In the first part of our paper, we have extended the concepts of the classical convolution and the convolution scalar product given by I. Hlaváck and presented the concepts of the convolution vector and the convolution vector scalar product, which enable us to extend the initial value as well as the initial-boundary value problems for the equation with the operator coefficients to those for the system of equations with the operator coefficients.In the second part of this paper, based on the concepts of the convolution vector and the convolution vector scalar product, two fundamental types of reciprocal theorems of the non-local micropolar linear elastodynamics for inhomogeneous and anisotropic solids are derived.In the third part of this paper, based on the concepts and results in the first and second parts as well as the Lagrange multiplies method which is presented by W. Z. Chien, four main types of variational principles are given for the nonlocal micropolar linear elastodynamics for inhomogeneous and anisotropic solids. These are the counterparts of the variational principles of Hu-Washizu type, Hellinger-Reissner type and Gurtin type in classical elasticity as well as Hlaváck type and Iesan type in local micropolar and nonlocal elasticity. Finally, we have proved the equivalence of the last two main variational principles which are given in this paper. 相似文献
A two-color particle image velocimetry (PIV) technique has been applied to a single-cylinder motored research engine. Two-color PIV is a quantitative planar velocity measurement technique that can unambiguously determine the velocity magnitude and direction.
The work includes the development of an interrogation system, a series of computer simulations to determine the performance of the technique under various conditions, the comparison of these results to similar ones obtained for an autocorrelation PIV system, and a test of the technique by reconstructing the velocity field of a uniform jet flow.
The technique was then applied to the in-cylinder flow field of a motored single-cylinder, cup-in-head, research engine. A total of 27 instantaneous velocity fields were obtained at a single measurement plane for a single operating condition of the engine. The data were analyzed to yield ensemble-averaged velocity and velocity fluctuation. 相似文献
The results of an experimental investigation depicting the effects of swirl profile on confined flows in a sudden-expansion coaxial dump combustor are presented. Three swirlers (free vortex, forced vortex, and constant angle) with the same nominal swirl number were designed and fabricated to study the effects of swirl type on the isothermal dump combustor flow field. Imparting swirl to the inlet flow resulted in a considerable reduction of the corner recirculation length, a marked increase in turbulent mixing activity, and in one case creation of a central recirculation zone. This article highlights the importance of the combustor inlet swirl profile and shows that swirl type as well as swirl strength can affect the flow field significantly. The present database is well suited for numerical codes development and validation. 相似文献
A direct numerical simulation (DNS) of a recirculating, swirling flow is performed at a Reynolds number of 5000. Detailed
one and two point statistics are presented in this paper. Flow visualization and frequency analysis are used to identify a
precessing vortex core and to characterize its position, extent and influence on the flow field. The results are compared
with laser Doppler velocimetry (LDV) measurements as well as large eddy simulation (LES) data reported in the literature.
The present work constitutes a first step in setting up a DNS data base for complex flows. 相似文献
A series of unconfined swirling premixed natural gas/air flames was investigated. Reynolds-numbers spanned from 10,000 to 42,300. Respective isothermal flows were studied additionally to gain insight into changes of fluid dynamical features caused by combustion. Statistical moments, Reynolds-stresses, temporal time scales, spatial length scales, and power spectral densities were deduced from one- and two-point laser Doppler velocimetry (LDV) data. Properties of the turbulent flows and dependencies on Reynolds-number, swirl number, and chemical reactions are discussed. Most distinct differences between combusting and isothermal flows were precessing vortex cores (PVC) occurring only for the latter cases. The study is aimed to serve as a database of a generic flame geometry featuring important characteristics of industrial applications for validation of numerical simulations. Therefore, nozzle exit profiles as important inlet conditions to numerical simulations are thoroughly documented. 相似文献