Experimental and Numerical Assessment of an Axial Piston Pump’s Speed Limit

2016 ◽  
Author(s):  
Markus Kunkis ◽  
Jürgen Weber
Keyword(s):  
Power Density ◽  
Flow Characteristics ◽  
Deep Understanding ◽  
Precise Determination ◽  
Maximum Pressure ◽  
Speed Limit ◽  
Flow Phenomena ◽  
Measured Flow ◽  
Flow Effects ◽  
Axial Piston

A high power density is a crucial requirement to axial piston pumps. It is determined by the machines’ maximum pressure and speed. At high rotational speeds, cavitation leads to the partial filling of the cylinders with gas and causes a breakdown of the delivery flowrate. A further increase of the speed limit requires a deep understanding of these effects. Since they are very hard to capture metroligically, power density has not significantly increased over the past 20 years. Recently, the steadily increasing availability of computational power has made possible the simulation, visualisation and analysis of the flow effects inside the pumps by means of computational fluid dynamics. In this paper, a criterion and a method for the precise determination of the pumps’ speed limit are presented. The description of the experimental setup is followed by flow characteristics measured at varying suction and delivery pressures. Afterwards, a CFD model of the pump is presented. It is shown how the measured flow characteristics can be reproduced in the simulation. The flow phenomena causing the speed-limiting cavitation effects are identified by a detailed analysis of the CFD results. Eventually, constructive countermeasures allowing increased rotational speeds and thereby power densities are proposed.

Magnetophoresis Effects on the Flow Characteristics of Oil-Based Ferrofluids in Rectangular Enclosures

2015 ◽  
Vol 15 (10) ◽  
pp. 7451-7456
Author(s):  
Hyeon-Seok Seo ◽  
Jin-Hyo Boo ◽  
Youn-Jea Kim
Keyword(s):  
Magnetic Fields ◽  
Permanent Magnet ◽  
Flow Characteristics ◽  
Flow Fields ◽  
Working Fluid ◽  
Magnetic Flux Density ◽  
Magnetic Field Direction ◽  
Analysis Model ◽  
Rectangular Enclosure ◽  
Flow Phenomena

This study numerically investigated the flow characteristics in a rectangular enclosure filled with oil-based ferrofluid (EFH-1, Ferrotec.) under the influence of external magnetic fields. The rectangular enclosure contained obstacles with different shapes, such as a rectangle and a triangle mounted on the top and bottom wall surfaces. In order to generate external magnetic fields, a permanent magnet was located in the lower part of the rectangular enclosure, and its direction was selected to be either horizontal or vertical. Our results showed that the ferrofluid flow fields were affected by the applied external magnetic field direction and eddy flow phenomena in the working fluid were generated in the vicinity of high magnetic flux density distributions, such as at the edge of the permanent magnet. It was also confirmed that the magnetophoretic force distributions in the analysis model played a significant role in the development of the ferrofluid flow fields.

Heat Transfer and Flow Phenomena in a Swirl Chamber Simulating Turbine Blade Internal Cooling

1998 ◽  
Author(s):  
C. R. Hedlund ◽  
P. M. Ligrani ◽  
H.-K. Moon ◽  
B. Glezer
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Internal Cooling ◽  
Vortex Pairs ◽  
Nusselt Numbers ◽  
Swirl Chamber ◽  
Flow Phenomena ◽  
Energy Balances

Heat transfer and fluid mechanics results are given for a swirl chamber whose geometry models an internal passage used to cool the leading edge of a turbine blade. The Reynolds numbers investigated, based on inlet duct characteristics, include values which are the same as in the application (18000–19400). The ratio of absolute air temperature between the inlet and wall of the swirl chamber ranges from 0.62 to 0.86 for the heat transfer measurements. Spatial variations of surface Nusselt numbers along swirl chamber surfaces are measured using infrared thermography in conjunction with thermocouples, energy balances, digital image processing, and in situ calibration procedures. The structure and streamwise development of arrays of Görtler vortex pairs, which develop along concave surfaces, are apparent from flow visualizations. Overall swirl chamber structure is also described from time-averaged surveys of the circumferential component of velocity, total pressure, static pressure, and the circumferential component of vorticity. Important variations of surface Nusselt numbers and time-averaged flow characteristics are present due to arrays of Görtler vortex pairs, especially near each of the two inlets, where Nusselt numbers are highest. Nusselt numbers then decrease and become more spatially uniform along the interior surface of the chamber as the flows advect away from each inlet.

Effect of Tube Diameter on Flow Phenomena of Gas-Liquid Two-Phase Flow in Microchannels

2015 ◽  
Author(s):  
Hideo Ide ◽  
Eiji Kinoshita ◽  
Ryo Kuroshima ◽  
Takeshi Ohtaka ◽  
Yuichi Shibata ◽  
...  
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Water Solution ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Tube Diameter ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Flow Phenomena ◽  
The Waves

Gas-liquid two-phase flows in minichannels and microchannels display a unique flow pattern called ring film flow, in which stable waves of relatively large amplitudes appear at seemingly regular intervals and propagate in the flow direction. In the present work, the velocity characteristics of gas slugs, ring films, and their features such as the gas slug length, flow phenomena and frictional pressure drop for nitrogen-distilled water and nitrogen-30 wt% ethanol water solution have been investigated experimentally. Four kinds of circular microchannels with diameters of 100 μm, 150 μm, 250 μm and 518 μm were used. The effects of tube diameter and physical properties, especially the surface tension and liquid viscosity, on the flow patterns, gas slug length and the two-phase frictional pressure drop have been investigated by using a high speed camera at 6,000 frames per second. The flow characteristics of gas slugs, liquid slugs and the waves of ring film are presented in this paper.

A New Concept of Externally Heated Engine—Comparisons with the Stirling Engine

1996 ◽  
Vol 210 (5) ◽  
pp. 363-371 ◽  
Author(s):  
L Brzeski ◽  
Z Kazimierski
Keyword(s):  
Low Power ◽  
Power Density ◽  
Internal Combustion Engines ◽  
Thermodynamic Cycle ◽  
Rotational Frequency ◽  
Stirling Engine ◽  
Maximum Pressure ◽  
Combustion Engines ◽  
Working Medium ◽  
Engine Cylinder

This paper presents a new concept of the externally heated valve (EHV) engine. Air can be used as a working medium in the closed cycle of this engine. Heat delivered to the working air can come from a combustion chamber or another heat generator of an arbitrary type. The engine construction and the thermodynamic cycle performed by it are original and entirely different from the well-known Stirling engine. The main disadvantage of the Stirling engine is its low power density, that is the low power obtained per litre of the engine cylinder volume. In the case of the engine presented here it is possible to achieve power density and efficiency similar to those typical of advanced internal combustion engines. Comparisons between the power of the Stirling engine and the power of the new engine have been performed for the same engine capacity, rotational frequency and maximum and minimum temperatures of the cycle. At the same minimum pressure of the working gas in both engines, the power of the EHV engine is several times higher than that of the Stirling engine, while, on the other hand, at the same maximum pressure of the working gas in both engines, the power of the EHV engine is 20 per cent higher than that of the Stirling engine power. The efficiencies of both engines do not differ significantly from each other.

scholarly journals Flow-Induced Vibration on the Control Valve with a Different Concave Plug Shape Using FSI Simulation

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Akram Zeid ◽  
Mohamed Shouman
Keyword(s):  
High Efficiency ◽  
Complex Structure ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Simulation ◽  
Control Valve ◽  
Low Noise ◽  
Flow Induced Vibration ◽  
Nonlinear Characteristics ◽  
Flow Phenomena

Control valves have always been recognised as being among the most crucial control equipment, commonly utilised in versatile engineering applications. Hence, the need has arisen to identify the flow characteristics inside the valve, together with the incurred vibration induced as a result of the flow passing through the valve. Thanks to the tangible and fast progress made in the field of the flow simulation and numerical techniques, it has become possible to better observe the behavior of the flow passing inside a valve with view to examining its performance. Hence, the paper at hand is mainly concerned with introducing the modeling and simulation of a control valve. On the contrary, the flow system in a control valve is marked by a complex structure and nonlinear characteristics. The reasons for those qualities could be attributed to its construction as well as the fluid flow phenomena associated with it. It is especially for the sake of investigating and observing the flow characteristics, pertaining to a control valve equipped with different concave plug shapes and different openings, that the three-dimensional FSI simulation is conducted. In addition, it would be possible to make use of the obtained results relating to the three-dimensional analysis to achieve low noise and high efficiency improvement. Furthermore, all results will be validated on experimental grounds.

Cuttings Characteristics and Mechanics Behavior in Horizontal Wells of Liaohe Oil Field

2013 ◽  
Vol 316-317 ◽  
pp. 842-845
Author(s):  
Xian Zhong Yi ◽  
Jun Feng Zhang ◽  
Sheng Zong Jiang
Keyword(s):  
Flow Characteristics ◽  
Oil Field ◽  
Cuttings Transport ◽  
Two Phase ◽  
Fluid Medium ◽  
Washing Process ◽  
Three Phase ◽  
Flow Phenomena ◽  
Phase Liquid ◽  
Cuttings Bed

Cuttings transport of drilling and washing process in horizontal well is a typical two-phase (liquid-solid) or three-phase (gas-liquid-solid) flow phenomena. In this paper, it analyzes the flow characteristics of Huan 127-Lian H2 horizontal wellbore , then uses experimental method to study the behavior of the particle size distribution and the mechanics. This study provides an important way to master cuttings settling in fluid medium, it can explain how the cuttings bed is generated and cleared, and why the procession of cuttings of migration is stopped. In addition, measurement and analysis of drill cuttings is the basis erosion and abrasion analysis of BHA.

Enhancing the Centrifugal Compressor Performance Map Measurements Through a Developed One–Dimensional Calculation Tool to Analyse Local Flow Phenomena

2014 ◽  
Author(s):  
Matthias Hamann ◽  
Elias Chebli ◽  
Markus Müller ◽  
Alexander Krampitz
Keyword(s):  
Centrifugal Compressor ◽  
Static Pressure ◽  
Flow Characteristics ◽  
Local Flow ◽  
One Dimensional ◽  
Casing Treatment ◽  
Surge Margin ◽  
Performance Map ◽  
Flow Phenomena ◽  
Compressor Performance

Centrifugal compressors for automotive turbochargers have large influence on the operation characteristic of combustion engines. Especially the improvement of the surge margin is one of the most important development targets. Thereby, a reliable detection of local flow phenomena within the compressor stage is necessary and a procedure to gain this information from standard measurement data is discussed in this paper. A one–dimensional calculation methodology for a single-stage centrifugal compressor with a vaneless diffuser and casing treatment is presented. The tool calculates the flow properties at the impeller inlet and exit as well as at diffuser exit, based on the measured inlet and outlet data and the geometry information of the compressor. The calculated flow characteristics are plotted within the measured compressor performance map to show local flow parameters. The unsteady recirculation flow within the casing treatment, the inflow angle and the total pressure losses are considered. The tool is validated on different compressor sizes. Thereby the compressor is equipped with static pressure measuring points at the impeller inlet and exit as well as at the diffuser exit. The calculated static pressure correlated well with the measured data with an accuracy of 2 % to 5 % on 95 % of the operating range. In this paper an experimental parameter study is executed in order to improve the surge margin. Thereby the geometry of the diffuser and the casing treatment is varied and the compressor performance is measured on a turbocharger test rig. The calculation of the flow angles and other flow characteristics within the diffuser enables one to find out whether surge is triggered through the diffuser or the impeller.

A Device for Measuring Thin Fluid Flow Depth Over an Inclined Open Rectangular Channel

2009 ◽  
Vol 131 (10) ◽  
Author(s):  
A. K. Majumder
Keyword(s):  
Fluid Flow ◽  
Flow Behavior ◽  
Rectangular Channel ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Multiple Point ◽  
Flow Depth ◽  
Flow Rates ◽  
Law Of The Wall ◽  
Measured Flow

Accurate knowledge of the fluid flow depth over an inclined rectangular open channel is of obvious value in the modeling of flow characteristics over that channel. Understanding of this type of fluid flow behavior is of immense importance to the mineral processing fraternity as a large number of separators work on this principle. Therefore, a multiple point computer-controlled depth gauge was developed to measure water flow depths at various flow rates ranging from 0.81 l/s to 2.26 l/s over an inclined (17.5 deg) rectangular channel (2400 mm long and 370 mm wide). This paper describes the details about the device and the data acquisition procedure. An attempt has also been made to predict the measured flow depths at various operating conditions by using a modified form of the conventional law of the wall model. An overall relative error of 4.23% between the measured and the predicted flow depths at various flow rates establishes the validity of the model.

Correlations of the Holdup and the Frictional Pressure Drop in Air-Water Two-Phase Flow in a Flat Capillary Rectangular Channel

2004 ◽  
Author(s):  
Hideo Ide ◽  
Tohru Fukano
Keyword(s):  
Pressure Drop ◽  
Aspect Ratio ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Two Phase Flows ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Flow Phenomena

Both vertical upward and horizontal gas-liquid two-phase flows in a flat capillary rectangular channel were studied to clarify the flow phenomena, the holdup and the frictional pressure drop. The dimension of the channel used was 9.9 mm × 1.1 mm. The orientations of the channel were with the wide side vertical and the wide side horizontal. The differences between the flow characteristics in such orientations were investigated. New correlations of holdup and frictional pressure drop for flat capillary channels are proposed, in which the effect of aspect ratio has been taken into consideration.

Modeling and Analysis of Main Flow–Shroud Leakage Flow Interaction in LP Turbines

2006 ◽  
Author(s):  
Jochen Gier ◽  
Karl Engel ◽  
Bertram Stubert ◽  
Ralf Wittmaack
Keyword(s):  
Main Flow ◽  
Navier Stokes ◽  
Aerodynamic Load ◽  
Leakage Flow ◽  
Modeling And Analysis ◽  
Simplified Approach ◽  
Leakage Flows ◽  
Flow Phenomena ◽  
Flow Effects ◽  
The Impact

Endwall losses significantly contribute to the overall losses in modern turbomachinery, especially when aerodynamic load and pressure ratios are increased. In turbines with shrouded airfoils a large portion of these losses are generated by the leakage flow across the shroud clearance. For the design of modern jet engine turbines it becomes increasingly important to include the impact of shroud leakage flows in the aerodynamic design. There are two main aspects connected to this issue. The first aspect is to optimize the cavity flow and its interaction with the main flow. The second aspect is to perform the airfoil design with boundary conditions, which include the shroud leakage flow effects. In comparison to the simplified approach of neglecting the real endwall geometry and leakage flow this should enable the designer to produce improved airfoils for the entire span. In order to address the second aspect of supporting the airfoil design with improved shroud leakage consideration within the airfoil design process, an efficient procedure for modeling the shroud leakage flow has been implemented into the design Navier-Stokes code. The intention is to model the major leakage flow phenomena without the necessity of pre-defining all details of the shroud geometry. In the paper the results of this model are compared to conventional computations, computations with mesh-resolved cavities and experimental data. The differences are discussed and the impact of certain configuration aspects are analyzed.

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