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Journal articles on the topic 'Wall blowing'

Author: Grafiati

Published: 4 June 2021

Last updated: 17 February 2022

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1

Abu-Nada, E., A. Al-Sarkhi, B. Akash, and I. Al-Hinti. "Heat Transfer and Fluid Flow Characteristics of Separated Flows Encountered in a Backward-Facing Step Under the Effect of Suction and Blowing." Journal of Heat Transfer 129, no. 11 (February 1, 2007): 1517–28. http://dx.doi.org/10.1115/1.2759973.

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Abstract Numerical investigation of heat transfer and fluid flow over a backward-facing step (BFS), under the effect of suction and blowing, is presented. Here, suction/blowing is implemented on the bottom wall (adjacent to the step). The finite volume technique is used. The distribution of the modified coefficient of friction and Nusselt number at the top and bottom walls of the BFS are obtained. On the bottom wall, and inside the primary recirculation bubble, suction increases the modified coefficient of friction and blowing reduces it. However, after the point of reattachment, mass augmentation causes an increase in the modified coefficient of friction and mass reduction causes a decrease in modified coefficient of friction. On the top wall, suction decreases the modified coefficient of friction and blowing increases it. Local Nusselt number on the bottom wall is increased by suction and is decreased by blowing, and the contrary occurs on the top wall. The maximum local Nusselt number on the bottom wall coincides with the point of reattachment. High values of average Nusselt number on the bottom wall are identified at high Reynolds numbers and high suction bleed rates. However, the low values correspond to high blowing rates. The reattachment length and the length of the top secondary recirculation bubble are computed under the effect of suction and blowing. The reattachment length is increased by increasing blowing bleed rate and is decreased by increasing suction bleed rate. The spots of high Nusselt number, and low coefficient of friction, are identified by using contour maps.

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2

AMITAY, MICHAEL, and JACOB COHEN. "Instability of a two-dimensional plane wall jet subjected to blowing or suction." Journal of Fluid Mechanics 344 (August 10, 1997): 67–94. http://dx.doi.org/10.1017/s0022112097006071.

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The effects of wall blowing or suction on the stability characteristics of a laminar incompressible two-dimensional plane wall jet are investigated both experimentally and theoretically. A quantitative comparison between linear stability calculations and phase-locked experimental data, obtained when the wall jet is subjected to two-dimensional excitations, confirms the co-existence of the viscous and inviscid instability modes and the theoretically predicted effects of blowing and suction on the stability of the wall jet. According to these predicted effects, blowing stabilizes the inviscid mode while destabilizing the viscous one; suction has the opposite effect. Furthermore, blowing and suction tend to increase and decrease, respectively, the ratio between the outer and inner amplitude maxima of the streamwise velocity fluctuation. When wall blowing is applied, the instability domain is enlarged and includes higher-frequency waves. In addition, the region where both unstable modes co-exist simultaneously begins at a lower local Reynolds number. Opposite effects are caused when suction is applied. The quantitative comparison between the theory and experiment includes the cross-stream structure and the downstream growth of the streamwise velocity fluctuations. In order to accurately account for the effect of the mean flow divergence in the stability analysis, the second-order corrections to the mean flow solutions are obtained for all wall conditions. Spectral distributions, obtained when natural wall-jets are subjected to blowing and suction, support qualitatively the above results.

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3

TARDU, SEDAT F. "Active control of near-wall turbulence by local oscillating blowing." Journal of Fluid Mechanics 439 (July 23, 2001): 217–53. http://dx.doi.org/10.1017/s0022112001004542.

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The effect of time-periodical blowing through a spanwise slot on the near-wall turbulence characteristics is investigated. The blowing velocity changes in a cyclic manner from 0 to 5 wall units. The frequency of the oscillations is nearly equal to the median frequency of the near-wall turbulence. The measurements of the wall shear stress and the streamwise velocity are reported and discussed. The flow field near the blowing slot is partly relaminarized during the acceleration phase of the injection velocity which extends 40 wall units downstream. The imposed unsteadiness is confined to the buffer layer, and the time-mean structural parameters under unsteady blowing are found to be close to those of isotropic turbulence in this region. The relaminarized phase is unstable and gives way to a coherent spanwise structure that increases the shear from 80 to 300 wall units downstream of the slot in a predictable way. This phenomenon is strongly imposed-frequency dependent.

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4

Chung, Yongmann M., Hyung Jin Sung, and P. A. Krogstad. "Modulation of Near-Wall Turbulence Structure with Wall Blowing and Suction." AIAA Journal 40, no. 8 (August 2002): 1529–35. http://dx.doi.org/10.2514/2.1849.

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5

Chung, Y. M., H. J. Sung, and P. A. Krogstad. "Modulation of near-wall turbulence structure with wall blowing and suction." AIAA Journal 40 (January 2002): 1529–35. http://dx.doi.org/10.2514/3.15227.

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6

Doche, Olivier, and Sedat Tardu. "Mechanism of wall transfer under steady localized blowing." International Journal of Heat and Mass Transfer 55, no. 5-6 (February 2012): 1574–81. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2011.11.013.

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7

Marchisio, C. "Polystyrene shells from pellets containing a chemical blowing agent." Laser and Particle Beams 10, no. 3 (September 1992): 485–93. http://dx.doi.org/10.1017/s026303460000673x.

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A new method for fabricating polystyrene ICF targets has been investigated. A solid solution of polystyrene (PS) containing a chemical blowing agent (CBA) is divided into small granules. These granules are blown into spherical shells in a vertical furnace. By varying the type and amount of CBA as well as furnace parameters, we have been able to produce PS shells 200–600 μm in diameter with wall thicknesses from 4–20 μm.

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8

Vlassov, D., J. V. C. Vargas, J. C. Ordonez, and L. S. Martins. "TURBULENT STRESS DISTRIBUTION IN THE TURBULENT BOUNDARY LAYER ON A PERMEABLE POROUS PLATE." Revista de Engenharia Térmica 5, no. 1 (July 31, 2006): 90. http://dx.doi.org/10.5380/reterm.v5i1.61678.

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In this paper the results of experimental tests on turbulent boundary layer on a plate with air blowing through permeable porous wall are presented. Tests were performed in an aerodynamic tunnel varying the blowing rate within the range of 0 to 2.5% of the air flow velocity in the tunnel, using thermoanemometers of constant temperature. It has been determined that the blowing increases the boundary layer thickness and strongly transforms the boundary layer inner part and turbulent nucleus, while the outer part remains not deformed. An increase in blowing causes an abrupt viscous stress decrease, also decreasing skin friction. Thick boundary layers (up to 120 mm) allowed a profound analysis of Reynolds' turbulent stresses. It has been found a general distribution of turbulent stress in the turbulent layer which is independent of blowing velocity. It has been established for the turbulent characteristics that the determining coordinate is the relative horizontal velocity, not the distance from the wall. With a turbulent stress database obtained from turbulent stresses direct measurements, it has been proposed a flow model for boundary layer on a permeable porous plate. It has also been demonstrated that in high blowing conditions the horizontal velocity profile in the boundary layer becomes equal to the velocity profile in a plane jet.

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9

Goldstein, R. J., and L. D. Stone. "Row-of-Holes Film Cooling of Curved Walls at Low Injection Angles." Journal of Turbomachinery 119, no. 3 (July 1, 1997): 574–79. http://dx.doi.org/10.1115/1.2841160.

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Film cooling effectiveness data are presented against a backdrop of ammonia-diazo flow visualizations for row-of-holes injection along a convex wall and a concave wall at angles of 15, 25, and 45 deg to the mainstream and at density ratios of approximately one and two. Injection angle effects vary with the rate of injection: At low blowing rates the injection angle is unimportant, at moderate blowing rates the shallower angles provide better effectiveness, and at high blowing rates a steeper injection angle sometimes provides better effectiveness. The condition of the local boundary layer, the severity of jet lift-off, and the strength of vortex interactions among the bound vortices of neighboring jets are key considerations in interpreting the data.

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10

Miró Miró, Fernando, Pieter Dehairs, Fabio Pinna, Maria Gkolia, Davide Masutti, Tamas Regert, and Olivier Chazot. "Effect of Wall Blowing on Hypersonic Boundary-Layer Transition." AIAA Journal 57, no. 4 (April 2019): 1567–78. http://dx.doi.org/10.2514/1.j057604.

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11

Hwang, Kun, and Han Joon Kim. "Medial Orbital Wall Fracture Caused by Forceful Nose Blowing." Journal of Craniofacial Surgery 25, no. 2 (March 2014): 720–21. http://dx.doi.org/10.1097/scs.0000000000000532.

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12

Tardu, Sedat. "Near wall turbulence control by local time periodical blowing." Experimental Thermal and Fluid Science 16, no. 1-2 (January 1998): 41–53. http://dx.doi.org/10.1016/s0894-1777(97)10011-5.

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13

Na, Yang, and Chang-Jin Lee. "Oscillation Characteristics of Turbulent Channel Flow with Wall Blowing." Journal of the Korean Society for Aeronautical & Space Sciences 37, no. 1 (January 1, 2009): 62–68. http://dx.doi.org/10.5139/jksas.2009.37.1.062.

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14

Gao, Peng, and Xi-Yun Lu. "Instability of channel flow with oscillatory wall suction/blowing." Physics of Fluids 18, no. 3 (March 2006): 034102. http://dx.doi.org/10.1063/1.2186673.

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15

Kim, Kwang Ung, Tae Suk Park, and Byoung Chul Kim. "Rigid Foam Extrusion of Polyvinylchloride – Effects of Blowing Agent and Plasticizer." Journal of Polymer Engineering 7, no. 1 (January 1, 1986): 1–12. http://dx.doi.org/10.1515/polyeng-1986-0102.

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Abstract The effects of blowing agent and plasticizer on foaming characteristics of polyvinylchloride (PVC) were investigated, using a short cylindrical die. Of two blowing agents tested, azodicarbonamide (ADCA) exhibited a wider leverage of volumetric flow rate for processability while sodium bicarbonate (SBC) showed a wider temperature leverage. The mixed use of two blowing agents gave a better control for extrudate density, product color and processability. Of three nucleating agents, two acidic ones, citric acid and boric acid, enhanced uniformity of cells and efficiency of the blowing agents slightly. It was observed that dioctyl phthalate (DOP), used as plasticizer, tended to migrate toward the surface of the die wall, giving rise to smooth surface layer of the extruded profile foam. A possibility exists to produce profile foams having smooth skin, by controlling the type of blowing agent and processing conditions.

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16

Xu, Wei Qing, and Mao Lin Cai. "Research on Optimization of Air Blowing System." Applied Mechanics and Materials 34-35 (October 2010): 600–604. http://dx.doi.org/10.4028/www.scientific.net/amm.34-35.600.

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Many studies have been made for years on dimensions of pneumatic nozzle. To output same blowing force, the supply pressure could be reduced by decreasing the ratio of length to diameter of nozzle. The friction between high speed air and pipe wall would be reduced if the nozzle is designed to be converging shape comparing with straight shape. But the volume flow and pressure, discussed in these studies, do not describe energy loss of the blowing system directly. Pneumatic power is an innovative principle to estimate pneumatic system’s energy consumption directly. Based on the principle, the supply pressure of air blowing system is a critical parameter concerning energy consumption and blowing force. In the experiment, the air blowing system is supplied by a compressor and an air blower respectively. The pressure of air from the compressor is times higher than air blower. A comparison is preformed to the two systems about energy consumption and blowing force. From the result, the air blowing system with air blower consumes less energy than with compressor. This study provides theoretical basis for designing energy-saving air blowing system.

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17

Diao, Xi Lian. "A Ceramic Filter Counter Blowing Regeneration Control System." Applied Mechanics and Materials 457-458 (October 2013): 1245–48. http://dx.doi.org/10.4028/www.scientific.net/amm.457-458.1245.

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This paper developed a high efficiency, simple to use and reliable, strong practicability of model 6120 diesel particulate filter regeneration control pulse inverse blow system. The pulse counter blowing regeneration test, and post-processing of particles back down to do the further research. The experimental results show that this device can wall honeycomb ceramic filter for filtering and counter blowing regeneration test and research.

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18

Schwarz, S. G., and R. J. Goldstein. "The Two-Dimensional Behavior of Film Cooling Jets on Concave Surfaces." Journal of Turbomachinery 111, no. 2 (April 1, 1989): 124–30. http://dx.doi.org/10.1115/1.3262246.

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Local impermeable wall effectiveness is measured along a concave surface downstream of a row of film cooling jets. Three different injection hole diameters, two density ratios (0.95 and 2.0), and a wide range of blowing rates (0.3 to 2.7) are considered. Except close to injection, where normal momentum is strong, an increase in blowing rate results in improved film cooling performance. This is attributed to an increase in thermal mass (capacity) of coolant, tangential momentum of the jet, and blockage. Far downstream of injection, the normal and tangential momentum weaken, but blockage and large thermal mass at high injection rates still keep effectiveness high. Lateral mixing of the jets caused by the unstable concave mainflow results in film-cooling performance, which correlates well with the same parameter, which is influential in slot injection on a flat surface. Deviation from this two-dimensional behavior is found only at very low blowing rates and weak wall curvature.

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19

Liu, Can, and Xi Chen. "Probability Density Functions of Vorticities in Turbulent Channels with Effects of Blowing and Suction." International Journal of Nonlinear Sciences and Numerical Simulation 17, no. 2 (April 1, 2016): 127–35. http://dx.doi.org/10.1515/ijnsns-2015-0163.

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AbstractThis paper presents direct numerical simulation (DNS) result of the Navier–Stokes equations for turbulent channel flows with blowing and suction effects. The friction Reynolds number is ${\rm{R}}{{\rm{e}}_\tau} = 394$ and a range of blowing and suction conditions is covered with different perturbation strengths, i. e. $A = 0.05, $ 0.1, 0.2. While the mean velocity profile has been severely altered, the probability density function (PDF) for (spanwise) vorticity – depending on wall distance $({y^ +})$ and blowing/suction strength (A) – satisfies the generalized hyperbolic distribution (GHD) of Birnir [The Kolmogorov-Obukhov statistical theory of turbulence, J. Nonlinear Sci. (2013a), doi: 10.1007/s00332-012-9164–z; The Kolmogorov-Obukhov theory of turbulence, Springer, New York, 2013b] in the bulk of the flow. The latter leads to accurate descriptions of all PDFs (at ${y^ +} = 40, $ 200, 390 and $A = 0.05, $ 0.2, for instance) with only four parameters. The result indicates that GHD is a general tool to quantify PDF for turbulent flows under various wall surface conditions.

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20

Cherubini, S., J. C. Robinet, and P. De Palma. "Nonlinear control of unsteady finite-amplitude perturbations in the Blasius boundary-layer flow." Journal of Fluid Mechanics 737 (November 26, 2013): 440–65. http://dx.doi.org/10.1017/jfm.2013.576.

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AbstractThe present work provides an optimal control strategy, based on the nonlinear Navier–Stokes equations, aimed at hampering the rapid growth of unsteady finite-amplitude perturbations in a Blasius boundary-layer flow. A variational procedure is used to find the blowing and suction control law at the wall providing the maximum damping of the energy of a given perturbation at a given target time, with the final aim of leading the flow back to the laminar state. Two optimally growing finite-amplitude initial perturbations capable of leading very rapidly to transition have been used to initialize the flow. The nonlinear control procedure has been found able to drive such perturbations back to the laminar state, provided that the target time of the minimization and the region in which the blowing and suction is applied have been suitably chosen. On the other hand, an equivalent control procedure based on the linearized Navier–Stokes equations has been found much less effective, being not able to lead the flow to the laminar state when finite-amplitude disturbances are considered. Regions of strong sensitivity to blowing and suction have been also identified for the given initial perturbations: when the control is actuated in such regions, laminarization is also observed for a shorter extent of the actuation region. The nonlinear optimal blowing and suction law consists of alternating wall-normal velocity perturbations, which appear to modify the core flow structures by means of two distinct mechanisms: (i) a wall-normal velocity compensation at small times; (ii) a rotation-counterbalancing effect al larger times. Similar control laws have been observed for different target times, values of the cost parameter, and streamwise extents of the blowing and suction zone, meaning that these two mechanisms are robust features of the optimal control strategy, provided that the nonlinear effects are taken into account.

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21

McAuliffe, Brian R., and Steen A. Sjolander. "Active Flow Control Using Steady Blowing for a Low-Pressure Turbine Cascade." Journal of Turbomachinery 126, no. 4 (October 1, 2004): 560–69. http://dx.doi.org/10.1115/1.1791291.

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The paper presents mid-span measurements for a turbine cascade with active flow control. Steady blowing through an inclined plane wall jet has been used to control the separation characteristics of a high-lift low-pressure turbine airfoil at low Reynolds numbers. Measurements were made at design incidence for blowing ratios from approximately 0.25 to 2.0 (ratio of jet-to-local freestream velocity), for Reynolds numbers of 25,000 and 50,000 (based on axial chord and inlet velocity), and for freestream turbulence intensities of 0.4% and 4%. Detailed flow field measurements were made downstream of the cascade using a three-hole pressure probe, static pressure distributions were measured on the airfoil suction surface, and hot-wire measurements were made to characterize the interaction between the wall jet and boundary layer. The primary focus of the study is on the low-Reynolds number and low-freestream turbulence intensity cases, where the baseline airfoil stalls and high profile losses result. For low freestream turbulence (0.4%), the examined method of flow control was effective at preventing stall and reducing the profile losses. At a Reynolds number of 25,000, a blowing ratio greater than 1.0 was required to suppress stall. At a Reynolds number of 50,000, a closed separation bubble formed at a very low blowing ratio (0.25) resulting in a significant reduction in the profile loss. For high freestream turbulence intensity (4%), where the baseline airfoil has a closed separation bubble and low profile losses, blowing ratios below 1.0 resulted in a larger separation bubble and higher losses. The mechanism by which the wall jet affects the separation characteristics of the airfoil is examined through hot-wire traverse measurements in the vicinity of the slot.

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22

Wang, Xiaowen, Xiaolin Zhong, and Yanbao Ma. "Response of a Hypersonic Boundary Layer to Wall Blowing-Suction." AIAA Journal 49, no. 7 (July 2011): 1336–53. http://dx.doi.org/10.2514/1.j050173.

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23

Ball, W. H. "Tests of wall suction and blowing in highly offset diffusers." Journal of Aircraft 22, no. 3 (March 1985): 161–67. http://dx.doi.org/10.2514/3.45102.

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24

Labropulu, F., J. M. Dorrepaal, and O. P. Chandna. "Oblique flow impinging on a wall with suction or blowing." Acta Mechanica 115, no. 1-4 (March 1996): 15–25. http://dx.doi.org/10.1007/bf01187425.

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25

Viswanath, P. R., and K. T. Madhavan. "Control of trailing-edge separation by tangential blowing inside the bubble." Aeronautical Journal 108, no. 1086 (August 2004): 419–25. http://dx.doi.org/10.1017/s0001924000000233.

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Abstract Experiments have been performed investigating the effectiveness of steady tangential blowing, with the blowing slot located downstream of separation (but inside the separation bubble) to control a trailing-edge separated flow at low speeds. Trailing-edge separation was induced on a two-dimensional aerofoil-like body and the shear layer closure occurred in the near-wake. Measurements made consisted of model surface pressures and mean velocity, turbulent shear stress and kinetic energy profiles in the separated zone using a two-component LDV system. It is explicitly demonstrated that the novel concept of tangential blowing inside the bubble can be an effective means of control for trailing-edge separated flows as well. Blowing mass and momentum requirements for the suppression of wall and wake flow reversals have been estimated.

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26

Abdala, Antar M. M., Fifi N. M. Elwekeel, and Qun Zheng. "Film Cooling Adiabatic Effectiveness for Cylindrical Holes Embedded in Multi Trench Configuration." Advanced Materials Research 588-589 (November 2012): 1866–69. http://dx.doi.org/10.4028/www.scientific.net/amr.588-589.1866.

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In this study, computational simulations were made using ANSYS CFX to predict the improvements in film cooling performance with multi trench. Multi-trench configuration consists of two trenches together, one wider trench and the other is narrow trench that extruded from the wider one. Several blowing ratios in the range (0.5, 1, 2 and 3) were investigated. By using the multi trench configuration, the coolant jet impacted the trench wall two times allowing increasing the spreading of coolant laterally in the trench, reducing jet velocity and jet completely covered on the surface. The results indicate that this configuration increased adiabatic effectiveness as blowing ratio increased. The multi trench configuration increased adiabatic effectiveness up to 100% near the hole, 43% at X/D = 40 and 31% at downstream X/D = 137 for blowing ratio of 3 and no observed film blow-off at this blowing ratio. The adiabatic film effectiveness of multi trench configuration outperformed the narrow trench at different blowing ratios

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27

Tupý, David, and Václav Sláma. "Blowing Steam into the Boundary Layer on the Outer Wall of the Axial Exhaust Hood." MATEC Web of Conferences 328 (2020): 01002. http://dx.doi.org/10.1051/matecconf/202032801002.

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The paper is devoted to experimental verification of flow on the steam turbine axial exhaust hood model. The main goal of the submitted paper is to evaluate the influence of additional air blowing into the boundary layer in the axial exhaust hood on the change of the pressure recovery coefficient. The experimental model was supplemented with a blowing track and fitted with a centric orifice for mass flow measurement. Several variants were measured with various types of inner struts and supports inside the hood for two values of Mach number at the diffuser inlet.

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28

Yue, Jian Wei, and Xiu Ying Meng. "Experimental Research of Foaming Concrete Performance with Different Blowing Agent." Applied Mechanics and Materials 275-277 (January 2013): 2033–36. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.2033.

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Low-density foam concrete is inorganic silicate material replace to traditional organic materials for external wall insulation system. Based on the analysis of structure formation mechanism of foaming foam concrete prepared with chemical method, investigation by a large number of comparative tests and quantitative analysis, quantitative relationship of compressive strength, tensile strength, and blowing agent dosage quantitative of 3d, 7d and 28d foaming concrete are analyzed. The relationship between blowing agent and foam concrete strength and thermal conductivity variation is revealed by the research of doped foaming agent concrete strength, improved workability mechanism. And further, independent sealing pores, high mechanical strength of pore wall, pore structure approximate to sphere and pore diameter with similar and small size were all favorable factors for higher strength of foam concrete.

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29

Radespiel, R., M. Burnazzi, M. Casper, and P. Scholz. "Active flow control for high lift with steady blowing." Aeronautical Journal 120, no. 1223 (January 2016): 171–200. http://dx.doi.org/10.1017/aer.2015.7.

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ABSTRACTThe general picture of research in active flow control for aircraft applications has been continuously changing over the last 20 years. Researchers can now obtain design sensitivities by using numerical flow simulations, and new optical experimental methods can be used that measure flow field data non-intrusively in planes and volumes. These methodological advances enabled significant knowledge increase. The present paper reviews recent progress in active flow control by steady blowing. It appears that two strategies of blowing deserve particular attention. The first uses tangential blowing of thin wall jets to overcome the adverse pressure gradients from locally very large flow turning rates. This approach exploits the potentials of the Coanda effect. The second strategy employs oblique blowing of air jets designed to generate longitudinal vortices in the boundary layer. The longitudinal vortices provide convective redistribution of momentum in the boundary layer, and they also enhance turbulent momentum transport. The sensitivities of these two approaches as observed in fundamental flow investigations and in applications to high-lift aerofoils are described and suited efficiency parameters of blowing are analysed.

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30

Li, Guangchao, Yukai Chen, Zhihai Kou, Wei Zhang, and Guochen Zhang. "Mechanism of Film Cooling with One Inlet and Double Outlet Hole Injection at Various Turbulence Intensities." International Journal of Turbo & Jet-Engines 35, no. 1 (March 26, 2018): 1–9. http://dx.doi.org/10.1515/tjj-2016-0024.

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AbstractThe trunk-branch hole was designed as a novel film cooling concept, which aims for improving film cooling performance by producing anti-vortex. The trunk-branch hole is easily manufactured in comparison with the expanded hole since it consists of two cylindrical holes. The effect of turbulence on the film cooling effectiveness with a trunk-branch hole injection was investigated at the blowing ratios of 0.5, 1.0, 1.5 and 2.0 by numerical simulation. The turbulence intensities from 0.4 % to 20 % were considered. The realizable$k - \varepsilon $turbulence model and the enhanced wall function were used. The more effective anti-vortex occurs at the low blowing ratio of 0.5 %. The high turbulence intensity causes the effectiveness evenly distributed in the spanwise direction. The increase of turbulence intensity leads to a slight decrease of the spanwise averaged effectiveness at the low blowing ratio of 0.5, but a significant increase at the high blowing ratios of 1.5 and 2.0. The optimal blowing ratio of the averaged surface effectiveness is improved from 1.0 to 1.5 when the turbulence intensity increases from 0.4 % to 20 %.

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31

Wang, Yong Feng, Li Hua Gu, and Jian Wei Yue. "Experimental Research of Foaming Concrete Performance with Different Fly Ash." Applied Mechanics and Materials 275-277 (January 2013): 2037–40. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.2037.

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Low-density foam concrete is inorganic silicate material that can replace traditional organic materials for external wall insulation system. Based on the analysis of structure formation mechanism of foaming foam concrete prepared with chemical method, investigation by a large number of comparative tests and quantitative analysis, quantitative relationship of compressive strength, tensile strength, and blowing agent dosage quantitative of 3d, 7d and 28d foaming concrete are analyzed. The relationship between blowing agent and foam concrete strength and thermal conductivity variation is revealed by the research of doped fly ash concrete strength, improved workability mechanism. And further, independent sealing pores, high mechanical strength of pore wall, pore structure approximate to sphere and pore diameter with similar and small size were all favorable factors for higher strength of foam concrete.

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32

Llewelyn, Rees, Griffiths, and Jacobi. "A Novel Hybrid Foaming Method for Low-Pressure Microcellular Foam Production of Unfilled and Talc-Filled Copolymer Polypropylenes." Polymers 11, no. 11 (November 17, 2019): 1896. http://dx.doi.org/10.3390/polym11111896.

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Unfilled and talc-filled Copolymer Polypropylene (PP) samples were produced through low-pressure foam-injection molding (FIM). The foaming stage of the process has been facilitated through a chemical blowing agent (C6H7NaO7 and CaCO3 mixture), a physical blowing agent (supercritical N2) and a novel hybrid foaming (combination of said chemical and physical foaming agents). Three weight-saving levels were produced with the varying foaming methods and compared to conventional injection molding. The unfilled PP foams produced through chemical blowing agent exhibited the strongest mechanical characteristics due to larger skin wall thicknesses, while the weakest were that of the talc-filled PP through the hybrid foaming technique. However, the hybrid foaming produced superior microcellular foams for both PPs due to calcium carbonate (CaCO3) enhancing the nucleation phase.

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33

Avsarkisov, V., M. Oberlack, and S. Hoyas. "New scaling laws for turbulent Poiseuille flow with wall transpiration." Journal of Fluid Mechanics 746 (March 28, 2014): 99–122. http://dx.doi.org/10.1017/jfm.2014.98.

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AbstractA fully developed, turbulent Poiseuille flow with wall transpiration, i.e. uniform blowing and suction on the lower and upper walls correspondingly, is investigated by both direct numerical simulation (DNS) of the three-dimensional, incompressible Navier–Stokes equations and Lie symmetry analysis. The latter is used to find symmetry transformations and in turn to derive invariant solutions of the set of two- and multi-point correlation equations. We show that the transpiration velocity is a symmetry breaking which implies a logarithmic scaling law in the core of the channel. DNS validates this result of Lie symmetry analysis and hence aids establishing a new logarithmic law of deficit type. The region of validity of the new logarithmic law is very different from the usual near-wall log law and the slope constant in the core region differs from the von Kármán constant and is equal to 0.3. Further, extended forms of the linear viscous sublayer law and the near-wall log law are also derived, which, as a particular case, include these laws for the classical non-transpiring case. The viscous sublayer at the suction side has an asymptotic suction profile. The thickness of the sublayer increase at high Reynolds and transpiration numbers. For the near-wall log law we see an indication that it appears at the moderate transpiration rates ($\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}0.05<v_0/u_{\tau }<0.1$) and only at the blowing wall. Finally, from the DNS data we establish a relation between the friction velocity$u_{\tau }$and the transpiration$v_0$which turns out to be linear at moderate transpiration rates.

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34

Lu Chang-Gen and Shen Lu-Yu. "Numerical study on boundary-layer receptivity with localized wall blowing/suction." Acta Physica Sinica 64, no. 22 (2015): 224702. http://dx.doi.org/10.7498/aps.64.224702.

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35

Cruz, D. O. A., and F. T. Pinho. "Stokes’ second problem with wall suction or blowing for UCM fluids." Journal of Non-Newtonian Fluid Mechanics 157, no. 1-2 (March 2009): 66–78. http://dx.doi.org/10.1016/j.jnnfm.2008.09.006.

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36

Iollo, Angelo, and Luca Zannetti. "Trapped vortex optimal control by suction and blowing at the wall." European Journal of Mechanics - B/Fluids 20, no. 1 (January 2001): 7–24. http://dx.doi.org/10.1016/s0997-7546(00)00093-5.

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LI, Jian, Juan SHEN, and ChunHian LEE. "A micro-porous wall model for micro-blowing/suction flow system." Scientia Sinica Physica, Mechanica & Astronomica 44, no. 2 (2014): 221. http://dx.doi.org/10.1360/132013-158.

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38

Motozawa, Masaaki, Kaoru Iwamoto, Hirotomo Ando, Tetsuya Senda, and Yasuo Kawaguchi. "0305 Turbulent Drag Reduction with Blowing Polymer Solution from the Wall." Proceedings of the Fluids engineering conference 2009 (2009): 159–60. http://dx.doi.org/10.1299/jsmefed.2009.159.

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LUTOMIRSKI, STANISLAW, and MIROSLAW LADYSZ. "The wall thickness control for containers manufactured by the blowing method." Polimery 39, no. 01 (January 1994): 38–41. http://dx.doi.org/10.14314/polimery.1994.038.

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40

Labropulu, F., J. M. Dorrepaal, and O. P. Chandna. "Viscoelastic fluid flow impinging on a wall with suction or blowing." Mechanics Research Communications 20, no. 2 (March 1993): 143–53. http://dx.doi.org/10.1016/0093-6413(93)90021-f.

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41

Kumar, Abhishek, R. Dhanuskodi, R. Kaliappan, and K. Nandakumar. "BHEL Smart Wall Blowing System: New Product Development in Manufacturing Industry." Vikalpa: The Journal for Decision Makers 45, no. 4 (December 2020): 240–49. http://dx.doi.org/10.1177/02560909211005606.

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42

Lebedev, V. V., O. V. Lebedev, and A. E. Remizov. "Formation of film cooling on the turbine blade back and pressure side in the case of using V-shaped dimples." VESTNIK of Samara University. Aerospace and Mechanical Engineering 18, no. 4 (January 21, 2020): 96–105. http://dx.doi.org/10.18287/2541-7533-2019-18-4-96-105.

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Alongside the development of methods of intensifying convective heat transfer inside the blade, development of methods of local improvement of the efficiency of film cooling of the blade’s surface is still of immediate interest. The film is formed on the blade surface in conditions of high-camber shape and low initial velocity of the gas flow in the vicinity of the leading edge with its subsequent abrupt acceleration. The paper presents some data on the peculiarities of film formation on the back and pressure side of the blade in the vicinity of the leading edge. Experimental temperature distribution over the adiabatic wall was obtained with the use of a FLIR-E 64501 thermal imager. It was found that the conditions for the film formation on the blade back are more favorable than those on the pressure side. It manifests itself in the fact that optimal blowing parameters on the blade back are considerably lower than those on the pressure side. The use of V-shaped dimples located on the wall immediately behind the holes for blowing was suggested as a measure for local improvement of film cooling efficiency. The efficiencies of film cooling in the formation of a curtain, without the use and with the use of V-shaped dimples behind the holes for blowing were compared. Local improvement of efficiency and uniformity of film cooling distribution with the use of V-shaped dimples behind the holes for blowing was observed.

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Ravi, Duraisamy, and Kanjikovil Parammasivam. "Enhancing film cooling effectiveness in a gas turbine end-wall with a passive semi cylindrical trench." Thermal Science 23, no. 3 Part B (2019): 2013–23. http://dx.doi.org/10.2298/tsci170412001r.

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Computational studies were carried out in the end-wall of a linear cascade, of chosen blade profile, which is provided with one row of cylindrical film cooling holes inclined at 30o to the end wall. The CO gas was used as the coolant supplied through the film holes, 2 maintaining a blowing ratio of 0.6. The film cooling hole row was positioned at the leading edge of the cascade. The mainstream fluid was air and based on its properties at the cascade inlet, the flow was found turbulent. A semi cylindrical trench was placed at two positions upstream of the cascade leading edge and three positions downstream of it. ANSYS FLUENT 15.0 was used to compute the film cooling effectiveness of the cascade endwall. Trench positioned at a distance of twice that of film hole diameter, was found to show a highest increase of area averaged effectiveness value by 30.4% over the baseline. Further to this, the influence of the trench diameter was carried out where the trench with diameter twice that of film hole diameter was found to show a 31.3% increase of cooling effectiveness over the baseline. Studies on the influence of blowing ratio showed a highest increment of cooling effectiveness value by 43.5% over the baseline a blowing ratio of 1.2.

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McNeil, D. A., A. J. Addlesee, and J. Taylor. "The aerodynamic installation of optical fibres in telecommunication networks." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 216, no. 4 (November 1, 2002): 193–205. http://dx.doi.org/10.1243/095440802321194477.

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The installation of optical fibres for communication purposes is increasingly being carried out using a blowing technique. This study reviews the basis of the current design methods for this technique and proposes a new method based on a more traditional fluid mechanics approach. The method is used to demonstrate how far optical fibres can be blown and the stress levels likely to be encountered by them at various positions within their journey. The method will allow for future technological developments to be simulated by allowing for air drag on the fibre and the constraining tube wall to be treated differently.

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Zhang, Jingyu, Ping Jiang, Ce Yuan, and Xiaomin He. "Experimental Investigation on Flow Field Characteristics of Impinging-Film Cooling." International Journal of Aerospace Engineering 2021 (January 3, 2021): 1–10. http://dx.doi.org/10.1155/2021/8883194.

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This paper describes an experimental investigation on flow field characteristics of impinging-film cooling. Particle Image Velocimetry (PIV) technology has been applied to observe the effect of blowing ratio ( 0.04 ≤ M ≤ 0.3 ), temperature ratio ( 0.73 ≤ T u ≤ 0.91 ), jet-to-plate pitch ( 1.6 ≤ Z n ≤ 3.2 ), and spacing of impinging holes ( 1.94 ≤ Y n ≤ 3.5 ) on the flow field patterns in an impinging-film cooling test rig under atmospheric pressure. Experiment results show that the near-wall entrained vortex at the downstream of the slit moves downstream of the test rig as the blowing ratio increases, which increases the effective protection length of the film. While the vortex at the end of the inducting slab is stronger, this will increase the mixing in the shear layer. The radial size of the near-wall entrained vortex tends to decrease as the temperature ratio increases at the low blow ratio, and the entrainment effect on the downstream of the slit becomes smaller, causing the separation zone to decrease. Increasing the jet-to-plate pitch, the size of the near-wall entrained vortex increases, and the thickness of the film layer increases, this strengthens the separation effect of the near-wall airflow from the wall surface. The larger the spacing of the impinging holes, the more uneven the velocity distribution of the film.

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Liu, Peng, Juan-Juan Cai, Lei Zhao, and Ji-Huan He. "Micro-nanofibers with hierarchical structure by bubbfil-spinning." Thermal Science 19, no. 4 (2015): 1455–56. http://dx.doi.org/10.2298/tsci1504455l.

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Bubbfil spinning is used to fabricate micro/nanofibers with hierarchical structure. The wall of a polymer film is attenuated unevenly by a blowing air. The burst of the bubble results in film fragments with different thickness, as a result, different sizes of fibers are obtained.

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Gritsch, M., A. Schulz, and S. Wittig. "Adiabatic Wall Effectiveness Measurements of Film-Cooling Holes With Expanded Exits." Journal of Turbomachinery 120, no. 3 (July 1, 1998): 549–56. http://dx.doi.org/10.1115/1.2841752.

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This paper presents detailed measurements of the film-cooling effectiveness for three single, scaled-up film-cooling hole geometries. The hole geometries investigated include a cylindrical hole and two holes with a diffuser-shaped exit portion (i.e., a fan-shaped and a laid-back fan-shaped hole). The flow conditions considered are the crossflow Mach number at the hole entrance side (up to 0.6), the crossflow Mach number at the hole exit side (up to 1.2), and the blowing ratio (up to 2). The coolant-to-mainflow temperature ratio is kept constant at 0.54. The measurements are performed by means of an infrared camera system, which provides a two-dimensional distribution of the film-cooling effectiveness in the near field of the cooling hole down to x/D = 10. As compared to the cylindrical hole, both expanded holes show significantly improved thermal protection of the surface downstream of the ejection location, particularly at high blowing ratios. The laidback fan-shaped hole provides a better lateral spreading of the ejected coolant than the fan-shaped hole, which leads to higher laterally averaged film-cooling effectiveness. Coolant passage cross-flow Mach number and orientation strongly affect the flowfield of the jet being ejected from the hole and, therefore, have an important impact on film-cooling performance.

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Woodcock, James D., John E. Sader, and Ivan Marusic. "Induced flow due to blowing and suction flow control: an analysis of transpiration." Journal of Fluid Mechanics 690 (November 25, 2011): 366–98. http://dx.doi.org/10.1017/jfm.2011.441.

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AbstractIt has previously been demonstrated that the drag experienced by a Poiseuille flow in a channel can be reduced by subjecting the flow to a dynamic regime of blowing and suction at the walls of the channel (also known as ‘transpiration’). Furthermore, it has been found to be possible to induce a ‘bulk flow’, or steady motion through the channel, via transpiration alone. In this work, we derive explicit asymptotic expressions for the induced bulk flow via a perturbation analysis. From this we gain insight into the physical mechanisms at work within the flow. The boundary conditions used are of travelling sine waves at either wall, which may differ in amplitude and phase. Here it is demonstrated that the induced bulk flow results from the effect of convection. We find that the most effective arrangement for inducing a bulk flow is that in which the boundary conditions at either wall are equal in magnitude and opposite in sign. We also show that, for the bulk flow induced to be non-negligible, the wavelength of the boundary condition should be comparable to, or greater than, the height of the channel. Moreover, we derive the optimal frequency of oscillation, for maximising the induced bulk flow, under such boundary conditions. The asymptotic behaviour of the bulk flow is detailed within the conclusion. It is found, under certain caveats, that if the amplitude of the boundary condition is too great, the bulk flow induced will become dependent only upon the speed at which the boundary condition travels along the walls of the channel. We propose the conjecture that for all similar flows, if the magnitude of the transpiration is sufficiently great, the bulk flow will depend only upon the speed of the boundary condition.

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Li, Shao Hua, Hong Wei Qu, Mei Li Wang, and Ting Ting Guo. "An Experimental Investigation of Flow Characteristics Downstream of Discrete Film Cooling Holes on Turbine Blade Leading Edge." Advanced Materials Research 383-390 (November 2011): 5553–60. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.5553.

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The gas turbine blade was studied on the condition that the mainstream velocity was 10m/s and the Renolds number based on the chord length of the blade was 160000.The Hot-film anemometer was used to measure the two-dimension speed distribution along the downstream of the film cooling holes on the suction side and the pressure side. The conclusions are as follows: When the blowing ratio of the suction side and the pressure side increasing, the the mainstream and the jet injection mixing center raising. Entrainment flow occurs at the position where the blade surface with great curvature gradient, simultaneously the mixing flow has a wicked adhere to the wall. The velocity gradient of the u direction that on the suction side increase obviously, also the level of the wall adherence is better than the pressure side. With the x/d increasing, the velocity u that on the pressure side gradually become irregularly, also the secondary flow emerged near the wall region where the curvature is great. The blowing ratio on the suction side has a little influence on velocity v than that on the pressure side.

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Kim, Joongnyon, Kyoungyoun Kim, and Hyung Jin Sung. "Wall Pressure Fluctuations in a Turbulent Boundary Layer After Blowing or Suction." AIAA Journal 41, no. 9 (September 2003): 1697–704. http://dx.doi.org/10.2514/2.7315.

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