CALCULATION OF FLOW CHARACTERISTICS IN HEAT TURBOMACHINERY TURBINE STAGE WITH DIFFERENT THREE DIMENSIONAL SHAPE OF THE STATOR BLADE WITH ANSYS CFX SOFTWARE
Main purpose of the presented work was the investigation of influence of three dimensional blades over flow characteristics. The paper presents comparison between experimental and CFD (Computational Fluid Dynamics) data so called verification test, impulse turbine stage with Frozen Rotor and Transient Rotor Interface modeling. Static pressure distribution was measured at mid span of the blade. The paper discusses secondary flow phenomena.
Validation of Numerical Computations and Turbulence Models Combinations for Gas Turbine Cascade Blade Flow
The accuracy of computer codes for turbo-machinery turbulent flow field calculations relies strongly on the type and behavior of the turbulence model used in the computations. Analysis of different Reynolds Average Navier-Stokes Equation (RANS) based turbulence models was applied to predict the flow field in the linear first stage gas turbine cascade blade. The experimental investigation is also introduced to validate the accuracy of turbulence models. This was done by using five linear cascade blades tested in an open jet type low-speed subsonic wind tunnel. The static pressure distribution was measured at the midspan of cascade middle blade by using static pressure taps. The numerical results obtained from different turbulence model simulations is individually reviewed for the correctness of its predictions and compared with the experimental data in terms of integrated flow parameters, such as static pressure coefficient distribution on both blade sides. The results show that RNG k-e turbulence model gave the best prediction of pressure distribution when compared with the experimental data. Prediction of standard k-e and k-ω turbulence models fail to predict accurately the flow field parameters in cascade passage. Prediction of (k-e) turbulence model overestimate the turbulence kinetic energy values, especially in the regions of high velocity at blade suction side, also not accurately predict the flow separation on the blade suction side.
Experimental study on bond behavior between high-strength grout and deformed steel bars
Abstract Engineers use high-strength grout to connect precast concrete members for its low shrinkage and good fluidity. This paper designed 87 central pull-out specimens using the control variable method to investigate the influence of factors on the rebar-grout bond property such as compressive strength, steel grade, bar diameter, transverse stirrups, and bond length. The test result showed that improving grout compressive strength (85.8 MPa–122.7 MPa) cannot improve the bond strength, which was different from the previous conclusions of concrete pull-out tests. Simplified formulas were presented for calculating the characteristic values of bond strength, residual strength, peak slip, and relative slip of load-holding platform based on parameter analysis. Then, a constitutive model was proposed to predict the full-range bond stress-slip curve of high-strength grout and steel bar specimens from bearing to failure. Finally, FEA models were established to evaluate the applicability and accuracy of the constitutive model.