Moveable Wall Research Articles

Adsorption and wetting on moveable walls

Polystyrene latex spheres, colloidally suspended at very low volume fraction in critical and nearcritical mixtures of 2,6-lutidine and water (LW), have been observed to segregate strongly into a complete wetting phase when the LW mixture is placed in its two-phase region near T c. The wetting temperature, T w, is observable as that at which colloidal particles abruptly begin to migrate to the meniscus. In the one-phase region near the coexistence temperature, the particles aggregate reversibly through a process which appears to be interpretable as a form of capillary condensation.

Self‐Sustained Pressure Oscillations in Two‐Dimensional Cavity

The pressure oscillations within a two-dimensional, rectangular cavity have been explored. The flow was subsonic and the chord-to-depth ratio of the cavity ranged between 0.25 and 1.25. The experimental setup, comprised a plexiglass channel-cavity model, was inserted within the test section of a wind tunnel. The moveable walls of the cavity were adjusted for various cavity geometries. A pressure transducer was flush mounted along the upstream wall of the cavity and was used to monitor, with the help of an oscilloscope, the pressure fluctuations within the cavity. Within a Strouhal number range of 0.4 - 2.4, periodic pressure fluctuations as high as 50% of the free-stream dynamic pressure were observed. The modulation of the external flow is influenced by the cavity which acts as a simple harmonic oscillator with a certain natural frequency. As the velocity of the external flow is increased gradually, the frequency of the pressure fluctuations experiences step changes, shifting to higher or lower frequency levels. Of the two parameters describing the cavity geometry and their effects on pressure oscillations, the cavity length appears to influence the frequency, and the cavity depth effects the amplitude. The maximum amplitude of the pressure oscillations within the cavity were observed to occur under mode 2 and for a cavity geometry corresponding to a chord-to-depth ratio of about 0.5.

An Improved Technique for Interpersonal Projective Assessment

An improved technique for projective assessment of interpersonal relations was developed for use with children. The poor quality of available grids and human figures necessitated the development of a model grid and contemporary scale-sized human figures. A scale model of a “family” room was created utilizing a metal kitchen counter-top mat marked with thin plastic tape in 2.5-cm. squares. Heavy mat board was cut and joined at each corner to form moveable walls for the room. Human figures were cut from sewing pattern books, glued to mat board, and stabilized with a cork and magnetic tape base. It was proposed that the model and figures could be used for other projective situations such as play therapy and sociometric analysis.

Pitch and petroleum coke additions to coke oven charges

AbstractSeveral pitch materials and a petroleum coke were added to coke oven charges in an attempt to make good metallurgical coke from Canadian coal of poor coking quality. Coal and petroleum pitches were added to a low fluid western Canadian coal of medium volatile bituminous rank, and the blends coked in a technical‐scale moveable wall test oven having a 230‐kg charge capacity. Pitches improved coke tumble test indices, the principal coke quality parameter related to blast furnace performance. Varying levels of petroleum coke were added to an eastern Canadian coal of high volatile bituminous rank, and the blends, some partially briquetted, were carbonized in a test oven. Tumble indices of coke from the partially briquetted charges approached an acceptable level. These investigations confirm that petroleum products as well as coal derivative can play a useful part in the production of a metallurgical strength coke from poor or non‐coking coals.

The transmission loss of a wall incorporating an array of resonators

Resonators, and in particular Helmholtz resonators, are often used to enhance the reflection loss of a given surface. In this paper, the associated effect on transmission loss is analyzed. The mathematical model consists of a rigid moveable wall of infinite extent and molded to form slotted cavities which create an array of line resonators. The pressure within each cavity is governed by the wave equation and the wall motion is assumed to be proportional to the net pressure on the wall surfaces. In response to a normally incident plane wave, the transmitted pressure is determined and numerical results are presented for various configurations. It is shown that the resonator array can significantly enhance the transmission loss of the wall. The effects of slot width, wall mass and the cascading of cavities of differing dimensions are discussed.

Rayleigh scattering: Orientational motion in highly anisotropic liquids

Light scattering studies of the depolarized Rayleigh line are reported for liquid benzene over the temperature range +13 to 76°C and for other substituted benzenes. Values of the 〈 P2(o)P2(t)〉 and 〈 Ṗ2(o)Ṗ2(t)〉 correlation functions calculated from these spectra show considerable free rotor behavior (∼ 15° steps) and incomplete loss of memory after collision. Further consideration of the 〈 Ṗ2(o)Ṗ2(t)〉 correlation allows calculation of the angular velocity correlation function. The time between collisions, τBC, is also obtained and found to be in good agreement with a ``moveable wall'' cell model. It is proposed that the ``shoulder'' noted in the wings of many anisotropic liquids is caused by incomplete loss of memory after collision.