Numerical calculation of fluid flows at arbitrary mach number

2008 ◽  
pp. 447-451 ◽  
Author(s):  
Francis H. Harlow ◽  
Anthony A. Amsden ◽  
Cyril W. Hirt
Keyword(s):  
Numerical Calculation ◽  
Mach Number ◽  
Fluid Flows

scholarly journals Study on the influence of radius of curvature on flow resistance in spiral pipe

2021 ◽  
Vol 237 ◽  
pp. 03013
Author(s):  
Wenqiang Li ◽  
Hui Qi ◽  
Yongfeng Yang ◽  
Guojun Zhao ◽  
Rong Liu ◽  
...  
Keyword(s):  
Numerical Calculation ◽  
Wind Speed ◽  
Flow Resistance ◽  
Fluid Flows ◽  
Radius Of Curvature ◽  
Curvature Radius ◽  
Change Rate ◽  
Linear Pattern ◽  
Offset Distance ◽  
Numerical Calculation Method

With the continuous development of west of China, a new kind of tunnel, namely spiral tunnel, has appeared in the expressway. Due to the special linear pattern, the resistance of airflow in spiral tunnel has been found to change, but there are few relevant researches at present. Therefore, numerical calculation method is used to study the variation of flow resistance in spiral pipe with different curvature. The results show that when the fluid flows in the spiral pipe, the wind speed is not uniformly distributed. The highest speed is not in the center of the pipe, but on the outside of the pipe, and the offset distance decreases with the increase of the radius of curvature. In addition, the change of flow resistance in spiral pipe is studied, and it is found that the change rate of flow resistance decreases with the increase of curvature radius. It shows that the radius of curvature is negatively correlated with the flow resistance.

Amplification of Operational Uncertainty Induced by Nonideal Flows in Supersonic Turbine Cascades

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Alessandro Romei ◽  
Davide Vimercati ◽  
Alberto Guardone ◽  
Giacomo Persico
Keyword(s):  
Mach Number ◽  
Incidence Angle ◽  
Fluid Flows ◽  
Expansion Process ◽  
Thermodynamic Critical Point ◽  
Nonideal Gas ◽  
Organic Rankine Cycles ◽  
Total State ◽  
Nonmonotonic Variation ◽  
Organic Fluids

Abstract In high-temperature transcritical organic Rankine cycles (ORCs), the expansion process may take place in the neighborhood of the thermodynamic critical point. In this region, many organic fluids feature a value of the fundamental derivative of gas dynamics Γ that is less than unity. As a consequence, severe nonideal gas-dynamic effects can be possibly observed. Examples of these nonideal effects are the nonmonotonic variation of the Mach number along an isentropic expansion, oblique shocks featuring an increase of the Mach number, and a significant dependence of the flow field on the upstream total state. To tackle this latter nonideal effect, an uncertainty-quantification strategy combined with Reynolds-averaged flow simulations is devised to evaluate the turbine performance in presence of operational uncertainty. The results clearly indicate that a highly nonideal expansion process leads to an amplification of the operational uncertainty. Specifically, given an uncertainty in the order of 1% in cycle nominal conditions, the mass flow rate and cascade losses vary ±4% and ±0.75 percentage points, respectively. These variations are four and six times larger than those prompted by an ideal-like expansion process. The flow delivered to the first rotating cascade is severely altered as well, leading to local variations in the rotor incidence angle up to 10 deg. A decomposition of variance contributions reveals that the uncertainty in the upstream total temperature is mainly responsible for these variations. Finally, the understanding of the physical mechanism behind these changes allows us to generalize the present findings to other organic-fluid flows.

Numerical calculation of internal wave motions

1972 ◽  
Vol 56 (2) ◽  
pp. 265-276 ◽  
Author(s):  
James A. Young ◽  
C. W. Hirt
Keyword(s):  
Experimental Data ◽  
Numerical Calculation ◽  
Finite Difference ◽  
Incompressible Fluid ◽  
Internal Wave ◽  
Fluid Flows ◽  
Two Dimensional ◽  
Finite Difference Technique ◽  
Small Density ◽  
Incompressible Fluid Flows

A finite-difference technique for the numerical calculation of two-dimensional stratified incompressible fluid flows is presented. Small density variations are not assumed, so that this method is generally applicable to a wide variety of problems. To illustrate this new technique a calculation has been made of the collapse of a uniformly mixed region in a linearly stratified fluid. In addition to giving excellent agreement with experimental data, the calculations also reveal the mechanism for an observed change in scaling behaviour.

Study of the Influence of Labyrinth Seal Clearance on Gearbox Leakage with Gas-Fluid Two-Phase Mixture

2015 ◽  
Vol 789-790 ◽  
pp. 231-235 ◽  
Author(s):  
Wei Dong He ◽  
Chen Wang ◽  
Ying Hui Zhang
Keyword(s):  
Numerical Calculation ◽  
Fluid Flows ◽  
Labyrinth Seal ◽  
Grid Size ◽  
Two Dimensional ◽  
Two Phase ◽  
Mixture Flow ◽  
Fluent Software ◽  
Phase Mixture ◽  
Gap Width

Established two-dimensional axisymmetric staggered tooth shape labyrinth seal grid model by GAMBIT software, simulated oil-air two-phase mixture flow field within labyrinth seal by fluent software, confirmed the best grid size of numerical calculation, studied the seal mechanism and influence of gap width variation on the leakage. The results show that when fluid flows through the narrow clearance, its velocity increases and pressure decreases. The optimized clearance width within 0.5mm to 1.0mm is preferable.

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