Effects of acoustic disturbances on measured flow characteristics through a contraction

AIAA Journal ◽  
1987 ◽  
Vol 25 (5) ◽  
pp. 659-667 ◽  
Author(s):  
J. Tan-atichat ◽  
S. Harandi
Keyword(s):  
Flow Characteristics ◽  
Acoustic Disturbances ◽  
Measured Flow

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.

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.

Experimental and Numerical Investigation of Flow Characteristics Near Casing in an Axial Flow Compressor Rotor at Stable and Stall Inception Conditions

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Yanhui Wu ◽  
Junfeng Wu ◽  
Gaoguang Zhang ◽  
Wuli Chu
Keyword(s):  
Flow Field ◽  
Flow Characteristic ◽  
Flow Characteristics ◽  
Axial Flow ◽  
Stall Inception ◽  
Axial Flow Compressor ◽  
Compressor Rotor ◽  
Instantaneous Flow Field ◽  
Measured Flow ◽  
Flow Compressor

Casing instantaneous pressure measurements and full-annulus unsteady simulations were undertaken to analyze flow characteristics near casing at stable and stall inception conditions in an axial flow compressor rotor, and the objective was to establish its linkage with the stall inception process. The measured flow characteristic at near-stall stable operating conditions was the appearance of rotating instability (RI), which attributed to the activity of an unsteady flow with varying frequency. A similar flow characteristic was found in the simulated near-stall stable flow conditions, and detailed analyses of instantaneous flow field indicated the formation and activity of tip secondary vortex could be flow mechanism for the appearance of RI as far as nonuniform tip loading distribution in measurements was concerned. The measured flow characteristic before spike emergence was still the activity of RI. However, it was submerged into flow field accompany by the emergence of spike. The simulated stall inception process was similar to that from measurement, and further analyses of instantaneous flow field established the causal linkage between RI and stall inception process for the test rotor.

scholarly journals Flow Characteristics of a Highly Rotating Turbine Cavity System With Discharge Hole

1999 ◽  
Author(s):  
D. J. Maeng ◽  
J. S. Lee ◽  
R. Jakoby ◽  
S. Kim ◽  
S. Wittig
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Rotational Velocity ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Rotating Disk ◽  
Disk System ◽  
High Speed Rotation ◽  
Measured Flow ◽  
Cavity System

An experimental investigation is performed to analyze the flow characteristics of a turbine cavity system containing discharge holes installed in a rotating disk. The turbine cavity system is composed of a rotating disk and two stationary disks on both sides of the rotating disk. The air flow is induced into the upstream cavity, and then discharged into the downstream cavity through 8 discharge holes in the rotating disk. The flow field in each cavity at high-speed rotation of the rotor was measured by a three-dimensional LDV system. The measured flow field is analyzed to understand the flow structures, and further provide information for studying the heat transfer behaviors of the turbine disk system. The overall flow field in the upstream cavity shows a negligible axial velocity with a relatively small rotational velocity, less than 10% of the rotor speed. The downstream cavity flow has a high rotational velocity close to the rotational speed of the discharged jets, due to the direct circumferential momentum transfer from the discharged jets. The interaction between the discharged jet and the downstream stator disk induces an asymmetric development of the spreading wall jet, which results in a relative circumferential motion to the revolving discharged jet. The whole flow field in the downstream cavity is divided into several flow regions according to their features.

Exploring and Improving the Flow Characteristics of an Empty Water Channel Test Section: The Application of TomoPIV and Flowrate Sensors for Whole-Flow-Field Visualization

2019 ◽  
Author(s):  
Seyedmohammad Mousavi sani ◽  
Navid Goudarzi ◽  
Mohammadamin Sheikhshahrokhdehkordi ◽  
Tucker Bisel ◽  
Jerry Dahlberg ◽  
...  
Keyword(s):  
Flow Field ◽  
Flow Velocity ◽  
Test Section ◽  
Water Channel ◽  
Flow Characteristics ◽  
Flow Speed ◽  
Mean Velocity ◽  
Measurement Volume ◽  
Measured Flow ◽  
Field Velocity

Abstract This paper presents the quantitative results of improving the uniformity of the flow field within the test section of a constant cross section, closed-loop water channel. Tomographic Particle Image Velocimetry (TomoPIV) and four flowrate sensors are used to determine the mean velocity and velocity fluctuations at two motor frequencies: 7.5 Hz and 10 Hz (an approximate free stream flow velocity of 0.11 m/s and 0.18 m/s, respectively). The flow field velocity determined by the flowrate sensors showed great agreements with the TomoPIV results. For instance, at the 10 Hz water channel motor frequency, the flowrate sensors and TomoPIV obtained velocity ranges of 0.191–0.202 m/s and 0.185–0.21 m/s, respectively. In order to reduce the flow speed variations within the studied TomoPIV measurement volume, improvements were implemented on the water channel to include an adjustable screen and deflector to the first set of turning vanes downstream from the water channel motor. The modification improved the 7.5 Hz motor frequency measured flow velocity from 0.16–0.172 m/s to 0.106–0.108 m/s resulting in a final variation of flow speed within the measurement volume reduced to 1%.

Cooling Heat Transfer and Flow Characteristics of Carbon Dioxide and Lubricant Mixtures in Supercritical Pressure Conditions

2006 ◽  
Author(s):  
Koji Mori ◽  
Kunihiro Shimoki ◽  
Hirokazu Shimaoka ◽  
Junji Onishi
Keyword(s):  
Heat Transfer ◽  
Flow Pattern ◽  
Flow Characteristics ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Mass Fluxes ◽  
Lubricant Flow ◽  
Measured Flow ◽  
Visualization Experiments ◽  
Air Conditioning Systems

In order to obtain the data for designing and optimizing air conditioning systems using a CO2 refrigerant, the cooling heat transfer characteristics of CO2-lubricant mixtures were experimentally examined. The experiments were carried out under the CO2 mass fluxes of 100 - 500 kg/(m2s) and oil concentrations of 0 - 13 % at the pressure of 9.5MPa. The obtained data revealed that heat transfer coefficients of the mixtures were approximately 0.3 - 0.85 times as much as those of only CO2. In order to clarify the effects of the lubricant, flow visualization experiments were carried out and the obtained information revealed that there appeared two types of flow patterns, stratified flow and annular flow. Furthermore, it was also found that in the lubricant concentration range of 3-5 %, the heat transfer coefficients decreased about 25 % in separated flows, and about 70% in annular flows. For estimating flow pattern, already published well-known flow pattern maps were examined whether those maps were consistent with the measured flow pattern data and it was found that no map was available. A new flow pattern map was proposed for CO2-lubricant mixtures.

Effects of Stream Turbulence on Free Shear Flows

1978 ◽  
Vol 29 (1) ◽  
pp. 33-43 ◽  
Author(s):  
Rajni P. Patel
Keyword(s):  
Experimental Investigation ◽  
Boundary Layers ◽  
Shear Flows ◽  
Mixing Layer ◽  
Flow Characteristics ◽  
Initial Boundary ◽  
Turbulent Boundary Layers ◽  
Turbulent Shear ◽  
Plane Mixing Layer ◽  
Acoustic Disturbances

SummaryRecently attention has been given to the effects of the stream turbulence on the characteristics of the turbulent boundary layers and the turbulent shear flows. For the boundary layers considerable information on the effects of the stream turbulence is available but for the shear flows it is limited. This paper describes an experimental investigation for the effects of stream turbulence on the development of an asymmetric jet and a plane mixing layer. It is shown that the characteristics of these flows are considerably affected by the stream turbulence but for the measurements in the plane mixing layers at large downstream distances the influence of the stream turbulence is negligible provided the intensities are less than 0.6%. For the plane mixing layer the results show that the flow characteristics are not affected significantly by the initial boundary layers, the acoustic disturbances and the boundary conditions imposed by the end plates.

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