Turbulence measurements in polymer solutions using hot-film anemometry

Hot-film anemometry was used to study the detailed structure of turbulence (intensities, energy spectra, and auto-correlations) in Newtonian solvents, non-drag reducing polymer solutions, and drag reducing polymer solutions. This was done in two smooth wall tubes with diameters of 1.0 inch and 2.0 inches. A probe traversing mechanism was used for measurements at radial positions from the center to as near the wall as possible for both the film probes (r/a=0.85 in the 2-inch tube) and the impact tubes (r/ a=0.98). The impact tubes were used to measure velocities for film probe calibration. The solvents used in this investigation were toluene, cyclohexane, and benzene. Three concentrations of a medium molecular weight polyisobutylene (Vistanex L-80, molecular weight about 720,000) in cyclohexane, two concentrations of the same polymer in benzene, two concentrations of a high molecular weight polymethyl methacrylate (Plexiglas, molecular weight about 1,500,000) in toluene, one concentration of a low molecular weight polymethyl methacrylate (V-100 molding powder, molecular weight about 110,000) in toluene, three concentrations of a high molecular weight polyisobutylene (Vistanex 1-200, molecular weight about 4,700,000) in toluene, and one concentration of the same polymer in cyclohexane were used. In the liquids not showing drag reduction a viscous and/ or elastic effect was found for both turbulence intensities and energy spectra. Turbulence intensities were higher and energy spectrum frequencies were lower for the polymer solutions of high viscosity. Unfortunately the most viscous solutions were also elastic. So purely viscous liquid studies will be necessary to distinguish between elastic and viscous effects. During drag reduction it was found that the energy spectra changed little from purely viscous solvents. The turbulence intensities, however, showed very unusual effects. The intensities relative to friction velocity increased at low drag ratio values (high drag reduction), rather than remain constant as expected from mixing length considerations. This behavior was dependent upon the degree of mechanical polymer degradation, lower intensities occurring for fresh than for degraded solutions during drag reduction. Normal stress differences (P₁₁ - P₂₂) were measured for two of the solutions used in this investigation, one showing drag reduction at attainable flow rates in the l-inch tube, the other showing drag reduction only in 0.5-inch and smaller tubes. Both solutions yielded normal stress differences of about the same level. A quantitative viscoelastic mechanism of drag reduction was tested using the viscosity and normal stress data for the two solutions discussed above. The drag reduction mechanism demonstrated the relative effects of elasticity and viscosity on drag reduction. The adequate prediction of drag ratios for two solutions at two flow rates in each of two tube sizes demonstrated the validity of the mechanism and the reasonableness of the assumptions made --Abstract

Comparison Of Lagrangian Time Correlations Obtained From Dispersion Experiments And From Space‐time Correlation Functions

No Abstracts. Copyright © 1969 American Institute of Chemical Engineer

Hot‐film Anemometry Measurements Of Turbulence In Pipe Flow: Organic Solvents

Longitudinal turbulence intensities, autocorrelations, and energy spectra have been measured in the flow of toluene, benzene, and cyclohexane in smooth, round 1‐ and 2‐in. I.D. tubes. These measurements were made with a constant‐temperature hot‐film anemometer and covered radial positions from the center to r/a = 0.85 in the 2‐in. tube and to r/a = 0.75 in the 1‐in. tube. The turbulence intensity data were found to be similar to those obtained for air in a 10‐in. pipe by Laufer. A slight diameter effect was observed, the intensities in the 1‐in. tube being slightly lower than those in the 2‐in. tube at equal Reynolds numbers. The energy spectra were similar to the spectrum reported by Lee and Brodkey for water. The spectra reached higher frequencies at the lowest measurable energy levels for higher velocities. There was little effect of tube diameter or radial position on the spectra from the center to r/a = 0.85. A short inertial subrange with a log‐log slope of −5/3 seemed evident in high velocity spectra, and the log‐log slope of −7 was approached at high frequencies by the lowest velocity spectrum. The peak energy dissipation frequencies for all the energy spectra measured were approximately proportional to bulk mean velocity to the 1.4 power with little effect of tube diameter or radial position from the center to r/a = 0.85. Integral scales of the turbulence were proportional to bulk mean velocity to a power less than one for a given tube. These measurements indicated that the ratio of integral scale to pipe diameter is not a function of Reynolds number only. Microscale values were relatively independent of velocity and pipe diameter. Copyright © 1967 American Institute of Chemical Engineer

Development of global model for atmospheric backscatter at CO2 wavelengths

The improvement of an understanding of the variation of the aerosol backscattering at 10.6 micron within the free troposphere and the development model to describe this was undertaken. The analysis combines theoretical modeling with the results contained within three independent data sets. The data sets are obtained by the SAGE I/SAM II satellite experiments, the GAMETAG flight series and by direct backscatter measurements. The theoretical work includes use of a bimodal, two component aerosol model, and the study of the microphysical and associated optical changes occurring within an aerosol plume. A consistent picture is obtained, which describes the variation of the aerosol backscattering function in the free troposphere with altitude, latitude, and season. Most data are available and greatest consistency is found inside the Northern Hemisphere

Development of a global model for atmospheric backscatter at CO2 wavelengths

The variation of the aerosol backscattering at 10.6 micrometers within the free troposphere was investigated and a model to describe this variation was developed. The analysis combines theoretical modeling with the results contained within three independent data sets. The data sets used were obtained by the SAGE I/SAM II satellite experiments, the GAMETAG flight series, and by direct backscatter measurements. The theoretical work includes use of a bimodal, two component aerosol model, and the study of the microphysical and associated optical changes occurring within an aerosol plume. A consistent picture is obtained that describes the variation of the aerosol backscattering function in the free troposphere with altitude, latitude, and season

Drag Reduction In Solid‐fluid Systems

Pressure drop measurements were made on a variety of dilute solid‐liquid suspension systems in order to study the effects of particle shape and size, concentration, fluid viscosity, and tube diameter on friction factor. The central objective was to determine under what conditions drag reduction would occur. Copyright © 1975 American Institute of Chemical Engineer

Assessing the Value of Coordinated Sire Genetics in a Synchronized AI Program

Synchronized artificial insemination was used to inseminate cows using different types of sire genetics, including low-accuracy, calving-ease, and high-accuracy. These three calf sire groups were compared to calves born to cows bred using natural service. We found substantial production efficiency grains, carcass merit improvement, and economic value to calves born to cows following a synchronized artificial insemination program with high-accuracy semen included. The economic advantage to the high-accuracy calf sire group was computed to be in the neighborhood of $40 to$80/head, relative to the natural service calf sire group.artificial insemination, beef, cow, carcass, feed-out, genetics, pre-conditioning, sire synchronization., Agricultural Finance,

Primary Application of the Hydrocyclone for the Separation of Biological Solids from Dispersed Bacterial Systems

Bioenvironmental Engineerin