Laboratory Investigation And Numerical Simulation Of Thermally Stratified Shear Flow

The dynamic characteristics of thermally stratified shear flow in straight and curved flumes with 3 bending angles of 45° , 90° and 180° have been experimentally studied respectively. The mathematical models applying in straight and curved flumes were established. The turbulent characteristics at the interface of stratified shear flow have been analyzed ulteriorly by numerical experimental investigation. The main conclusions include as follows:1. The advances in the research of the characteristics of stratified flow are reviewed overall. The necessary and feasibility of the application of precise instruments and mathematical models in the research of stratified flow in straight and curved flume are pointed out.2. The straight laboratory flume of thermally stratified shear flow has been established. Several experimental test runs with different discharge ratio of warm water to cold water were conducted. With precise instruments such as MicroADV and digital thermometer, the time-averaged and turbulent characteristics of stratified shear flow in the straight flume are researched, and the mechanism of turbulent mixing between warm and cold water layers is discovered. The analysis of stability for stratified shear flow in the straight flume is conducted.3. Three curved flumes with bending angles of 45°, 90° and 180° of thermally stratified shear flow have been established respectively. Several experimental test runs with different discharge ratio of warm water to cold water were conducted. With precise instruments such as MicroADV and digital thermometer, the time-averaged and turbulent characteristics of stratified shear flow in the curved flumes are researched. The bend effect on mixing and stability for stratified shear flow is explored.4. A rectangular grid finite volume algorithm for lateral 2-Dimension anisotropic k-ε model with buoyancy-correction is established. By the calculation for some laboratory stratified shear flow cases in straight flume, it is shown that the buoyancy-correction of the k-ε model is the establishment of experimental relationship between the model and special stratified flow pattern. The anisotropic k-ε model only adapts to simulate the strong stratification, so it's applicability is poor.5. A rectangular grid finite volume algorithm for 3-dimension second-moment Reynolds stress model is established, and used to simulate the laboratory stratified shear flow cases in straight flume successfully. By numerical experimental investigation, the turbulent characteristics at the interface of thermally stratified shear flow in straight flume are discussed ulteriorly.6. An unstructured grid finite volume algorithm for 3-dimension second-moment Reynolds stress model is established, and used to simulate the laboratory stratified shear flow cases in strong curved flume with bending angle of 180° successfully. By numerical experimental investigation, the turbulent characteristics at the interface of thermally stratified shear flow in strong curved flume with a bending angle of 180° are discussed ulteriorly.