Measurements of turbulent boundary layer growth over a longitudinally curved surface

CER73-74RNM26.Prepared under Office of Naval Research - NR 062-414/6-6-68 (Code 438).I. C. Aero Tech. Note 74 - Jan. 1974.Includes bibliographical references (pages 23-25).January 1974.The result of an "additional rate of strain" on a turbulent parcel of fluid as it undergoes even mild streamline curvature can be very large. Yet until recently skin friction and heat transfer calculations have ignored this effect. Recent measurements over turbine cascades suggest curvature influences heat transfer by an order of magnitude. In addition there exists a strong analogy between the effects of centrifugal body forces and the buoyancy body force arising in density stratified flow in a gravity field. This note reports the results of a set of measurements of boundary layer development over convex and concave surfaces and compares the results with various turbulence models utilized in computational programs. A moderate curvature wind tunnel test section was constructed (δ/R = .01 to .02) to examine the influence of curvature on boundary layer structure. The boundary layer rate of growth, compared to that of a boundary layer in the same pressure gradient on a flat surface, was decreased on the convex surface and increased on the concave surface by ten to twelve percent as a result of only an apparent one to two percent perturbation on the size of the source terms in the Reynolds stress equations. Measurements are available of longitudinal static wall pressure, vertical stagnation pressure and single and cross-wire anemometer voltages at a sequence of five downstream stations. Lateral traverses at six heights for two downstream stations were completed over the concave side. Analog and digital interpretation of anemometer signals provided data of u, v, u'2, v'2, u'v', u'v'2 u'2v', u'3, and v'3.Contract N00014-68-A-0493-0001 Task NR 062-414

Review and classification of complex terrain models for use with integrated pest management program spray models

CEM89-90-RNM-l.Prepared for Forest Service Technology and Development Program, United States Department of Agriculture, Forest Service, Missoula, Montana.Includes bibliographical references (pages 19-22).April 1990

Comments on "Boundary-layer turbulence measurements with mass addition and combustion"

CER67-68RNM27.1967.Includes bibliographical references (page 3)

Final report: numerical and physical models of urban heat islands

CER74-75RNM26.Prepared by Robert N. Meroney, Principal Investigator.NSF Grant, ENG-72-03938 (GK33800).Includes bibliographical references (pages 17-20).December 1974.The response in the atmosphere of stratified shear layers to nonhomogeneous surface features is the subject of this report. Many interesting atmospheric circulations such as the sea breeze, the urban heat island, and flow over a heated island in the ocean (heat mountain) are induced by unbalanced bouyancy forces as a result of differential surface temperature. Such phenomena are very complex since the motion is coupled with several dominant features such as thermal stratification, high roughness elements, nonuniformity of surface roughness and/or surface temperature, nonplanar boundaries, and unsteadiness of boundary conditions. These problems may be successfully examined, however, by a coordinated laboratory-analytical research effort. This report summarizes a numerical and experimental research program which examined such a complicated airflow over nonhomogeneous surface complexities in two- and three-dimensional space

Wind tunnel study of stack gas dispersal at the Avon Lake Power Plant

CER73-74RNM-JEC-BTY-SKN35.April, 1974.Includes bibliographical references.Prepared under contract to Commonwealth Associates, Inc., Jackson, Michigan

Report on activities during tenure of air pollution fellowship from the Environmental Protection Agency under the Clean Air Act (P.L. 88-206)

CER73-74RNM15.October 1973

Wind-tunnel study of roofblok ballast block for high winds

Early draft.CER86-87BB-RNM-14.CSU Project 2-96960.January 1987.Includes bibliographical references (page 12)

Accelerated dilution of liquefied natural gas plumes with fences and vortex generators: final report, August 1981-May 1982

May 1982.Includes bibliographical references.Report No. GRI-81/0074.CER81-82KMK-RNM79.A wind-tunnel test program was conducted on a 1:250 scale model to determine the effects of fences and vortex generators on the dispersion of LNG plumes. The tests were conducted simulating continuous LNG boil-off rates of 20, 30 and 40 m3/min; 4, 7, 9 and 12 m/sec wind speed for fence data and 4, 7 and 9 m/sec wind speed for vortex generator data; six configurations; and two heights of fences and vortex generators. Plots of ground-level mean concentration contours were constructed. The highest concentrations were observed for the case of no fences and vortex generators. Fences and vortex generators created higher turbulence intensity in the wake and resulted into enhanced mixing thus reducing the ground-level hazards of LNG plumes. In general, the lower wind speed gave the higher ground-level concentration when fence or vortex generator interacted with the LNG plume. However, for the case of no fence or vortex generator the higher concentration persisted for longer downwind distances for 7 m/sec wind speed. As expected, the ground-level concentrations were increased with an increase in LNG boil-off rate but decreased with the increase in the fence/vortex generator height. In general, the solid fences gave the lower ground-level concentration as compared with the vortex generator with identical conditions. The double fences or vortex generators gave the maximum LNG plume dilution. However, the single fence or vortex generator near the source gave approximately the same dilution and hence, it would not justify the additional expenses of having second fence or vortex generator. It was also observed that the maximum LNG plume dilution occurs when the fence or vortex generator is closest possible to the LNG spill area.For Gas Research Institute, Contract No. 5014-352-0203

Turbulent diffusion in a stably stratified shear layer

Task IIB Research Technical Report Deseret Test Center.TR ECOM-0423-5; Reports control symbol OSD-1366.September 1969.Includes bibliographical references (pages 101-107).Diffusion of a passive substance released from a continuous point source in a stably stratified shear layer is investigated both theoretically and experimentally. Using Monin-Obukhov's velocity profile and assuming a vertical eddy diffusivity which is a power function of the stability parameter z/L, the Eulerian turbulent diffusion equation is solved to obtain expressions for vertical and longitudinal velocities of the center of mass of a cloud in the constant stress region. These expressions give physical substance to those suggested by Gifford (1962} and Cermak (1963} as intuitive extensions of Batchelor's Lagrangian similarity theory. The experimental investigation was made in the Army Micrometeorological Wind Tunnel at the Fluid Dynamics and Diffusion Laboratory of Colorado State University. The wind tunnel has a 6' x 6' x 80' test section. A stably stratified shear layer was produced by heating the air and cooling the wind tunnel floor. Detailed observations of the diffusion field, downwind ground and elevated point sources, have been made using Krypton-85 as a tracer. The concentration characteristics obtained from diffusion experiments show excellent agreement with those observed in the atmosphere. The data compares well with the predictions of similarity theory. It appears that the parameters evaluated in the field by Klug (1968) hold also for the wind tunnel data. The data support the assumption of a Gaussian effect of source height, for elevated releases, on the ground level concentration. An examination of the available solutions to the three dimensional diffusion equation as compared to the data suggests that the detailed diffusion patterns obtained from the wind tunnel experiments may be preferable over such solutions which require arbitrary specification of a lateral diffusivity.For U.S. Army Electronics Command, Atmospheric Sciences Laboratory, Contract No. DAAB07-68-C-0423