Measurement of Intake Valve/Cylinder Boundary Flows Using a Multiple Orientation Hot-Wire Technique

1988 ◽  
Vol 110 (4) ◽  
pp. 361-366 ◽  
Author(s):  
T. C. Wagner ◽  
J. C. Kent
Keyword(s):  
Flow Direction ◽  
Sequential Sampling ◽  
Effective Area ◽  
Flow Speed ◽  
Intake Valve ◽  
Hot Wire ◽  
Mean Velocity ◽  
Local Flow ◽  
Discharge Coefficients ◽  
Velocity Magnitude

A new measurement method is utilized to determine velocity distributions on the intake-valve/cylinder boundary for different induction system designs. The velocity information is being used to calculate the angular momentum flux and to define local discharge coefficients around the valve periphery. The contribution of local flow direction (effective area) and local flow speed (velocity losses) to the global discharge coefficients is examined. The dependence of the discharge coefficient on the flow direction and mean velocity magnitude provides useful diagnostic data to relate intake port geometry and flow performance. The measurement technique is also described in detail. The directional response of a single hot-wire anemometer is utilized along with sequential sampling of the signal as the probe shaft is rotated through 360 deg. Within the range of velocity and flow direction required, the velocity magnitude and direction can be determined to within 2 percent and 2 deg, respectively.

Measurements with a pulsed-wire and a hot-wire anemometer in the highly turbulent wake of a normal flat plate

1976 ◽  
Vol 77 (3) ◽  
pp. 473-497 ◽  
Author(s):  
L. J. S. Bradbury
Keyword(s):  
Turbulent Flow ◽  
Flat Plate ◽  
Flow Direction ◽  
Operating Conditions ◽  
Turbulent Intensity ◽  
Hot Wire ◽  
Mean Flow ◽  
Mean Velocity ◽  
The Mean ◽  
Better Than

This paper describes an investigation into the response of both the pulsed-wire anemometer and the hot-wire anemometer in a highly turbulent flow. The first part of the paper is concerned with a theoretical study of some aspects of the response of these instruments in a highly turbulent flow. It is shown that, under normal operating conditions, the pulsed-wire anemometer should give mean velocity and longitudinal turbulent intensity estimates to an accuracy of better than 10% without any restriction on turbulence level. However, to attain this accuracy in measurements of turbulent intensities normal to the mean flow direction, there is a lower limit on the turbulent intensity of about 50%. An analysis is then carried out of the behaviour of the hot-wire anemometer in a highly turbulent flow. It is found that the large errors that are known to develop are very sensitive to the precise structure of the turbulence, so that even qualitative use of hot-wire data in such flows is not feasible. Some brief comments on the possibility of improving the accuracy of the hot-wire anemometer are then given.The second half of the paper describes some comparative measurements in the highly turbulent flow immediately downstream of a normal flat plate. It is shown that, although it is not possible to interpret the hot-wire results on their own, it is possible to calculate the hot-wire response with a surprising degree of accuracy using the results from the pulsed-wire anemometer. This provides a rather indirect but none the less welcome check on the accuracy of the pulsed-wire results, which, in this very highly turbulent flow, have a certain interest in their own right.

Some Corrections to the Linearized Response of a Constant-Temperature Hot-Wire Anemometer Operated in a Low-Speed Flow

1962 ◽  
Vol 29 (3) ◽  
pp. 554-558 ◽  
Author(s):  
W. G. Rose
Keyword(s):  
Shear Stress ◽  
Constant Temperature ◽  
Flow Direction ◽  
Turbulent Intensity ◽  
Order Effects ◽  
Fluid Temperature ◽  
Hot Wire ◽  
Mean Velocity ◽  
Low Speed ◽  
Speed Flow

An equation is obtained for the instantaneous response of a constant-temperature hot-wire anemometer having a linearized output. The result includes the second-order effects of variations in fluid temperature and in flow direction. Corrected equations for outputs in terms of mean velocity, turbulent-intensity components, and shear stress are derived from the instantaneous response.

The Measurements of Mean Flow Angles Between an Automotive Fan and Stator

2002 ◽  
Author(s):  
Gregory A. Kopp ◽  
Robert J. Martinuzzi
Keyword(s):  
Flow Direction ◽  
Leading Edge ◽  
Laser Doppler Velocimeter ◽  
Hot Wire ◽  
Mean Flow ◽  
Mean Velocity ◽  
Flow Angle ◽  
Automotive Engine ◽  
Engine Cooling ◽  
The Mean

Measurements of the mean velocity vector were conducted to determine the exit angle from an automotive engine cooling fan module. The measurements were made at 15 locations along a radius between the hub and the band. The radius investigated was located in a plane roughly half-way between the blade trailing edge and stator leading edge. A two-component laser Doppler velocimeter and a four-wire hot-wire probe were used to measure the flow fields. It was found that the results obtained from hot-wire anemometry will have significant bias errors when used to measure the velocity vectors between the fan and the stator unless phase-averaged data are obtained with the probe re-oriented by phase. The differences between the techniques occur because the distribution of instantaneous swirl angles is bi-modal. Further, the mean flow angle is close to a local minimum in the probability density function of the swirl angle. This will act to increase errors in measurement devices whose accuracy depends on flow direction (the quantity being measured) such as five-hole probes which are used in industry.

The Use of a Hot-Wire Anemometer in Turbulent Flow

1967 ◽  
Vol 71 (679) ◽  
pp. 511-513 ◽  
Author(s):  
B. J. Hoole ◽  
J. R. Calvert
Keyword(s):  
Turbulent Flow ◽  
Flow Direction ◽  
Unsteady Flows ◽  
Wire Length ◽  
Hot Wire ◽  
Velocity Measurements ◽  
Local Flow ◽  
The Wire ◽  
Stream Direction

The hot-wire anemometer is one of the few instruments which can be used to make velocity measurements in turbulent and unsteady flows. However, the probe supporting the wire inevitably interferes with the local flow and it has been found that the effect of this interference on the reading of the anemometer varies considerably as the orientation of the probe to the flow direction is changed (the wire itself being maintained in the same direction). This leads to errors in any measurements taken where the instantaneous local flow direction differs significantly at any time from the direction for which the anemometer was calibrated. Such errors are quite separate from, and in addition to, errors due to finite wire length, incidence of the wire to the local stream direction, etc.

scholarly journals New velocity map and mass-balance estimate of Mertz Glacier, East Antarctica, derived from Landsat sequential imagery

2003 ◽  
Vol 49 (167) ◽  
pp. 503-511 ◽  
Author(s):  
Etienne Berthier ◽  
Bruce Raup ◽  
Ted Scambos
Keyword(s):  
Velocity Field ◽  
Drainage Basin ◽  
Flow Speed ◽  
East Antarctica ◽  
Landsat Images ◽  
Mean Velocity ◽  
Speed Increase ◽  
Glacier System ◽  
Show Evidence ◽  
Basal Melting

AbstractAutomatic feature tracking on two Landsat images (acquired inJanuary 2000 and December 2001) generates a complete and accurate velocity field of Mertz Glacier, East Antarctica. This velocity field shows two main tributaries to the ice stream. Between the tributaries, a likely obstruction feature in the bedrock results in a slow-down of the flow. A third Landsat image, acquired in 1989 and combined with the 2000 image, permits the determination of the glacier mean velocity during the 1990s. Although some parts of the Mertz Glacier system show evidence of slight speed increase, we conclude that the Mertz flow speed is constant within our uncertainty (35 m a−1). Using this complete velocity field, new estimates of the ice discharge flux, 17.8 km3 a−1 (16.4 Gt a−1), and of the basal melting of the tongue, 11 m a−1 of ice, are given. Our results lead to an apparent imbalance of the drainage basin (ice discharge 3.5 km3 a−1 lower than the accumulation). Considering previous studies in the Mertz Glacier area, we then discuss the uncertainty of this imbalance and the problems with accumulation mapping for this region.

Stability of slender inverted flags and rods in uniform steady flow

2016 ◽  
Vol 809 ◽  
pp. 873-894 ◽  
Author(s):  
John E. Sader ◽  
Cecilia Huertas-Cerdeira ◽  
Morteza Gharib
Keyword(s):  
Multiple Equilibria ◽  
Complex Dynamics ◽  
Flow Direction ◽  
Flow Speed ◽  
Uniform Flow ◽  
Biological Phenomena ◽  
Cantilever Length ◽  
The Stability ◽  
Elastic Sheets ◽  
Clamped Edge

Cantilevered elastic sheets and rods immersed in a steady uniform flow are known to undergo instabilities that give rise to complex dynamics, including limit cycle behaviour and chaotic motion. Recent work has examined their stability in an inverted configuration where the flow impinges on the free end of the cantilever with its clamped edge downstream: this is commonly referred to as an ‘inverted flag’. Theory has thus far accurately captured the stability of wide inverted flags only, i.e. where the dimension of the clamped edge exceeds the cantilever length; the latter is aligned in the flow direction. Here, we theoretically examine the stability of slender inverted flags and rods under steady uniform flow. In contrast to wide inverted flags, we show that slender inverted flags are never globally unstable. Instead, they exhibit bifurcation from a state that is globally stable to multiple equilibria of varying stability, as flow speed increases. This theory is compared with new and existing measurements on slender inverted flags and rods, where excellent agreement is observed. The findings of this study have significant implications to investigations of biological phenomena such as the motion of leaves and hairs, which can naturally exhibit a slender geometry with an inverted configuration.

Theoretical Parameter Study of Aerodynamic Vectoring Particle Sorting

2007 ◽  
Vol 129 (7) ◽  
pp. 902-907 ◽  
Author(s):  
Dane N. Jackson ◽  
Barton L. Smith
Keyword(s):  
Density Ratio ◽  
Large Data ◽  
Flow Speed ◽  
Spherical Particles ◽  
Parameter Study ◽  
Particle Sizes ◽  
Case Scenario ◽  
Velocity Magnitude ◽  
Particle Sorting ◽  
Sorting Technique

A new particle sorting technique called aerodynamic vectoring particle sorting (AVPS) has recently been shown to be effective at sorting particles without particles contacting surfaces. The technique relies on turning a free jet sharply without extended control surfaces. The flow turning results in a balance of particle inertia and several forces (pressure, drag, added mass, and body forces) that depend on particle size and density. The present paper describes a theoretical study of particle sorting in a turning flow. The purpose of this study is to extend AVPS to parameter spaces other than those that are currently under investigation. Spherical particles are introduced into a turning flow in which the velocity magnitude increases like r. The trajectory of each particle is calculated using the particle equation of motion with drag laws that are appropriate for various Knudsen number regimes. Large data sets can be collected rapidly for various particle sizes, densities, turning radii, flow speeds, and fluid properties. Ranges of particle sizes that can be sorted are determined by finding an upper bound (where particles move in a straight line) and a lower bound (where particles follow flow streamlines). It is found that the size range of particles that can be sorted is larger for smaller turning radii, and that the range moves toward smaller particles as the flow speed and the particle-to-fluid density ratio are increased. Since this flow is laminar and 2-D, and particle loading effects are ignored, the results represent a “best case” scenario.

scholarly journals Temperature-compensated fiber-optic gas flow speed sensor based on the ‘Hot-wire’ principle

Optik ◽  
2020 ◽  
pp. 166118
Author(s):  
Zhen Li ◽  
Jiqiang Wang ◽  
Xiaoxing Zhong ◽  
Tongyu Liu ◽  
Yanong Ning ◽  
...  
Keyword(s):  
Gas Flow ◽  
Fiber Optic ◽  
Flow Speed ◽  
Hot Wire ◽  
Speed Sensor

Fluid Control with Hydrophobic Pillars in Paper-Based Microfluidics

2021 ◽  
Author(s):  
Jingji Liu ◽  
Boyang Zhang ◽  
Yajun Zhang ◽  
Yiqiang Fan
Keyword(s):  
Propagation Velocity ◽  
Control Method ◽  
Flow Direction ◽  
Flow Speed ◽  
Hydrophobic Barrier ◽  
Pillar Arrays ◽  
Paper Based Microfluidics ◽  
Fluid Control ◽  
Medical Analysis ◽  
Fluid Manipulation

Abstract Paper-based microfluidics has been widely used in chemical and medical analysis applications. In the conventional paper-based microfluidic approach, fluid is propagating inside the porous structure, and the flow direction of the fluid propagation is usually controlled with the pre-defined hydrophobic barrier (e.g. wax). However, the fluid propagation velocity inside the paper-based microfluidic devices largely depends on the material properties of paper and fluid, the relative control method is rarely reported. In this study, a fluid propagation velocity control method is proposed for paper-based microfluidics: hydrophobic pillar arrays with different configurations were deposited in the microchannels in paper-based microfluidics for flow speed control, result indicates the deposited hydrophobic pillar arrays can effectively slow down the fluid propagation at different levels and can be used to passively control the fluid propagation inside microchannels for paper-based microfluidics. For the demonstration of the proposed fluid control methods, a paper-based microfluidic device for nitrite test in water was also fabricated. The proposed fluid control method for paper-based microfluidics may have significant importance for applications that involve sequenced reactions and more actuate fluid manipulation.

Hot Wire Measurements at the Exit of a Centrifugal Compressor Impeller

1979 ◽  
Vol 193 (1) ◽  
pp. 341-347
Author(s):  
A. Goulas ◽  
R. C. Baker
Keyword(s):  
Centrifugal Compressor ◽  
Magnetic Tape ◽  
Reynolds Stresses ◽  
Hot Wire ◽  
Mean Velocity ◽  
Isentropic Flow ◽  
Compressor Impeller ◽  
The Mean

Hot wire measurements at the exit of a small centrifugal compressor impeller are reported. Three different hot wire readings were obtained and stored on a magnetic tape for each point by gating the analogue hot wire signal with a pulse which indicated circumferential position. The combination of the three readings yielded the mean velocity and some Reynolds stresses at each point. The measurements show a ‘jet-wake’ profile towards the shroud and ‘isentropic’ flow near the hub.

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