers in two types of stationary catalytic basket laboratory reactor

Measurements of gas–liquid and liquid–solid mass transfer coefficients were performed in two types of three-phase laboratory reactor equipped with stationary catalytic basket and multiple impeller. Those reactors are called Robinson–Mahoney reactors. Local liquid–solid mass transfer coefficients were measured using naphtol particle dissolution in n-heptane at several agitation speeds. Experiments had shown that local coefficients depended on the particle locations in the basket and agitation speeds. The local coefficient values and profiles were quite similar for both studied reactors even though the reactor designs were different. Similar values of RM basket thicknesses might account for this phenomenon because the liquid–solid mass transfers could be correlated with the ones in packed beds with forced liquid circulation. Gas–liquid mass transfer coefficients were measured using standard dynamic absorption methods in air–water or hydrogen–gas oil system. As in stirred tanks, the gas–liquid mass transfers were linked to the impeller designs and characteristics (gas-inducing or classical impeller) and to the operating conditions such as agitation speeds and fluid properties. However, correlations applicable to stirred tank reactors can be used with Robinson–Mahoney reactors, the baskets behaving like additional baffles or reduction of tank diameters.

Perception of coarticulated speech with contrastively enhanced spectrotemporal patterns

High-level contrastive mechanisms cause perception of auditory events to be influenced by spectral and temporal properties of surrounding acoustic context, and may play a role in perceptual compensation for coarticulation in human speech. However, it is unknown whether auditory contrast is incorporated optimally to compensate for different speakers, languages and situations or whether amplification of the processes involved would provide additional benefit, for example, in the perception of hypoarticulated speech, under adverse listening conditions, or in an incompletely acquired language. This study examines effects of artificial contrastive modification of spectrotemporal trajectories on the intelligibility of connected speech in noise by native and non-native listeners. Adopting methods known to improve automatic classification of speech sounds, we model contrast-providing context as an averaged estimated vocal tract function (LPC-derived log area ratio coefficient vector) over a Gaussian-weighted temporal window. Local coefficient values are adjusted from this context based on previously observed contrastive perceptual tendencies, and the intelligibility of the resulting speech is compared with that of unmodified trajectories across listener language backgrounds. Results are discussed with respect to implementation and applicability of general auditory processes.

Thwaites' Method In Laminar Boundary Layer

Thwaites' method can be applied to find the boundary layer characteristics for either similar or nonsimilar flow for a variety of boundaries ranging from a simple flat plate (Blasius's Solution(1)) to a symmetrical airfoil. The flow properties to be determined include potential flow velocity distribution, displacement thickness, momentum thickness and coefficient of friction. Furthermore,the location of flow separation is readily obtainable from the numeric value of local coefficient of friction. Thwaites' Method is able to provide satisfactory approximate solution to different types of simple boundary as long as the flow is laminar and not separated. For a complex curvature such a an airfoil Thwaite' Method is yet to be tested. In this context, we will look into the applicability of Thwaites' Method for a particular symmetrical airfoil, NACA 0012.