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Journal articles on the topic 'Tip Gap'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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1

Laborde, R., P. Chantrel, and M. Mory. "Tip Clearance and Tip Vortex Cavitation in an Axial Flow Pump." Journal of Fluids Engineering 119, no. 3 (1997): 680–85. http://dx.doi.org/10.1115/1.2819298.

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A combined study of tip clearance and tip vortex cavitations in a pump-type rotating machine is presented. Cavitation patterns are observed and cavitation inception is determined for various gap heights, clearance and blade geometries, and rotor operating conditions. An optimum clearance geometry is seen to eliminate clearance cavitation when the clearance edge is rounded on the blade pressure side. The gap height has a strong effect on clearance cavitation inception, but the trends vary considerably when other parameters are also modified. The gap height and clearance geometry have less influ

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2

Dishart, P. T., and J. Moore. "Tip Leakage Losses in a Linear Turbine Cascade." Journal of Turbomachinery 112, no. 4 (1990): 599–608. http://dx.doi.org/10.1115/1.2927700.

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An investigation of tip leakage flow and its effects on loss production was performed on a large-scale linear turbine cascade having a tip gap measuring 2.1 percent of the blade height. The flow exiting the tip gap was measured to determine the losses incurred within the tip gap and the secondary kinetic energy due to tip leakage. Additional measurements, 40 percent of an axial chord downstream of the blade trailing edges, showed the development of the leakage flow and the overall cascade losses. At the downstream location, the additional loss due to tip leakage was found to be the sum of the

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3

Moore, J., J. G. Moore, G. S. Henry, and U. Chaudhry. "Flow and Heat Transfer in Turbine Tip Gaps." Journal of Turbomachinery 111, no. 3 (1989): 301–9. http://dx.doi.org/10.1115/1.3262269.

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The effects of Reynolds number on flow through a tip gap are investigated by performing laminar flow calculations for an idealized two-dimensional tip gap geometry. The results of the calculations aid in understanding and reconciliation of low Much number turbine tip gap measurements, which range in tip gap Reynolds number from 100 to 10,000. For the higher Reynolds numbers, both the calculations and the measurements show a large separation off the sharp edge of the blade tip corner. For a high Reynolds number, fully turbulent flow calculations were also made. These also show a large separatio

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4

Kurokawa, Shu, and Akira Sakai. "Gap dependence of the tip-sample capacitance." Journal of Applied Physics 83, no. 12 (1998): 7416–23. http://dx.doi.org/10.1063/1.367985.

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5

Ma, Ruolong, and William J. Devenport. "Tip Gap Effects on the Unsteady Behavior of a Tip Leakage Vortex." AIAA Journal 45, no. 7 (2007): 1713–24. http://dx.doi.org/10.2514/1.13536.

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6

Key, Nicole L., and Tony Arts. "Comparison of Turbine Tip Leakage Flow for Flat Tip and Squealer Tip Geometries at High-Speed Conditions." Journal of Turbomachinery 128, no. 2 (2004): 213–20. http://dx.doi.org/10.1115/1.2162183.

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The tip leakage flow characteristics for flat and squealer turbine tip geometries are studied in the von Karman Institute Isentropic Light Piston Compression Tube facility, CT-2, at different Reynolds and Mach number conditions for a fixed value of the tip gap in a nonrotating, linear cascade arrangement. To the best knowledge of the authors, these are among the very few high-speed tip flow data for the flat tip and squealer tip geometries. Oil flow visualizations and static pressure measurements on the blade tip, blade surface, and corresponding endwall provide insight to the structure of the

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7

Kameier, F., and W. Neise. "Experimental Study of Tip Clearance Losses and Noise in Axial Turbomachines and Their Reduction." Journal of Turbomachinery 119, no. 3 (1997): 460–71. http://dx.doi.org/10.1115/1.2841145.

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An experimental study is described to investigate the negative effects of the tip clearance gap on the aerodynamic and acoustic performance of axial turbomachines. In addition to the increased broadband levels reported in the literature when the tip clearance is enlarged, significant level increases were observed within narrow frequency bands below the blade passing frequency. Measurements of the pressure and velocity fluctuations in the vicinity of the blade tips reveal that the tip clearance noise is associated with a rotating flow instability at the blade tip, which in turn is only present

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8

Christophel, J. R., K. A. Thole, and F. J. Cunha. "Cooling the Tip of a Turbine Blade Using Pressure Side Holes—Part II: Heat Transfer Measurements." Journal of Turbomachinery 127, no. 2 (2005): 278–86. http://dx.doi.org/10.1115/1.1811096.

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The clearance gap between a turbine blade tip and its associated shroud allows leakage flow across the tip from the pressure side to the suction side of the blade. Understanding how this leakage flow affects heat transfer is critical in extending the durability of a blade tip, which is subjected to effects of oxidation and erosion. This paper is the second of a two-part series that discusses the augmentation of tip heat transfer coefficients as a result of blowing from film-cooling holes placed along the pressure side of a blade and from dirt purge holes placed on the tip. For the experimental

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9

Lee, Sang Woo, and Seon Ung Kim. "Tip gap height effects on the aerodynamic performance of a cavity squealer tip in a turbine cascade in comparison with plane tip results: part 1—tip gap flow structure." Experiments in Fluids 49, no. 5 (2010): 1039–51. http://dx.doi.org/10.1007/s00348-010-0848-6.

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10

Moore, J., and J. S. Tilton. "Tip Leakage Flow in a Linear Turbine Cascade." Journal of Turbomachinery 110, no. 1 (1988): 18–26. http://dx.doi.org/10.1115/1.3262162.

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An experimental and analytical study of flow in the tip clearance gap of a linear turbine rotor blade cascade has been performed. Measurements of wall static pressures and flow velocities are used to verify a flow model involving a vena contracta, near the tip gap entrance, followed by flow mixing to fill the gap. A frequently referenced potential flow theory for flow into a tip gap is found to be in error and the correct theory is shown to model the unloading along the pressure surface of the blade and the endwall static pressure distribution up to the vena contracta accurately. A combined po

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11

Sjolander, S. A., and D. Cao. "Measurements of the Flow in an Idealized Turbine Tip Gap." Journal of Turbomachinery 117, no. 4 (1995): 578–84. http://dx.doi.org/10.1115/1.2836571.

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To gain further insights into the details of the tip-gap flow in axial turbines, a test section has been constructed with a single idealized, large-scale tip gap. The single “blade” forms a circular arc with 90 deg of turning and has a constant thickness of 78 mm. For a plain, flat tip four clearances have been examined, varying from 0.292 to 0.667 of the blade thickness (corresponding to physical gap heights of 22.8 to 52.1 mm). The large proportions made it possible to obtain very detailed measurements inside the gap. The paper discusses the structure of the gap flow in some detail. One new

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12

Saleh, Zainab, Eldad J. Avital, and Theodosios Korakianitis. "Effect of in-service burnout on the transonic tip leakage flows over flat tip model." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 234, no. 5 (2019): 655–69. http://dx.doi.org/10.1177/0957650919877057.

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Un-shrouded turbine blades are more common than shrouded ones in gas turbine aero-engines since they reduce the weight and avoid the centrifugal loading caused by the blades’ shrouds. Despite these important advantages, the absence of the shroud leads to leakage flows across the tip gap and exposes the blade tip to high thermal load and thermal damages. In addition, the leakage flows can contribute up to 30% of the aerodynamic loss in a turbine stage. In this study, the effect of in-service burnout is explored using a fundamental flat tip model of a high-pressure gas turbine blade. This invest

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13

Christophel, J. R., E. Couch, K. A. Thole, and F. J. Cunha. "Measured Adiabatic Effectiveness and Heat Transfer for Blowing From the Tip of a Turbine Blade." Journal of Turbomachinery 127, no. 2 (2005): 251–62. http://dx.doi.org/10.1115/1.1811095.

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The clearance gap between the tip of a turbine blade and the shroud has an inherent leakage flow from the pressure side to the suction side of the blade. This leakage flow of combustion gas and air mixtures leads to severe heat transfer rates on the blade tip of the high-pressure turbine. As the thermal load to the blade increases, blade alloy oxidation and erosion rates increase thereby adversely affecting component life. The subject of this paper is the cooling effectiveness levels and heat transfer coefficients that result from blowing through two holes placed in the forward region of a bla

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14

Nasir, Hasan, Srinath V. Ekkad, David M. Kontrovitz, Ronald S. Bunker, and Chander Prakash. "Effect of Tip Gap and Squealer Geometry on Detailed Heat Transfer Measurements Over a High Pressure Turbine Rotor Blade Tip." Journal of Turbomachinery 126, no. 2 (2004): 221–28. http://dx.doi.org/10.1115/1.1731416.

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The present study explores the effects of gap height and tip geometry on heat transfer distribution over the tip surface of a HPT first-stage rotor blade. The pressure ratio (inlet total pressure to exit static pressure for the cascade) used was 1.2, and the experiments were run in a blow-down test rig with a four-blade linear cascade. A transient liquid crystal technique was used to obtain the tip heat transfer distributions. Pressure measurements were made on the blade surface and on the shroud for different tip geometries and tip gaps to characterize the leakage flow and understand the heat

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15

Yaras, M. I., and S. A. Sjolander. "Effects of Simulated Rotation on Tip Leakage in a Planar Cascade of Turbine Blades: Part I—Tip Gap Flow." Journal of Turbomachinery 114, no. 3 (1992): 652–59. http://dx.doi.org/10.1115/1.2929189.

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The paper presents further results from a continuing study on tip leakage in axial turbines. Rotation has been simulated in a linear cascade test section by using a moving-belt tip wall. Measurements were made inside the tip gap with a three-hole pressure probe for a clearance size of 3.8 percent of the blade chord. Two wall speeds are considered and the results are compared with the case of no rotation. As in other experiments, significant reduction in the gap mass flow rate is observed due to the relative motion. The detailed nature of the measurements allows the dominant physical mechanism

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16

Wheeler, Andrew P. S., and Richard D. Sandberg. "Numerical investigation of the flow over a model transonic turbine blade tip." Journal of Fluid Mechanics 803 (August 17, 2016): 119–43. http://dx.doi.org/10.1017/jfm.2016.478.

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Direct numerical simulations (DNS) are used to investigate the unsteady flow over a model turbine blade tip at engine-scale Reynolds and Mach numbers. The DNS are performed with an in-house multiblock structured compressible Navier–Stokes solver. The particular case of a transonic tip flow is studied since previous work has suggested that compressibility has an important effect on the turbulent nature of the separation bubble at the inlet to the tip–casing gap and subsequent flow reattachment. The flow is simulated over an idealized tip geometry where the tip gap is represented by a constant-a

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17

Papa, M., R. J. Goldstein, and F. Gori. "Effects of Tip Geometry and Tip Clearance on the Mass/Heat Transfer From a Large-Scale Gas Turbine Blade." Journal of Turbomachinery 125, no. 1 (2003): 90–96. http://dx.doi.org/10.1115/1.1529190.

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An experimental investigation has been performed to measure average and local mass transfer coefficients on the tip of a gas turbine blade using the naphthalene sublimation technique. The heat/mass transfer analogy can be applied to obtain heat transfer coefficients from the measured mass transfer data. Flow visualization on the tip surface is provided using an oil dot technique. Two different tip geometries are considered: a squealer tip and a winglet-squealer tip having a winglet on the pressure side and a squealer on the suction side of the blade. Measurements have been taken at tip clearan

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18

Chima, R. V. "Calculation of Tip Clearance Effects in a Transonic Compressor Rotor." Journal of Turbomachinery 120, no. 1 (1998): 131–40. http://dx.doi.org/10.1115/1.2841374.

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The flow through the tip clearance region of a transonic compressor rotor (NASA rotor 37) was computed and compared to aerodynamic probe and laser anemometer data. Tip clearance effects were modeled both by gridding the clearance gap and by using a simple periodicity model across the ungridded gap. The simple model was run with both the full gap height, and with half the gap height to simulate a vena-contracta effect. Comparisons between computed and measured performance maps and downstream profiles were used to validate the models and to assess the effects of gap height on the simple clearanc

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19

Kang, Dong Bum, Hyun Suk Moon, and Sang Woo Lee. "Effect of Tip Gap Height on Heat/Mass Transfer over a Cavity Squealer Tip." Journal of Fluid Machinery 16, no. 6 (2013): 19–25. http://dx.doi.org/10.5293/kfma.2013.16.6.019.

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20

You, Donghyun, Meng Wang, Parviz Moin, and Rajat Mittal. "Effects of tip-gap size on the tip-leakage flow in a turbomachinery cascade." Physics of Fluids 18, no. 10 (2006): 105102. http://dx.doi.org/10.1063/1.2354544.

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21

Bindon, J. P., and G. Morphis. "The Development of Axial Turbine Leakage Loss for Two Profiled Tip Geometries Using Linear Cascade Data." Journal of Turbomachinery 114, no. 1 (1992): 198–203. http://dx.doi.org/10.1115/1.2927985.

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To assess the possibility of tip clearance loss reduction and to explore the nature and origin of tip clearance loss, blade tip geometries that reduce the roughly 40 percent of total loss occurring within the gap were studied. The shapes investigated aimed at reducing or avoiding the gap separation bubble thought to contribute significantly to both internal gap loss and to the endwall mixing loss. It was found that radiusing and contouring the blade at gap inlet eliminated the separation bubble and reduced the internal gap loss but created a higher mixing loss to give almost unchanged overall

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22

Тренькин, А. А., К. И. Алмазова, А. Н. Белоногов та ін. "Динамика начальной фазы искрового и диффузного разрядов в воздухе в промежутке острие--плоскость при различных параметрах острийного электрода". Журнал технической физики 89, № 4 (2019): 512. http://dx.doi.org/10.21883/jtf.2019.04.47305.309-18.

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AbstractDynamics of the initial stage of discharge in air is studied at atmospheric pressure in a point–plane gap at different parameters of the tip electrode and lengths of the interelectrode gap. Spark or diffuse discharges are implemented in experiments depending on the length of the interelectrode gap. Shadow photography is used to show that, for all electrodes in the experiments, the discharge channels represent multiple microchannels that develop from the tip and close the discharge gap.

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23

Oliveira, Rafael M., and Eckart Meiburg. "Miscible displacements in Hele-Shaw cells: three-dimensional Navier–Stokes simulations." Journal of Fluid Mechanics 687 (October 12, 2011): 431–60. http://dx.doi.org/10.1017/jfm.2011.367.

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AbstractThree-dimensional Navier–Stokes simulations of viscously unstable, miscible Hele-Shaw displacements are discussed. Quasisteady fingers are observed whose tip velocity increases with the Péclet number and the unfavourable viscosity ratio. These fingers are widest near the tip, and become progressively narrower towards the root. The film of resident fluid left behind on the wall decreases in thickness towards the finger tip. The simulations reveal the detailed mechanism by which the initial spanwise vorticity of the base flow, when perturbed, gives rise to the cross-gap vorticity that dr

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24

Régis, Koch, Sanjosé Marlène, and Moreau Stéphane. "Aerodynamic investigation of a linear cascade with tip gap using large-eddy simulation." Journal of the Global Power and Propulsion Society 5 (April 7, 2021): 39–49. http://dx.doi.org/10.33737/jgpps/133601.

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The flow in a linear compressor cascade with tip gap is simulated using a wall-resolved compressible Large-Eddy Simulation. The cascade is based on the Virginia Tech Low Speed Cascade Wind Tunnel. The Reynolds number based on the chord is 3.88 x 10⁵ and the Mach number is 0.07. The gap considered in this study is 4.0 mm (2.9% of axial chord). An aerodynamic analysis of the tip-leakage flow allow us identifying the main mechanisms responsible for the development and the convection of the tip-leakage vortex downstream of the cascade. A region of high turbulence and vorticity levels is located al

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25

He, Lu, Mahfujur Rahaman, Teresa I. Madeira, and Dietrich R. T. Zahn. "Understanding the Role of Different Substrate Geometries for Achieving Optimum Tip-Enhanced Raman Scattering Sensitivity." Nanomaterials 11, no. 2 (2021): 376. http://dx.doi.org/10.3390/nano11020376.

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Tip-enhanced Raman spectroscopy (TERS) has experienced tremendous progress over the last two decades. Despite detecting single molecules and achieving sub-nanometer spatial resolution, attaining high TERS sensitivity is still a challenging task due to low reproducibility of tip fabrication, especially regarding very sharp tip apices. Here, we present an approach for achieving strong TERS sensitivity via a systematic study of the near-field enhancement properties in the so-called gap-mode TERS configurations using the combination of finite element method (FEM) simulations and TERS experiments.

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26

Kim, Y. W., and D. E. Metzger. "Heat Transfer and Effectiveness on Film Cooled Turbine Blade Tip Models." Journal of Turbomachinery 117, no. 1 (1995): 12–21. http://dx.doi.org/10.1115/1.2835630.

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In unshrouded axial turbine stages, a small but generally unavoidable clearance between the blade tips and the stationary outer seal allows a clearance gap leakage flow to be driven across the blade tip by the pressure-to-suction side pressure difference. In modern high-temperature machines, the turbine blade tips are often a region prone to early failure because of the presence of hot gases in the gap and the resultant added convection heating that must be counteracted by active blade cooling. The blade tip region, particularly near the trailing edge, is often very difficult to cool adequatel

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27

Christophel, J. R., K. A. Thole, and F. J. Cunha. "Cooling the Tip of a Turbine Blade Using Pressure Side Holes—Part I: Adiabatic Effectiveness Measurements." Journal of Turbomachinery 127, no. 2 (2005): 270–77. http://dx.doi.org/10.1115/1.1812320.

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Durability of turbine blade tips has been and continues to be challenging, particularly since increasing turbine inlet temperatures is the driver for improving turbine engine performance. As a result, cooling methods along the blade tip are crucial. Film-cooling is one typically used cooling method whereby coolant is supplied through holes placed along the pressure side of a blade. The subject of this paper is to evaluate the adiabatic effectiveness levels that occur on the blade tip through blowing coolant from holes placed near the tip of a blade along the pressure side. A range of blowing r

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28

Fei, Zhaodan, Rui Zhang, Hui Xu, and Tong Mu. "Numerical analysis of the groove effect on the tip leakage vortex cavitating flow." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 234, no. 6 (2019): 836–47. http://dx.doi.org/10.1177/0957650919884192.

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In this paper, the groove effect on the tip leakage vortex cavitating flow characteristics of a simplified NACA0009 hydrofoil with tip gap is studied. Considering local rotation characteristics and curvature effects of the tip leakage vortex flow, the rotation-curvature corrected shear-stress-transport turbulence model is applied to simulate the time-averaged turbulent flow. The Zwart–Gerber–Belamri cavitation model is used to simulate the cavitating flow. The results show that the groove could affect the tip leakage vortex cavitating flow. The groove enhances the interaction between the tip l

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29

Packard, W. E., J. D. Dow, H. Rohrer, J. W. Palmour, C. H. Carter, and R. Nicolaides. "Scanning Tunneling Microscopy with a Large-Gap Semiconductor Tip." Europhysics Letters (EPL) 26, no. 2 (1994): 97–102. http://dx.doi.org/10.1209/0295-5075/26/2/004.

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30

Grilliat, Julien, and Marc C. Jacob. "Aeroacoustics of a low Mach number tip‐gap flow." Journal of the Acoustical Society of America 123, no. 5 (2008): 3540. http://dx.doi.org/10.1121/1.2934523.

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31

Dreyer, M., J. Decaix, C. Münch-Alligné, and M. Farhat. "Mind the gap - tip leakage vortex in axial turbines." IOP Conference Series: Earth and Environmental Science 22, no. 5 (2014): 052023. http://dx.doi.org/10.1088/1755-1315/22/5/052023.

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32

Montomoli, F., M. Massini, and S. Salvadori. "Geometrical uncertainty in turbomachinery: Tip gap and fillet radius." Computers & Fluids 46, no. 1 (2011): 362–68. http://dx.doi.org/10.1016/j.compfluid.2010.11.031.

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33

Newton, P. J., G. D. Lock, S. K. Krishnababu, et al. "Heat Transfer and Aerodynamics of Turbine Blade Tips in a Linear Cascade." Journal of Turbomachinery 128, no. 2 (2004): 300–309. http://dx.doi.org/10.1115/1.2137745.

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Local measurements of the heat transfer coefficient and pressure coefficient were conducted on the tip and near tip region of a generic turbine blade in a five-blade linear cascade. Two tip clearance gaps were used: 1.6% and 2.8% chord. Data was obtained at a Reynolds number of 2.3×105 based on exit velocity and chord. Three different tip geometries were investigated: A flat (plain) tip, a suction-side squealer, and a cavity squealer. The experiments reveal that the flow through the plain gap is dominated by flow separation at the pressure-side edge and that the highest levels of heat transfer

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34

Pradeep, A. M., R. N. Chiranthan, Debarshi Dutta, and Bhaskar Roy. "Effect of Rotor Tip Gap Variation at the Rear Stages of an Axial Flow Compressor." Applied Mechanics and Materials 225 (November 2012): 233–38. http://dx.doi.org/10.4028/www.scientific.net/amm.225.233.

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In this paper, detailed analysis of the tip flow of an axial compressor rotor blade has been carried out using the commercial CFD package ANSYS CFX. The rotor blade was designed such that it is reminiscent of the rear stages of a multi-stage axial compressor. The effects of varying tip gaps are studied using CFD simulations for overall pressure rise and flow physics of the tip flow at the design point and near the peak pressure point. Rig tests of a low speed research compressor rotor with 3% tip clearance provided characteristics plots for validation of the CFD results. With increase in clear

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35

Zhao, Yu, Yutong Jiang, Xiaolong Cao, and Guoyu Wang. "Study on tip leakage vortex cavitating flows using a visualization method." Modern Physics Letters B 32, no. 01 (2018): 1850003. http://dx.doi.org/10.1142/s0217984918500033.

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Experimental investigations of unsteady cavitating flows in a hydrofoil tip leakage region with different gap sizes are conducted to highlight the development of gap cavitation. The experiments were taken in a closed cavitation tunnel, during which high-speed camera had been used to capture the cavitation patterns. A new visualization method based on image processing was developed to capture time-dependent cavitation patterns. The results show that the visualization method can effectively capture the cavitation patterns in the tip region, including both the attached cavity in the gap and the t

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36

Gao, Jie, Ming Wei, Pengfei Liu, Guoqiang Yue, and Qun Zheng. "Improved clearance designs to minimize aerodynamic losses in a variable geometry turbine vane cascade." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 17 (2017): 3085–101. http://dx.doi.org/10.1177/0954406217729716.

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Variable geometry turbine exists in small mobile gas turbines or some marine gas turbines to enhance the part-load performance. However, there are efficiency penalties associated with the vane partial gap, which is needed for the movement of variable vanes. This paper investigates the vane-end clearance leakage flow for a flat tip, a cavity tip, a winglet tip, a tip with passive injection, and a cavity-winglet tip to assess the possibility of minimizing vane-end clearance losses in a variable geometry turbine cascade. First, calculations were done at the test rig conditions for comparison with

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37

Kim, Y. W., J. P. Downs, F. O. Soechting, W. Abdel-Messeh, G. D. Steuber, and S. Tanrikut. "Darryl E. Metzger Memorial Session Paper: A Summary of the Cooled Turbine Blade Tip Heat Transfer and Film Effectiveness Investigations Performed by Dr. D. E. Metzger." Journal of Turbomachinery 117, no. 1 (1995): 1–11. http://dx.doi.org/10.1115/1.2835638.

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The clearance gap between the stationary outer air seal and blade tips of an axial turbine allows a clearance gap leakage flow to be driven through the gap by the pressure-to-suction side pressure difference. The presence of strong secondary flows on the pressure side of the airfoil tends to deliver air from the hottest regions of the mainstream to the clearance gap. The blade tip region, particularly near the trailing edge, is very difficult to cool adequately with blade internal coolant flow. In this case, film cooling injection directly onto the blade tip region can be used in an attempt to

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38

Farge, T. Z., M. W. Johnson, and T. M. A. Maksoud. "Tip Leakage in a Centrifugal Impeller." Journal of Turbomachinery 111, no. 3 (1989): 244–49. http://dx.doi.org/10.1115/1.3262262.

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The effects of tip leakage have been studied using a 1-m-dia shrouded impeller where a leakage gap is left between the inside of the shroud and the impeller blades. A comparison is made with results for the same impeller where the leakage gap is closed. The static pressure distribution is found to be almost unaltered by the tip leakage, but significant changes in the secondary velocities alter the size and position of the passage wake. Low-momentum fluid from the suction-side boundary layer of the measurement passage and tip leakage fluid from the neighboring passage contribute to the formatio

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39

Langari, Bahareh, Saeed Vaseghi, Ales Prochazka, Babak Vaziri, and Farzad Tahmasebi Aria. "Edge-Guided Image Gap Interpolation Using Multi-Scale Transformation." IEEE Transactions on Image Processing 25, no. 9 (2016): 4394–405. http://dx.doi.org/10.1109/tip.2016.2590825.

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40

Jinhui Tang, Zheng-Jun Zha, Dacheng Tao, and Tat-Seng Chua. "Semantic-Gap-Oriented Active Learning for Multilabel Image Annotation." IEEE Transactions on Image Processing 21, no. 4 (2012): 2354–60. http://dx.doi.org/10.1109/tip.2011.2180916.

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41

Teng, Shuye, Je-Chin Han, and G. M. S. Azad. "Detailed Heat Transfer Coefficient Distributions on a Large-Scale Gas Turbine Blade Tip." Journal of Heat Transfer 123, no. 4 (2000): 803–9. http://dx.doi.org/10.1115/1.1373655.

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Measurements of detailed heat transfer coefficient distributions on a turbine blade tip were performed in a large-scale, low-speed wind tunnel facility. Tests were made on a five-blade linear cascade. The low-speed wind tunnel is designed to accommodate the 107.49 deg turn of the blade cascade. The mainstream Reynolds number based on cascade exit velocity was 5.3×105. Upstream unsteady wakes were simulated using a spoke-wheel type wake generator. The wake Strouhal number was kept at 0 or 0.1. The central blade had a variable tip gap clearance. Measurements were made at three different tip gap

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Lu, X., J. Zhu, and W. Chu. "Numerical and experimental investigation of stepped tip gap effects on a subsonic axial-flow compressor rotor." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 219, no. 8 (2005): 605–15. http://dx.doi.org/10.1243/095765005x31324.

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This article investigates the flow field at the tip region of compressor rotor. In particular, the effect of stepped tip gaps on the performance and flow field of axial compressor was reviewed using experimental and computational methods. An axial compressor rotor with no inlet guide vanes was tested under subsonic conditions. A parametric study of clearance levels and step profiles was performed using eight different casing geometries. This study was aimed at comparing compressor performance in specified configurations. The experimental results showed that the inclusion of stepped tip gaps wi

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Metzger, D. E., M. G. Dunn, and C. Hah. "Turbine Tip and Shroud Heat Transfer." Journal of Turbomachinery 113, no. 3 (1991): 502–7. http://dx.doi.org/10.1115/1.2927902.

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Unshrouded blades of axial turbine stages move in close proximity to the stationary outer seal, or shroud, of the turbine housing. The pressure difference between the concave and convex sides of the blade drives a leakage flow through the gap between the moving blade tip and adjacent wall. This clearance leakage flow and accompanying heat transfer are of interest because of long obvious effects on aerodynamic performance and structural durability, but understanding of its nature and influences has been elusive. Previous studies indicate that the leakage through the gap is mainly a pressure-dri

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Saunders, Stephen G. "Service employee evaluations of customer tips: an expectations-disconfirmation tip gap approach." Journal of Service Theory and Practice 25, no. 6 (2015): 796–812. http://dx.doi.org/10.1108/jstp-07-2014-0148.

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Purpose – Many service employees rely on non-contractual voluntary customer tips as a major source of their income. The purpose of this paper is to empirically test the relationship between the service employee’s cognitive evaluation of the tip (expectations-disconfirmation tip gap), affective state (AS) and displayed emotions (DE) toward customers in the workplace. Design/methodology/approach – An experimental, between-subjects, scenario-based research design was conducted on 107 waiters in the US restaurant industry. A simple mediation model was first tested, before testing a more complex mo

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Zhong, Fangpan, and Chao Zhou. "Tip gap size effects on thermal performance of cavity-winglet tips in transonic turbine cascade with endwall motion." Journal of the Global Power and Propulsion Society 1 (June 27, 2017): CR5JBC. http://dx.doi.org/10.22261/cr5jbc.

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AbstractThe thermal performance of two cavity-winglet tips with endwall motion is investigated in a transonic high pressure turbine cascade, which operates at an engine representative exit Mach number of 1.2 and an exit Reynolds number of 1.7 × 106. The numerical method is first validated with experimental data and then used to investigate blade heat transfer at three different tip clearances of 1.1, 2.1 and 3.1% chord. The effects of relative endwall motion are considered. The present results show that as the size of the tip gap increases, the heat transfer coefficient and heat load on the ti

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Feng, Wuheng, Yuxin Zhao, Qiancheng Wang, and Chenglong Wang. "Influence of the Reynolds Number on Transonic Tip Flow." International Journal of Aerospace Engineering 2020 (November 7, 2020): 1–11. http://dx.doi.org/10.1155/2020/8841093.

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The tip flows in modern gas turbines are primarily transonic under realistic conditions and significantly impact the overall thrust performance and safety of the turbines. This study is aimed at providing a deeper understanding of the mechanisms underlying and controlling the tip flow characteristics. Particle image velocimetry (PIV) and Schlieren and oil flow visualizations were performed to reveal the basic structure of the tip flow fields. A computational fluid dynamics model was developed, and the experimental results validated its accuracy. FLUENT 18.0 was employed to apply the Spalart-Al

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Liu, Yun Long, Jian Ping Tan, and Yan Xu. "RC Snubber Circuit of Large Gap Magnetic Driven System." Applied Mechanics and Materials 105-107 (September 2011): 2076–79. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.2076.

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Based on the single chip microcomputer (SCM) control theory, the control circuit of magnetic driving system of axial flow blood pump is designed. For the easy damage of TIP 122, which is used as the power switch of control circuit, RC snubber circuit is designed by analysis and experiments. And then an optimal matching of the key parameters is obtained to solve the security problem of the TIP 122. The experimental results show that the RC snubber circuit can improve the reliability and stability of the driving system, and to provide an experimental foundation for the further studies.

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El-Batsh, Hesham M., and Magdy Bassily Hanna. "An Investigation on the Effect of Endwall Movement on the Tip Clearance Loss Using Annular Turbine Cascade." International Journal of Rotating Machinery 2011 (2011): 1–11. http://dx.doi.org/10.1155/2011/489150.

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The aerodynamic losses in gas turbines are mainly caused by profile loss secondary flow, and tip leakage loss. This study focuses on tip leakage flow of high-pressure turbine stages. An annular turbine cascade was constructed with fixed blades on the casing, and the distance between blade tip and the hub was considered as tip clearance gap. The effect of endwall movement on loss mechanism was investigated by using experimental and numerical techniques. The measurements were obtained while the hub was fixed but the numerical calculations were carried out for both stationary and moving cascades.

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Kwak, Jae Su, and Je-Chin Han. "Heat Transfer Coefficients and Film Cooling Effectiveness on the Squealer Tip of a Gas Turbine Blade." Journal of Turbomachinery 125, no. 4 (2003): 648–57. http://dx.doi.org/10.1115/1.1622712.

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Experimental investigations were performed to measure the detailed heat transfer coefficients and film cooling effectiveness on the squealer tip of a gas turbine blade in a five-bladed linear cascade. The blade was a two-dimensional model of a first stage gas turbine rotor blade with a profile of the GE-E3 aircraft gas turbine engine rotor blade. The test blade had a squealer (recessed) tip with a 4.22% recess. The blade model was equipped with a single row of film cooling holes on the pressure side near the tip region and the tip surface along the camber line. Hue detection based transient li

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Bindon, J. P. "The Measurement and Formation of Tip Clearance Loss." Journal of Turbomachinery 111, no. 3 (1989): 257–63. http://dx.doi.org/10.1115/1.3262264.

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The detailed development of tip clearance loss from the leading to trailing edge of a linear turbine cascade was measured and the contributions made by mixing, internal gap shear flow, and endwall/ secondary flow were identified, separated, and quantified for the first time. Only 13 percent of the overall loss arises from endwall/secondary flow and of the remaining 87 percent, 48 percent is due to mixing and 39 percent is due to internal gap shear. All loss formation appears to be dominated by phenomena connected with the gap separation bubble. Flow established within the bubble by the pressur

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