Quasi Two-Dimensional Flow-Adaptive Algorithm for Pneumatic Probe Measurements

The subject of this paper is a flow-adaptive measurement grid algorithm developed for one-dimensional (1D) and two-dimensional (2D) flow field surveys with pneumatic probes in turbomachinery flows. The algorithm automatically determines the distribution and the amount of measurement points needed for an approximation of the pressure distribution within a predefined accuracy. The algorithm is based on transient traverses, conducted back and forth in the circumferential direction. A correction of the dynamic response is applied by deconvolving the transient measurement data using the information embedded in both transient measurements. In consequence, the performance of the algorithm is largely independent of the transient traversing speed and the geometry of the pressure measuring system. Insertion and removal strategies are incorporated in order to reduce measurement points and increase robustness toward differing flow field conditions. The performance of the algorithm is demonstrated for 2D flow field surveys with a pneumatic five-hole probe in an annular cascade wind tunnel. The measurement grid points are automatically adjusted so that a consistent resolution of the flow features is achieved within the measurement domain. Furthermore, the application of the algorithm shows a significant reduction in the number of measurement points. Compared to the measurement duration based on uniform grids, the duration is reduced by at least 7%, while maintaining a high accuracy of the measurement. The purpose of this paper is to demonstrate the performance of measurement grids adapted to local flow field conditions. Consequently, valuable measurement time can be saved without a loss in quality of the data obtained.

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Quasi 2D Flow-Adaptive Algorithm for Pneumatic Probe Measurements

Volume 6: Ceramics; Controls, Diagnostics and Instrumentation; Education; Manufacturing Materials and Metallurgy ◽

10.1115/gt2016-56624 ◽

2016 ◽

Author(s):

Christian Bartsch ◽

Magnus Hölle ◽

Peter Jeschke ◽

Timo Metzler

Keyword(s):

Flow Field ◽

Dynamic Response ◽

Pressure Distribution ◽

Measurement Data ◽

Field Conditions ◽

Measuring System ◽

Local Flow ◽

Field Surveys ◽

2D Flow ◽

Adaptive Measurement

The subject of this paper is a flow-adaptive measurement grid algorithm developed for 1D and 2D flow field surveys with pneumatic probes in turbomachinery flows. The algorithm automatically determines the distribution and the amount of measurement points needed for an approximation of the pressure distribution within a predefined accuracy. The algorithm is based on transient traverses, conducted back and forth in the circumferential direction. The dynamic response of the pressure-measuring system is disregarded during the traverses, which serve to detect changes in the pressure field. In contrast to previous investigations by the authors, a correction of the dynamic response is applied by deconvolving the transient measurement data using the information embedded in both transient measurements. In consequence, the performance of the algorithm is — to a large extent — independent of the transient traversing speed and the geometry of the pressure-measuring system. Insertion and removal strategies are incorporated in order to reduce measurement points and increase robustness towards differing flow field conditions. By approximation of the pressure distribution, the flow-adaptive measurement data is suited for the application of post-processing corrections without any constraints. The performance of the algorithm is demonstrated for 2D flow field surveys with a pneumatic 5-hole probe in an annular cascade wind tunnel. Compared to conventional techniques for data sampling, e.g., uniform measurement grids, the measurement grid points are automatically adjusted so that a consistent resolution of the flow features is achieved within the measurement domain. Furthermore, the application of the algorithm shows a significant reduction in the number of measurement points. Compared to the measurement duration based on uniform grids, the duration is reduced by at least 7%, while maintaining a high accuracy of the measurement. The purpose of this paper is to demonstrate the performance of measurement grids adapted to local flow field conditions. Consequently, valuable measurement time can be saved without a loss in quality of the data obtained.

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Incipient motion of solid particles in a two-dimensional flow field

10.31274/rtd-180813-17389 ◽

1960 ◽

Author(s):

Connayil Mani Jacob

Keyword(s):

Flow Field ◽

Solid Particles ◽

Two Dimensional ◽

Incipient Motion ◽

Dimensional Flow ◽

Two Dimensional Flow

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Two-dimensional flow field distribution characteristics of flocking drainage pipes in tunnel

Open Physics ◽

10.1515/phys-2020-0013 ◽

2020 ◽

Vol 18 (1) ◽

pp. 139-148

Author(s):

Shiyang Liu ◽

Xuefu Zhang ◽

Feng Gao ◽

Liangwen Wei ◽

Qiang Liu ◽

...

Keyword(s):

Flow Field ◽

Field Distribution ◽

Rapid Development ◽

Maximum Velocity ◽

Distribution Characteristics ◽

Two Dimensional ◽

Dimensional Flow ◽

Laboratory Test Results ◽

Transverse Distance ◽

Two Dimensional Flow

AbstractWith the rapid development of traffic infrastructure in China, the problem of crystal plugging of tunnel drainage pipes becomes increasingly salient. In order to build a mechanism that is resilient to the crystal plugging of flocking drainage pipes, the present study used the numerical simulation to analyze the two-dimensional flow field distribution characteristics of flocking drainage pipes under different flocking spacings. Then, the results were compared with the laboratory test results. According to the results, the maximum velocity distribution in the flow field of flocking drainage pipes is closely related to the transverse distance h of the fluff, while the longitudinal distance h of the fluff causes little effect; when the transverse distance h of the fluff is less than 6.25D (D refers to the diameter of the fluff), the velocity between the adjacent transverse fluffs will be increased by more than 10%. Moreover, the velocity of the upstream and downstream fluffs will be decreased by 90% compared with that of the inlet; the crystal distribution can be more obvious in the place with larger velocity while it is less at the lower flow rate. The results can provide theoretical support for building a mechanism to deal with and remove the crystallization of flocking drainage pipes.

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Flow Visualization by Means of Contactless Inductive Flow Tomography in the Presence of a Magnetic Brake

Journal for Manufacturing Science and Production ◽

10.1515/jmsp-2014-0037 ◽

2015 ◽

Vol 15 (1) ◽

pp. 41-48 ◽

Cited By ~ 1

Author(s):

Matthias Ratajczak ◽

Thomas Wondrak ◽

Klaus Timmel ◽

Frank Stefani ◽

Sven Eckert

Keyword(s):

Magnetic Field ◽

External Magnetic Field ◽

Magnetic Fields ◽

Flow Field ◽

Continuous Casting ◽

Flow Structure ◽

Cross Section ◽

Two Dimensional ◽

Slab Casting ◽

Two Dimensional Flow

AbstractIn continuous casting DC magnetic fields perpendicular to the wide faces of the mold are used to control the flow in the mold. Especially in this case, even a rough knowledge of the flow structure in the mold would be highly desirable. The contactless inductive flow tomography (CIFT) allows to reconstruct the dominating two-dimensional flow structure in a slab casting mold by applying one external magnetic field and by measuring the flow-induced magnetic fields outside the mold. For a physical model of a mold with a cross section of 140 mm×35 mm we present preliminary measurements of the flow field in the mold in the presence of a magnetic brake. In addition, we show first reconstructions of the flow field in a mold with the cross section of 400 mm×100 mm demonstrating the upward scalability of CIFT.

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Towed Underwater SPIV Measurement of Flow Fields Around a Surface-Piercing Cylinder With Free Surface Effects

Volume 1A: Symposia, Part 2 ◽

10.1115/ajkfluids2015-20165 ◽

2015 ◽

Author(s):

Jeonghwa Seo ◽

Bumwoo Han ◽

Shin Hyung Rhee

Keyword(s):

Boundary Layer ◽

Free Surface ◽

Surface Wave ◽

Flow Field ◽

Cross Section ◽

Surface Effects ◽

Flow Fields ◽

Two Dimensional ◽

Two Dimensional Flow ◽

Wave Induced

Effects of free surface on development of turbulent boundary layer and wake fields were investigated. By measuring flow field around a surface piercing cylinder in various advance speed conditions in a towing tank, free surface effects were identified. A towed underwater Stereoscopic Particle Image Velocimetry (SPIV) system was used to measure the flow field under free surface. The cross section of the test model was water plane shape of the Wigley hull, of which longitudinal length and width were 1.0 m and 100 mm, respectively. With sharp bow shape and slender cross section, flow separation was not expected in two-dimensional flow. Flow fields near the free-surface and in deep location that two-dimensional flow field was expected were measured and compared to identify free-surface effects. Some planes perpendicular to longitudinal direction near the model surface and behind the model were selected to track development of turbulent boundary layer. Froude numbers of the test conditions were from 0.126 to 0.40 and corresponding Reynolds numbers were from 395,000 to 1,250,000. In the lowest Froude number condition, free-surface wave was hardly observed and only free surface effects without surface wave could be identified while violent free-surface behavior due to wave-induced separation dominated the flow fields in the highest Froude number condition. From the instantaneous velocity fields, Time-mean velocity, turbulence kinetic energy, and flow structure derived by proper orthogonal decomposition (POD) were analyzed. As the free-surface effect, development of retarded wake, free-surface waves, and wave-induced separation were mainly observed.

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Extension of the Prandtl–Batchelor theorem to three-dimensional flows slowly varying in one direction

Journal of Fluid Mechanics ◽

10.1017/s0022112010001485 ◽

2010 ◽

Vol 654 ◽

pp. 351-361 ◽

Cited By ~ 1

Author(s):

M. SANDOVAL ◽

S. CHERNYSHENKO

Keyword(s):

Flow Field ◽

Small Parameter ◽

Order Approximation ◽

Three Dimensional ◽

Inviscid Limit ◽

Two Dimensional ◽

Leading Order ◽

Dimensional Flow ◽

Two Dimensional Flow

According to the Prandtl–Batchelor theorem for a steady two-dimensional flow with closed streamlines in the inviscid limit the vorticity becomes constant in the region of closed streamlines. This is not true for three-dimensional flows. However, if the variation of the flow field along one direction is slow then it is possible to expand the solution in terms of a small parameter characterizing the rate of variation of the flow field in that direction. Then in the leading-order approximation the projections of the streamlines onto planes perpendicular to that direction can be closed. Under these circumstances the extension of the Prandtl–Batchelor theorem is obtained. The resulting equations turned out to be a three-dimensional analogue of the equations of the quasi-cylindrical approximation.

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