Analysis of Variable Fluid Properties, Turbulent Annular Seals

1991 ◽  
Vol 113 (4) ◽  
pp. 694-702 ◽  
Author(s):  
Luis A. San Andres
Keyword(s):  
Space Shuttle ◽  
Power Level ◽  
Fluid Motion ◽  
Dynamic Force ◽  
Computationally Efficient ◽  
Roughness Effects ◽  
Reference Case ◽  
Numerical Predictions ◽  
Fluid Properties ◽  
Cryogenic Liquids

A computational analysis for calculation of the dynamic force response in turbulent flow annular pressure seals of arbitrary nonuniform clearance is presented. Cryogenic liquids are considered as barotropic. The fluid motion is described by a bulk flow model and Moody’s friction factor is introduced to accomodate surface roughness effects. The numerical solution scheme is computationally efficient and accurate for seal operation at arbitrary eccentricity ratios. Numerical predictions show good agreement with available experimental results. The effects of eccentricity and liquid properties on the performance of the Space Shuttle Main Engine High Pressure Fuel Turbopump interstage seal at full power level are discussed as a reference case.

scholarly journals Investigation of Rotor Blade Roughness Effects on Turbine Performance

1992 ◽  
Author(s):  
J. L. Boynton ◽  
R. Tabibzadeh ◽  
S. T. Hudson
Keyword(s):  
Surface Finish ◽  
Space Shuttle ◽  
Power Level ◽  
Rotor Blades ◽  
Machining Process ◽  
Inlet Temperature ◽  
Test Results ◽  
Roughness Effects ◽  
Turbine Efficiency ◽  
Swirl Angle

The cold air test program was completed on the SSME (Space Shuttle Main Engine) HPFTP (High Pressure Fuel Turbopump) turbine with production nozzle vane rings and polished coated rotor blades with a smooth surface finish of 30 microinch (0.76 micrometer) RMS (Root Mean Square). The smooth blades were polished by an abrasive flow machining process. The test results were compared with the air test results from production rough coated rotor blades with a surface finish of up to 400 microinch (10.16 micrometer) RMS. Turbine efficiency was higher for the smooth blades over the entire range tested. Efficiency increased 2.1 percentage points at the SSME 104 percent RPL (Rated Power Level) condition. This efficiency improvement could reduce the SSME HPFTP turbine inlet temperature by 57 degrees Rankine (32 degrees Kelvin) increasing turbine durability. The turbine flow parameter increased and the mid-span outlet swirl angle became more axial with the smooth rotor blades.

scholarly journals Investigation of Rotor Blade Roughness Effects on Turbine Performance

1993 ◽  
Vol 115 (3) ◽  
pp. 614-620 ◽  
Author(s):  
J. L. Boynton ◽  
R. Tabibzadeh ◽  
S. T. Hudson
Keyword(s):  
Surface Finish ◽  
Space Shuttle ◽  
Power Level ◽  
Rotor Blades ◽  
Machining Process ◽  
Inlet Temperature ◽  
Test Results ◽  
Roughness Effects ◽  
Turbine Efficiency ◽  
Swirl Angle

The cold air test program was completed on the SSME (Space Shuttle Main Engine) HPFTP (High-Pressure Fuel Turbopump) turbine with production nozzle vane rings and polished coated rotor blades with a smooth surface finish of 30 μin. (0.76 μm) rms (root mean square). The smooth blades were polished by an abrasive flow machining process. The test results were compared with the air test results from production rough-coated rotor blades with a surface finish of up to 400 μin. (10.16 μm) rms. Turbine efficiency was higher for the smooth blades over the entire range tested. Efficiency increased 2.1 percentage points at the SSME 104 percent RPL (Rated Power Level) conditions. This efficiency improvement could reduce the SSME HPFTP turbine inlet temperature by 57 R (32 K), increasing turbine durability. The turbine flow parameter increased and the midspan outlet swirl angle became more axial with the smooth rotor blades.

Morphological effects of a hydraulic lifting dam on the middle Fenhe River, China

2021 ◽  
Author(s):  
Yufang Ni ◽  
Zhixian Cao ◽  
Wenjun Qi ◽  
Xiangbin Chai ◽  
Aili Zhao
Keyword(s):  
Shallow Water ◽  
General Pattern ◽  
Water Storage ◽  
Main Channel ◽  
Environmental Restoration ◽  
Two Dimensional ◽  
Compound Channel ◽  
Computationally Efficient ◽  
Bed Deformation ◽  
Numerical Predictions

<p>Hydraulic lifting dams become increasingly popular in China for water storage, river landscaping and environmental restoration. Inevitably, dams influence riverine morphology. Unfortunately, current understanding of this topic has remained rather limited. Here, the morphological effects of a hydraulic lifting dam on the middle Fenhe River, China are investigated. This reach features a compound channel and floodplains, and the riverbed is mainly composed of silt that can be easily eroded, indicating potential significant bed deformation. A computationally efficient depth-averaged two-dimensional shallow water hydro-sediment-morphodynamic model is employed. Unstructured meshes are refined around dam structures to accurately present topography. The numerical predictions show discrepancies of morphological responses of the main channel and floodplains to different operation schemes of the hydraulic lifting dam. This work helps to support decisions on the management of hydraulic lifting dams on the middle Fenhe River and reveals a general pattern for the morphological impact of hydraulic lifting dam.</p>

SIMULATION OF THE ALCOHOL-OIL MIXTURE IN A T-SHAPED MICROCHANNEL USING THE DISSIPATIVE PARTICLE DYNAMICS METHOD ON GPU DEVICES

2014 ◽  
Vol 13 (1) ◽  
pp. 65
Author(s):  
A. A. Horta ◽  
L. O. S. Ferreira ◽  
E. L. Martinez ◽  
R. Maciel Filho
Keyword(s):  
Dissipative Particle Dynamics ◽  
Fluid Motion ◽  
Particle Dynamics ◽  
Immiscible Fluids ◽  
Biodiesel Production ◽  
Model Parameters ◽  
Processing Unit ◽  
Fluid Properties ◽  
Practical Engineering ◽  
Multiphase Fluid

Multiphase fluid motion in microchannnels involves complicated fluid dynamics and is fundamentally important to diverse practical engineering applications. Among several applications, the alcohol-oil mixture is particularly important due to its application for biodiesel production. In this work, the mixture of immiscible fluids alcohol-oil in a square T-shaped microchannel was investigated using the Dissipative Particle Dynamics (DPD) method available in the HOOMD simulator, which runs on a single graphic processing unit (GPU). The immiscible fluids were achieved by increasing the repulsive force between species. The fluid properties and hydrodynamic behavior were discussed in function of model parameters. The simulation results agree with data published in the literature showing that the DPD is appropriate for simulation of mass transport on complex geometries in microscale on a single GPU.

Numerical analysis of factors influencing thermal effects generated by cavitation flow of cryogenic fluids

2020 ◽  
Vol 34 (17) ◽  
pp. 2050184 ◽  
Author(s):  
Suguo Shi ◽  
Guoyu Wang
Keyword(s):  
Thermal Effect ◽  
Liquid Nitrogen ◽  
Thermal Effects ◽  
Dynamic Pressure ◽  
Density Ratio ◽  
Cavitation Flow ◽  
Cryogenic Fluids ◽  
Factors Influencing ◽  
Fluid Properties ◽  
Cryogenic Liquids

Thermal effects dramatically impact on the cavitation dynamics of cryogenic fluids. Thus, to study the thermal effect factors influencing cryogenic cavitation, numerical simulations were conducted considering an axisymmetric ogive and a 2D quarter caliber hydrofoil in liquid nitrogen and hydrogen, respectively. The modified Merkle cavitation model and filter-based turbulence model were applied to account for the thermodynamic properties of the fluid. The energy equation was modified considering the cavitation phase change effects. Compared to the experimental data, the numerical method satisfactorily predicts the cryogenic cavitation flows. Based on the numerical results, the thermal effect characteristics in the cavitation flow of cryogenic fluids were investigated. The thermal effects in cryogenic cavitation is obvious when vapor content in constant location is considerably low, where the cavity becomes more porous and the interface becomes less distinct. The factors influencing the thermal effects in cavitation such as the temperature, fluid type and velocity were analyzed. Findings showed that thermal effects of cavitation were prominent around the critical temperature of cryogenic liquids. Compared to the thermal effects in liquid nitrogen, those in liquid hydrogen were more distinct because of the changes in the density ratio, vapor pressure and other fluid properties. When the flow velocity is higher, the thermal effects of cavitation are suppressed as the pressure depression caused by evaporation is much smaller than the dynamic pressure.

Application of the 3ω Hot Wire Technique for Measurement of Fluid Thermophysical Properties

2007 ◽  
Author(s):  
Brandon W. Olson ◽  
Ali Fahham
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Analytical Model ◽  
Thermophysical Properties ◽  
Fluid Motion ◽  
Hot Wire ◽  
Resistance Thermometer ◽  
Bulk Fluid ◽  
Radiation Losses ◽  
Fluid Properties

The popular 3ω method of measuring thermophysical properties of solids is adapted for the simultaneous measurement of thermal conductivity and heat capacity in both liquids and gases. This technique is experimentally simple and has a lower susceptibility to random experimental noise, bulk fluid motion, radiation losses, and non-linear effects than other transient hot wire measurement methods. The compactness of the 3ω hotwire allows it to be used with different fluids in a variety of circumstances with very little specialized experimental equipment. Both the experimental setup and theoretical model are detailed. Experimental 3ω measurements were made in a variety of common fluids (air, water, and mineral oil) using commercially drawn 10μm platinum and 5μm tungsten hot wires which serve as both heating element and resistance thermometer. Measurements taken over a range of frequencies are numerically reduced to provide both thermal conductivity and heat capacity information. Experimental measurements and the corresponding analytical model are presented in terms of impedance or thermal resistance; a more physically meaningful and intuitive basis of comparison. Fluid properties are determined by curve-fitting an analytical model to experimental data using a least-squares approach. This technique allows both thermal conductivity and heat capacity (or thermal diffusivity) to be uniquely determined from a single measurement sequence.

scholarly journals Development of a semi-Lagrangian advection scheme for the NEMO ocean model (3.1)

2020 ◽  
Vol 13 (9) ◽  
pp. 4379-4398
Author(s):  
Christopher Subich ◽  
Pierre Pellerin ◽  
Gregory Smith ◽  
Frederic Dupont
Keyword(s):  
Ocean Circulation ◽  
Fluid Motion ◽  
Ocean Model ◽  
Global Ocean ◽  
Test Case ◽  
Courant Number ◽  
Time Step ◽  
Fluid Properties ◽  
Grid Points ◽  
Lagrangian Advection

Abstract. As resolutions of ocean circulation models increase, the advective Courant number – the ratio between the distance travelled by a fluid parcel in one time step and the grid size – becomes the most stringent factor limiting model time steps. Some atmospheric models have escaped this limit by using an implicit or semi-implicit semi-Lagrangian formulation of advection, which calculates materially conserved fluid properties along trajectories which follow the fluid motion and end at prescribed grid points. Unfortunately, this formulation is not straightforward in ocean contexts, where the irregular, interior boundaries imposed by the shore and bottom orography are incompatible with traditional trajectory calculations. This work describes the adaptation of the semi-Lagrangian method as an advection module for an operational ocean model. We solve the difficulties of the ocean's internal boundaries by calculating parcel trajectories using a time-exponential formulation, which ensures that all parcel trajectories remain inside the ocean domain despite strong accelerations near the boundary. Additionally, we derive this method in a way that is compatible with the leapfrog time-stepping scheme used in the NEMO-OPA (Nucleus for European Modelling of the Ocean, Océan Parallélisé) ocean model, and we present simulation results for a simplified test case of flow past a model island and for 10-year free runs of the global ocean on the quarter-degree ORCA025 grid.

Economic Potential of Innovative Receiver Concepts With Different Solar Field Configurations for Supercritical Steam Cycles

2011 ◽  
Author(s):  
Cs. Singer ◽  
R. Buck ◽  
R. Pitz-Paal ◽  
H. Mu¨ller-Steinhagen
Keyword(s):  
Molten Salt ◽  
Cost Reduction ◽  
Reduction Potential ◽  
Power Level ◽  
Direct Absorption ◽  
Reference Case ◽  
Levelized Cost Of Electricity ◽  
Absorber Structure ◽  
Solar Field ◽  
Lateral Area

The cost reduction potential of solar power towers (SPT) is an important issue concerning its market introduction. Raising the steam process temperature and pressure can lead to a cost reduction due to increased overall plant efficiency. Thus, for new receiver configurations a supercritical steam cycle operated at 300 bar / 600°C / 610°C live steam conditions was assumed. The considered systems include innovative direct absorption receivers, either with conventional or beam down heliostat field layouts. For the beam down option the receiver is assumed to be a cylindrical vessel with a flow-through porous absorber structure at the internal lateral area of the cylinder. The direct absorption receiver option consists of a cylindrical barrel with downwards oriented aperture, whose absorber structure at the internal lateral area is cooled by a molten salt film. For the assessment, CFD based methods were developed to be able to examine the receiver efficiency characteristics. Based on the receiver thermal efficiency characteristics and the solar field characteristics the annual performance is evaluated using hourly time series. The assessment methodology is based on the European Concentrated Solar Thermal Roadmap (ECOSTAR) study and enables the prediction of the annual performance and the levelized cost of electricity (LCOE). Applying appropriate cost assumptions from literature the LCOE were estimated for each considered SPT concept and compared to tubular receiver concepts with molten salt and liquid metal cooling. The power level of the compared concepts and the reference case is 200 MWel. The sensitivity of the specific cost assumptions was analyzed. No detailed evaluation was done for the thermal storage, but comparable storage utilization and costs were assumed for all cases. At optimized plant parameters the results indicate a LCOE reduction potential of up to 0.5% for beam down and of up to 7.2% for the direct absorption receiver compared to today’s state of the art molten salt solar tower technology.

Parallelization of LBM Code Using CUDA Capable GPU Platform for 3D Single and Two-Sided Non-Facing Lid-Driven Cavity Flow

2011 ◽  
Author(s):  
Muhammad S. Alam ◽  
Liang Cheng
Keyword(s):  
Numerical Algorithms ◽  
Cavity Flow ◽  
Lattice Boltzmann Model ◽  
Computationally Efficient ◽  
Driven Cavity ◽  
Flow Problems ◽  
Device Architecture ◽  
Numerical Predictions ◽  
Driven Cavity Flow ◽  
Nvidia Gpu

In this paper, a lattice Boltzmann model is developed and then parallelized employing a Compute Unified Device Architecture (CUDA) capable nVIDIA GPU platform. Numerical algorithms are developed for the solution of 3D single and two-sided non-facing lid-driven (TSNFL) cavity flow for Re = 10–1000. The algorithms are verified by solving both steady and unsteady 3D cavity and 3D TSNFL flow problems. Excellent agreement is obtained between numerical predictions and results available in literature. The results show that the CUDA-enabled LBM code is computationally efficient. It is observed that the implementation of LBM on a GPU allows at least thirty million lattice updates per second for 3-D lid driven cavity flow. Computations have been carried out for a 2-D lid driven cavity flow too. It is revealed that LBM-GPU calculation achieves 641 million lattice updates per second for the 2-D lid driven cavity flow.

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