Flow Field Investigations on the Effect of Rib Placement in a Cooling Channel With Film-Cooling

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
Martin Kunze ◽  
Konrad Vogeler
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Film Cooling ◽  
Laser Doppler Anemometry ◽  
Measurement Techniques ◽  
Experimental Investigations ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Field Investigations ◽  
Small Influence

This paper presents experimental investigations on flat plate film-cooling in combination with a ribbed cooling channel. The effect of rib placement on the film-cooling injection and the flow in the cooling channel was studied. The velocity fields were measured using optical laser measurement techniques including LDA (laser doppler anemometry) and PIV (particle image velocimetry). A row of three cylindrical film holes is placed in the center rib segment of the cooling channel. The dimensionless rib-to-hole position s/D is varied from 4.5 to 10.5. The investigations are conducted at isothermal conditions for a variation of the coolant Reynolds number Rec,Dh from 10,000 up to 60,000 and for three blowing rates M = 0.5, 0.75, and 1.00. The flow field results for the film-cooling injection showed only a small influence of the rib placement. Due to different coolant-to-main flow pressure ratios across the row, a slight nonuniform share of coolant flow occurs. Intense streamwise mixing and decay of the turbulence in the film jet was observed within the first 10 hole diameters. Enhancement of the turbulence intensity inside the jet core was found with increasing coolant Reynolds numbers. Inside the internal cooling channel, the flow field showed significant influence of the rib position which is most pronounced at low Reynolds number (Rec,Dh = 10,000) and high blowing ratios (M = 1.0). The effect becomes significantly smaller when the Reynolds number is increased. This is mainly attributed to the strongly increasing channel mass flow which equals to a decreasing suction ratio SR = uh/uc of the holes. The experimental results are compared to comprehensive numerical simulations.

Flow Field Investigations on the Effect of Rib Placement in a Cooling Channel With Film-Cooling

2013 ◽  
Author(s):  
Martin Kunze ◽  
Konrad Vogeler
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Film Cooling ◽  
Laser Doppler Anemometry ◽  
Measurement Techniques ◽  
Experimental Investigations ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Field Investigations ◽  
Small Influence

This paper presents experimental investigations on flat plate film-cooling in combination with a ribbed cooling channel. The effect of rib placement on the film-cooling injection and the flow in the cooling channel was studied. The velocity fields were measured using optical laser measurement techniques as LDA (Laser-Doppler-Anemometry) and PIV (Particle-Image-Velocimetry). A row of three cylindrical film holes is placed in the center rib segment of the cooling channel. The dimensionless rib-to-hole position s/D is varied from 4.5 to 10.5. The investigations are conducted at isothermal conditions for a variation of the coolant Reynolds number Rec,Dh from 10000 up to 60000 and for three blowing rates M = 0.5, 0.75 and 1.00. The flow field results for the film-cooling injection showed only small influence of the rib placement. Due to different coolant-to-main flow pressure ratios across the row, a slight non-uniform share of coolant flow occurs. Intense streamwise mixing and decay of the turbulence in the film jet was observed within the first 10 hole diameters. Enhancement of the turbulence intensity inside the jet core was found with increasing coolant Reynolds numbers. Inside the internal cooling channel, the flow field showed significant influence of the rib position which is most pronounced at low Reynolds number (Rec,Dh = 10000) and high blowing ratios (M = 1.0). The effect becomes significantly smaller when the Reynolds number is increased. This is mainly attributed to the strongly increasing channel mass flow which equals to a decreasing suction ratio SR = uh/uc of the holes. The experimental results are compared to comprehensive numerical simulations.

Experimental investigations of pressure loss and heat transfer in a 180° bend of a ribbed two-pass internal cooling channel with engine-similar cross-sections

2009 ◽  
Vol 223 (6) ◽  
pp. 709-719 ◽  
Author(s):  
M Schüler ◽  
S O Neumann ◽  
B Weigand
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Cross Sections ◽  
Pressure Loss ◽  
Leading Edge ◽  
Experimental Investigations ◽  
Strong Increase ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Transfer Enhancement

In the present study, the pressure loss and heat transfer of a two-pass internal cooling channel with engine-similar cross-sections were investigated experimentally. This channel consisted of a trapezoidal leading edge pass, a sharp 180° bend, and a nearly rectangular outlet pass. The investigations focused on the influence of tip-to-web distance and rib configuration on pressure loss and heat transfer. The channel was equipped with skewed ribs (α=45°, P/ e=10, e/ dh=0.1) in an inline and a staggered configuration. The dimensionless tip-to-web distance Wel/ dS was varied from 0.6 to 1.2. The investigated Reynolds number ranged from 15 000 up to 100 000. The experimental results showed a strong increase in pressure loss with decreasing tip-to-web distance, while heat transfer was only slightly increasing. Both rib configurations showed nearly the same heat transfer enhancement in the bend region.

Time Resolved Flow Field Investigations of Low Reynolds number Transient Maneuvers

2016 ◽  
Author(s):  
Hauke Ehlers ◽  
Robert Konrath ◽  
Marcel Börner ◽  
Ralf Wokoeck ◽  
Rolf Radespiel
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Low Reynolds Number ◽  
Time Resolved ◽  
Field Investigations ◽  
Low Reynolds

scholarly journals Hydrodynamics of Regular Breaking Wave

2020 ◽  
Author(s):  
Diana De Padova ◽  
Michele Mossa
Keyword(s):  
Flow Field ◽  
Surf Zone ◽  
Laser Doppler Anemometry ◽  
Single Point ◽  
Measurement Techniques ◽  
Experimental Studies ◽  
Outer Region ◽  
Breaking Wave ◽  
Measured Velocity ◽  
Spatial Gradients

Turbulence and undertow currents play an important role in surf-zone mixing and transport processes; therefore, their study is fundamental for the understanding of nearshore dynamics and the related planning and management of coastal engineering activities. Pioneering studies qualitatively described the features of breakers in the outer region of the surf zone. More detailed information on the velocity field under spilling and plunging breakers can be found in experimental works, where single-point measurement techniques, such as Hot Wire Anemometry and Laser Doppler Anemometry (LDA), were used to provide maps of the flow field in a time-averaged or ensemble-averaged sense. Moreover, the advent of non-intrusive measuring techniques, such as Particle Image Velocimetry (PIV) provided accurate and detailed instantaneous spatial maps of the flow field. However, by correlating spatial gradients of the measured velocity components, the instantaneous vorticity maps could be deduced. Moreover, the difficulties of measuring velocity due to the existence of air bubbles entrained by the plunging jet have hindered many experimental studies on wave breaking encouraging the development of numerical model as useful tool to assisting in the interpretation and even the discovery of new phenomena. Therefore, the development of an WCSPH method using the RANS equations coupled with a two-equation k–ε model for turbulent stresses has been employed to study of the turbulence and vorticity distributions in in the breaking region observing that these two aspects greatly influence many coastal processes, such as undertow currents, sediment transport and action on maritime structures.

scholarly journals Effects of Rotation at Different Channel Orientations on the Flow Field inside a Trailing Edge Internal Cooling Channel

2013 ◽  
Vol 2013 ◽  
pp. 1-19 ◽  
Author(s):  
Matteo Pascotto ◽  
Alessandro Armellini ◽  
Luca Casarsa ◽  
Claudio Mucignat ◽  
Pietro Giannattasio
Keyword(s):  
Flow Field ◽  
Working Conditions ◽  
Turbine Blades ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Trailing Edge ◽  
Gas Turbine Blades ◽  
Sst Turbulence Model ◽  
Channel Orientation ◽  
Effects Of Rotation

The flow field inside a cooling channel for the trailing edge of gas turbine blades has been numerically investigated with the aim to highlight the effects of channel rotation and orientation. A commercial 3D RANS solver including a SST turbulence model has been used to compute the isothermal steady air flow inside both static and rotating passages. Simulations were performed at a Reynolds number equal to 20000, a rotation number (Ro) of 0, 0.23, and 0.46, and channel orientations ofγ=0∘, 22.5°, and 45°, extending previous results towards new engine-like working conditions. The numerical results have been carefully validated against experimental data obtained by the same authors for conditionsγ=0∘and Ro = 0, 0.23. Rotation effects are shown to alter significantly the flow field inside both inlet and trailing edge regions. These effects are attenuated by an increase of the channel orientation fromγ=0∘to 45°.

scholarly journals Effect of Reynolds Number and Property Variation on Fluid Flow and Heat Transfer in the Entrance Region of a Turbine Blade Internal-Cooling Channel

2005 ◽  
Vol 2005 (1) ◽  
pp. 36-44 ◽  
Author(s):  
R. Ben-Mansour ◽  
L. Al-Hadhrami
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Mass Flow Rate ◽  
Heat Transfer Rate ◽  
Turbine Blade ◽  
Flow Rate ◽  
Transfer Rate ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Flow And Heat Transfer

Internal cooling is one of the effective techniques to cool turbine blades from inside. This internal cooling is achieved by pumping a relatively cold fluid through the internal-cooling channels. These channels are fed through short channels placed at the root of the turbine blade, usually called entrance region channels. The entrance region at the root of the turbine blade usually has a different geometry than the internal-cooling channel of the blade. This study investigates numerically the fluid flow and heat transfer in one-pass smooth isothermally heated channel using the RNGk−εmodel. The effect of Reynolds number on the flow and heat transfer characteristics has been studied for two mass flow rate ratios (1/1and1/2) for the same cooling channel. The Reynolds number was varied between10 000and50 000. The study has shown that the cooling channel goes through hydrodynamic and thermal development which necessitates a detailed flow and heat transfer study to evaluate the pressure drop and heat transfer rates. For the case of unbalanced mass flow rate ratio, a maximum difference of8.9% in the heat transfer rate between the top and bottom surfaces occurs atRe=10 000while the total heat transfer rate from both surfaces is the same for the balanced mass flow rate case. The effect of temperature-dependent property variation showed a small change in the heat transfer rates when all properties were allowed to vary with temperature. However, individual effects can be significant such as the effect of density variation, which resulted in as much as9.6% reduction in the heat transfer rate.

Computational and experimental investigations in a cyclone dust separator

1997 ◽  
Vol 211 (4) ◽  
pp. 247-257 ◽  
Author(s):  
S M Fraser ◽  
A M Abdel-Razek ◽  
M Z Abdullah
Keyword(s):  
Flow Field ◽  
Richardson Number ◽  
Swirling Flow ◽  
Laser Doppler Anemometry ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Cyclone Chamber ◽  
Dust Separator

Three-dimensional turbulent flow in a model cyclone has been simulated using PHOENICS code and experimental studies carried out using a laser Doppler anemometry (LDA) system. The experimental results were used to validate the computed velocity distributions based on the standard and a modified k-∊ model. The standard k-∊ model was found to be unsatisfactory for the prediction of the flow field inside the cyclone chamber. By considering the strong swirling flow and the streamlined curvature, a k-∊ model, modified to take account of the Richardson number, provided better velocity distributions and better agreement with the experimental results.

Investigation of the Cooling and Underbody Flow Field on a Detailed Scale Model Passenger Car: Part 2—Effect of Ground Simulation

2009 ◽  
Author(s):  
Christoffer Landstro¨m ◽  
Lasse Christoffersen ◽  
Lennart Lo¨fdahl
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Aerodynamic Drag ◽  
Scale Model ◽  
Experimental Investigations ◽  
Passenger Cars ◽  
Local Flow ◽  
Passenger Car ◽  
Reynolds Number Effects ◽  
Cooling Air

Future demands on passenger cars consist to a large extend of making them more energy efficient. Reducing the driving resistance by reducing the aerodynamic drag will be one important part in reducing fuel consumption. In most cases during passenger car development, early experimental investigations are performed in scale model wind tunnels. Considering that such models inevitably suffer from Reynolds number effects it is important to understand how this affects the test results. Investigations of the aerodynamics of a detailed scale model Volvo S60 have been performed in the aerodynamic wind tunnel at Chalmers University of Technology. The investigation aimed at increasing the understanding of how the flow field in scale model testing is affected by ground simulation and different cooling air flow configurations at different Reynolds numbers. A full width moving ground system was used in the experiments. Pressure taps were distributed between the cooling air inlets, the underbody and the vehicle base. An internal six component balance was used to measure global forces and moments. By combining the results from the measurements it was possible to increase the understanding of some of the local flow features. Results showed significant Reynolds number effects both with stationary ground as well as moving ground and rotating wheels. Global aerodynamic drag as well as front and rear axle lift was found to be affected.

Effects of Jetting Orifice Geometry Parameters and Channel Reynolds Number on Bended Channel Cooling for a Novel Internal Cooling Structure

2019 ◽  
Author(s):  
Wei He ◽  
Qinghua Deng ◽  
Juan He ◽  
Tieyu Gao ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Film Cooling ◽  
Leading Edge ◽  
Jet Impingement ◽  
Suction Side ◽  
Outer Wall ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
Blade Leading Edge

Abstract A novel internal cooling structure has been raised recently to enhance internal cooling effectiveness and reduce coolant requirement without using film cooling. This study mainly focuses on verifying the actual cooling performance of the structure and investigating the heat transfer mechanism of the leading edge part of the structure, named bended channel cooling. The cooling performances of the first stage of GE-E3 turbine with three different blade leading edge cooling structures (impingement cooling, swirl cooling and bended channel cooling) were simulated using the conjugate heat transfer method. Furthermore, the effects of jetting orifice geometry and channel Reynolds number were studied with simplified models to illustrate the flow and heat transfer characteristics of the bended channel cooling. The results show that the novel internal cooling structure has obvious advantages on the blade leading edge and suction side under operating condition. The vortex core structure in the bended channel depends on orifice width, but not channel Reynolds number. With the ratio of orifice width to outer wall thickness smaller than a critical value of 0.5, the coolant flows along the external surface of the channel in the pattern of “inner film cooling”, which is pushed by centrifugal force and minimizes the mixing with spent cooling air. Namely, the greatly organized coolant flow generates higher cooling effectiveness and lower coolant demand. Both the Nusselt number on the channel surfaces and total pressure loss increase significantly when the orifice width falls or channel Reynolds increases, but the wall jet impingement distance appears to be less influential.

Effects of Rotation and Channel Orientation on the Flow Field Inside a Trailing Edge Internal Cooling Channel

2012 ◽  
Author(s):  
Matteo Pascotto ◽  
Alessandro Armellini ◽  
Luca Casarsa ◽  
Pietro Giannattasio ◽  
Claudio Mucignat
Keyword(s):  
Flow Field ◽  
Rotation Axis ◽  
Turbine Blades ◽  
Channel Height ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Trailing Edge ◽  
Channel Orientation ◽  
Static Channel ◽  
Inlet Duct

The flow field inside a trailing edge (TE) cooling channel for gas turbine blades has been numerically investigated with reference to the effects of channel rotation and orientation. The channel consists of a single passage with high aspect ratio cross-section. The flow entering from the hub is discharged through both the channel tip and inter-pedestal passages at the TE. A commercial 3D RANS solver including a κ–ω SST turbulence model has been used to simulate the isothermal steady airflow at 20000 Reynolds number in the case of static channel and for two rotation numbers (Ro = 0.23, 0.46) at varying the channel orientation with respect to the rotation axis (γ = 0°, γ = 22.5°, γ = 45°). The present work extends a previous experimental analysis performed by the authors on the same channel geometry, the results of which are used to validate the numerical model. Rotation effects are shown to alter significantly the distribution of both the mass flow in the inlet duct and the velocity along the channel height. This causes remarkable modifications of the 3D flow structures in the inter-pedestal passages and, in particular, the disappearance of the horseshoe vortices from the pedestal upstream face. Changing the channel orientation results in an attenuation of the rotation effects in the inlet duct and in the hub region of the TE.

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