The study of base heating by radiation from exhaust gases final report, oct. 1, 1963 - sep. 30, 1964

Base heating by radiation from exhaust gase

Comparison of flow and dispersion properties of free and wall turbulent jets for source dynamics characterisation

The objective of this paper is to provide an investigation, using large eddy simulations, into the dispersion of aircraft jets in co-flowing take-off conditions. Before carrying out such study, simple turbulent plane free and wall jet simulations are carried out to validate the computational models and to assess the impact of the presence of the solid boundary on the flow and dispersion properties. The current study represents a step towards a better understanding of the source dynamics behind an airplane jet engine during the take-off and landing phases. The information provided from these simulations can be used for future improvements of existing dispersion models

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

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

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

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

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

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

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

A non-hybrid method for the PDF equations of turbulent flows on unstructured grids

In probability density function (PDF) methods of turbulent flows, the joint PDF of several flow variables is computed by numerically integrating a system of stochastic differential equations for Lagrangian particles. A set of parallel algorithms is proposed to provide an efficient solution of the PDF transport equation, modeling the joint PDF of turbulent velocity, frequency and concentration of a passive scalar in geometrically complex configurations. An unstructured Eulerian grid is employed to extract Eulerian statistics, to solve for quantities represented at fixed locations of the domain (e.g. the mean pressure) and to track particles. All three aspects regarding the grid make use of the finite element method (FEM) employing the simplest linear FEM shape functions. To model the small-scale mixing of the transported scalar, the interaction by exchange with the conditional mean model is adopted. An adaptive algorithm that computes the velocity-conditioned scalar mean is proposed that homogenizes the statistical error over the sample space with no assumption on the shape of the underlying velocity PDF. Compared to other hybrid particle-in-cell approaches for the PDF equations, the current methodology is consistent without the need for consistency conditions. The algorithm is tested by computing the dispersion of passive scalars released from concentrated sources in two different turbulent flows: the fully developed turbulent channel flow and a street canyon (or cavity) flow. Algorithmic details on estimating conditional and unconditional statistics, particle tracking and particle-number control are presented in detail. Relevant aspects of performance and parallelism on cache-based shared memory machines are discussed.Comment: Accepted in Journal of Computational Physics, Feb. 20, 200