Erratum: “Numerical Investigations of Pressure Distribution Inside a Ventilated Supercavity” [ASME J. Fluids Eng., 2017, 139(2), p. 021301; DOI: 10.1115/1.4035027]

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Lei Cao ◽  
Ashish Karn ◽  
Roger E. A. Arndt ◽  
Zhengwei Wang ◽  
Jiarong Hong
Keyword(s):  
Pressure Distribution ◽  
Numerical Investigations ◽  
Ventilated Supercavity

Experimental and Numerical Investigations of Flowpath Profiling on Secondary Flow Losses in a Turbine Control Stage

2013 ◽  
Author(s):  
Nils Moser ◽  
Peter Steinhoff ◽  
Franz Joos
Keyword(s):  
Pressure Distribution ◽  
Secondary Flow ◽  
Guide Vane ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Formation Mechanisms ◽  
Guide Vanes ◽  
Numerical Investigations ◽  
Control Stage ◽  
Wide Range

The numerically and experimentally investigated industrial steam turbine control stage is derived from a real design. Due to the production process and costs of the guide vanes for control stages of steam turbines the flowpath profiling is rotationally symmetric. However the combination of the two-dimensional shroud contour and the flow deflection in the guide vane results in a fully three-dimensional end wall contour having a strong influence on the secondary flow features in the turbine control stage. To obtain an improved profile for the nozzle shroud the reduction of the total pressure loss over the guide vanes is taken as an optimization criterion. The three-dimensional contour generates a diffuser flowpath between the suction and the pressure side of two guide vanes perpendicular to the main flow direction. This diffuser geometry affects the pressure distribution over the guide vane and therefore the formation mechanisms of secondary flows. For the experimental and numerical investigations a baseline shroud design and two additional profiled contours are analyzed in detail. The control stage test rig is operated with air and is capable to represent a wide range of operating conditions. The measurements show a considerable increase of the stage efficiency and power output. The effect of the flowpath profiling on the pressure distribution over the guide vane is clearly proved.

Numerical Investigations of Pressure Distribution Inside a Ventilated Supercavity

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Lei Cao ◽  
Ashish Karn ◽  
Roger E. A. Arndt ◽  
Zhengwei Wang ◽  
Jiarong Hong
Keyword(s):  
Pressure Gradient ◽  
Internal Pressure ◽  
Pressure Distribution ◽  
Numerical Study ◽  
Adverse Pressure Gradient ◽  
Air Entrainment ◽  
Gravitational Effect ◽  
Surface Model ◽  
Multiphase Model ◽  
Ventilated Supercavity

A numerical study has been conducted on the internal pressure distribution of a ventilated supercavity generated from a backward facing cavitator under different air entrainment coefficients, Froude numbers, and blockage ratios. An Eulerian multiphase model with a free surface model is employed and validated by the experiments conducted at St. Anthony Falls Laboratory of the University of Minnesota. The results show that the internal pressure in the major portion of the supercavity is primarily governed by the hydrostatic pressure of water, while a steep adverse pressure gradient occurs at the closure region. Increasing the air entrainment coefficient does not largely change the pressure distribution, while the cavity tail extends longer and consequently the pressure gradient near the closure decreases. At smaller Froude number, there is a more pronounced gravitational effect on the supercavity with increasing uplift of the lower surface of the cavity and a decreasing uniformity of the pressure distribution in the supercavity. With the increase of blockage ratio, the overall pressure within the supercavity decreases as well as the pressure gradient in the main portion of the supercavity. The current study shows that the assumption of uniform pressure distribution in ventilated supercavities is not always valid, especially at low Fr. However, an alternative definition of cavitation number in such cases remains to be defined and experimentally ascertained in future investigations.

Experimental and Numerical Investigations of Turbocharger Rotors on Full-Floating Ring Bearings With Circumferential Oil-Groove

2017 ◽  
Author(s):  
Ioannis Chatzisavvas ◽  
Gerrit Nowald ◽  
Bernhard Schweizer ◽  
Panagiotis Koutsovasilis
Keyword(s):  
Pressure Distribution ◽  
Thermal Energy ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Nonlinear Differential Equations ◽  
Equations Of Motion ◽  
Oil Viscosity ◽  
Hydrodynamic Bearing ◽  
Numerical Investigations ◽  
Run Up

This work presents experimental and numerical investigations into the vibrations of turbocharger rotors on full-floating ring bearings with a circumferential oil-groove. The pressure distribution in the fluid-film bearings is calculated through the Reynolds equation using a highly efficient global Galerkin approach with suitable trial and test functions. The numerical efficiency of the method is markedly increased as the resultant linear system is solved symbolically, establishing a semi-analytical solution. The temperature in the oil-film may increase due to the mechanical power dissipation, affecting the pressure distribution and the load capacity of the bearing. Therefore, a reduced thermal energy model is implemented together with the Reynolds equation to account for the variable oil-viscosity and for the thermal expansion of the surrounding solids. The thermal energy balance equations are implemented in a transient form, i.e. including the time dependent temperature term. The corresponding system of nonlinear differential equations is efficiently solved, leading to a further significant reduction in simulation times. The hydrodynamic bearing model including the thermal effects is finally coupled with the equations of motion of a turbocharger rotor and numerical run-up simulations are compared with experimental results. The comparisons show that the numerical model captures adequately the dynamics of the system, giving precise information about the frequencies and the amplitudes of the synchronous and the self-excited subsynchronous rotor vibrations.

scholarly journals Influence of Flow Field's Radial Dimension on Ventilated Supercavitating Flow

2020 ◽  
Vol 38 (3) ◽  
pp. 478-484
Author(s):  
Haiyu Xu ◽  
Kai Luo ◽  
Chuang Huang ◽  
Zhenhao Zuo
Keyword(s):  
Pressure Distribution ◽  
Maximum Diameter ◽  
Engineering Practice ◽  
Pronounced Increase ◽  
Gas Leakage ◽  
Calculation Results ◽  
Sst Turbulence Model ◽  
Radial Dimension ◽  
Ventilated Supercavity ◽  
Dimension Ratio

To investigate the influence of flow field's radial dimension on the flow of the portion gas-leakage supercavity, based on the two-fluid multiphase flow model and SST turbulence model, considering the compressibility of ventilated gas, a 3D simulation model of ventilated supercavity was established to simulate the flow of the supercavitation, which was consistent with water tunnel experiment. The effect of flow field's radial dimension on ventilated supercavity's dimension and pressure distribution was studied. The results show that flow field's radial dimension has a significant effect on the ventilated supercavity's dimension and pressure distribution. When flow field's radial dimension ratio is 6.5 times lower than the maximum diameter of supercavity, the supercavity cannot be formed to completely enclose the underwater vehicle. With the increase of flow field's radial dimension, the pressure inside and outside the supercavity decreases, and there is a pronounced increase in supercavity dimension. When flow field's radial dimension ratio is 54.0 times greater than the maximum diameter of supercavity, the dimension and pressure distribution of ventilated supercavity remain unchanged, which coincides with the theoretical results. In addition, the calculation results provide a criterion for simulating the shape of ventilated supercavity in the open environment, which can be used to guide engineering practice.

Experimental and numerical investigations of fluid flow in a hydrocyclone without an air core

CIM Journal ◽  
2017 ◽  
Vol 8 (1) ◽  
Author(s):  
E. Kucukal ◽  
J. R. Kadambi ◽  
J. Furlan ◽  
R. Visintainer
Keyword(s):  
Fluid Flow ◽  
Numerical Investigations ◽  
Air Core

EFFECTS OF AIR ON SPLASHING DURING A LARGE DROPLET IMPACT: EXPERIMENTAL AND NUMERICAL INVESTIGATIONS

2006 ◽  
Vol 16 (8) ◽  
pp. 981-996 ◽  
Author(s):  
Richard A. Jepsen ◽  
Sam S. Yoon ◽  
Byron Demosthenous
Keyword(s):  
Droplet Impact ◽  
Large Droplet ◽  
Numerical Investigations
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