Film Cooling of Cylindrical Hole With a Downstream Short Crescent-Shaped Block

An, Bai-Tao; Li, Jianjun; Zhang, Chao; Zhou, Si-Jing

doi:10.1115/1.4007879

Cited by 31 publications

(21 citation statements)

References 33 publications

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“…By conducting a large eddy simulation (LES) study on a film cooling flow with a micro-ramp vortex generator, Shinn et al [6] found that the strength of counter-rotating vortex (CRV) structures in the coolant jet flows would be reduced substantially due to the exist of the vortex generator, resulting in a better film cooling effectiveness over the surface of interest. More recently, An et al [7] conducted an experimental study to investigate the film cooling performance behind a crescent block, and showed that the film cooling effectiveness would become better within certain range of blowing ratios due to the existence of the block. Na & Shih [8] performed a numerical study on a new film cooling configuration with a ramp placed upstream of a coolant injection hole, and found that the backward-facing ramp can greatly enhance the film cooling effectiveness over the surface of interest.…”

Section: Introductionmentioning

confidence: 99%

Improvements of film cooling effectiveness by using Barchan dune shaped ramps

Zhou

2016

International Journal of Heat and Mass Transfer

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In the present study, an experimental investigation was conducted to explore a novel film cooling design with Barchan-dune-shaped-ramp (BDSR) concept to augment the effectiveness of film cooling injection from discrete holes. Inspired by the unique shape of Barchan dunes commonly seen in deserts to prevent sand particles on the ground from being blown away by the oncoming airflow, the BDSR concept was proposed to enable the coolant streams exhausted from coolant injection holes stay more firmly over the surface of interest for improved film cooling performance. During the experiments, while coolant streams were injected from discrete circular holes on a flat test plate at an injection angle of 35 degrees, a row of BDSRs were mounted on the test plate at either downstream or upstream of the coolant injection holes for improved film cooling effectiveness. While a high-resolution Particle Image Velocimetry (PIV) system was used to conduct detailed flow field measurements to quantify the dynamic mixing process between the coolant jet streams and the mainstream flows over the test plate, a Pressure Sensitive Paint (PSP) technique was used to map the corresponding adiabatic film cooling effectiveness on the surface of interest based on a mass-flux analog to traditional temperature-based cooling effectiveness measurements. The cooling effectiveness data of the BDSR design were compared quantitatively against those of a conventional film cooling design without BDSR (i.e., baseline case) under the same test conditions in order to evaluate the effects of the BDSRs on the film cooling effectiveness over the surface of interest. The effects of the locations and height of the BDSRs in relation to the coolant injection holes on the film cooling effectiveness at different blowing ratios (i.e., the coolant-to-mainstream mass flux ratios) were examined quantitatively based on the PIV and PSP measurements. The detailed flow field measurements were correlated with the measured film cooling effectiveness distributions to elucidate the underlying physics in order to explore/optimize design paradigms for better film cooling protection of turbine blades from harsh environments.

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Section: Introductionmentioning

confidence: 99%

Improvements of film cooling effectiveness by using Barchan dune shaped ramps

Zhou

2016

International Journal of Heat and Mass Transfer

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“…The experimental work by Song et al [15] also revealed the down-wash effect of the induced vortices by the delta-shaped vortex generator at blowing ratios ranging from 0.5 to 1.5. In order to expand the lateral coolant coverage and alter the vortex structure around the hole, An et al [16] proposed a streamlined crescent-shaped block downstream the hole. The experimental results showed that the cooling effectiveness can be improved at blowing ratios ranging from 0.5 to 1.25.…”

Section: Introductionmentioning

confidence: 99%

Influence of streamwise position of crescent-shaped block on flat-plate film cooling characteristics

Zhang

Wang

2019

J Braz. Soc. Mech. Sci. Eng.

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Film cooling injection from discrete circular holes is widely used in gas turbines to reduce the heat load of the turbine blades. Placing a special designed structure upstream or downstream, the circular hole has been proven to be a new effective way to improve cooling effectiveness in recent years. In the present study, numerical investigations were performed on a row of circular holes over a flat plate with crescent-shaped blocks. Totally seven configurations without block, with blocks located at six streamwise positions including 6 times, 5 times, 4 times of hole diameter upstream, and 0.5 times, 1.5 times, 2.5 times of hole diameter downstream at blowing ratios of 0.5-1.5 were tested symmetrically. The Reynolds-averaged Navier-Stokes equations with the k-ω shear-stress transport model were solved. Flow fields, cooling effectiveness and aerodynamic losses were analyzed in detail. Although with different generation mechanism, additional vortex pair opposite to the counter-rotating vortex pair was generated by placing either an upstream or downstream block, which could finally improve the coolant lateral coverage and thus cooling effectiveness. The cooling performances and aerodynamic losses between configurations without block and with blocks at six streamwise positions were then compared. Finally, the optimal streamwise position of the block was recommended at various blowing ratios.

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“…For example, there is a large number of cooling cavity structures on the complex surface of a turbine blade in aero-engines [ 2 , 3 ]. These cavity structures have several three-dimensional structural characteristics, such as forward-expanded type and crescent type [ 4 ]. Meanwhile, their diameters are in a range from 300 to 500 μm.…”

Section: Introductionmentioning

confidence: 99%

Investigation of a Three-Dimensional Micro-Scale Sensing System Based on a Tapered Self-Assembly Four-Cores Fiber Bragg Grating Probe

Feng

Cui

Sun

et al. 2018

Sensors

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Three-dimensional micro-scale sensors are in high demand in the fields of metrology, precision manufacturing and industry inspection. To extend the minimum measurable dimension and enhance the accuracy, a tapered four-cores fiber Bragg grating (FBG) probe is proposed. The sensing model is built to investigate the micro-scale sensing characteristics of this method and the design of the tapered stylus is found to influence the accuracy. Therefore, a π/2 phase-shift point is introduced into the FBGs comprised in the probe to suppress spectrum distortion and improve accuracy. Then, the manufacturing method based on capillary self-assembly is proposed to form the probe and the critical length to form a square array for four cylindrical fibers is verified to be effective for the tapered fibers. Experimental results indicate that the design of the tapered stylus can extend the minimum measurable dimension by twofold and has nearly no influence on its sensitivity. The three-dimensional measurement repeatability is better than 31.1 nm and the stability is better than 200 nm within once measuring process. Furthermore, the measurement precision of the three-dimensional micro-scale measurement results is less than 150 nm. It would be widely used in measuring micro-scale features for industry inspection or metrology.

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Film Cooling of Cylindrical Hole With a Downstream Short Crescent-Shaped Block

Cited by 31 publications

References 33 publications

Improvements of film cooling effectiveness by using Barchan dune shaped ramps

Improvements of film cooling effectiveness by using Barchan dune shaped ramps

Influence of streamwise position of crescent-shaped block on flat-plate film cooling characteristics

Investigation of a Three-Dimensional Micro-Scale Sensing System Based on a Tapered Self-Assembly Four-Cores Fiber Bragg Grating Probe

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