Hydrodynamic Measurements of Jets in Crossflow for Gas Turbine Film Cooling Applications

1989 ◽  
Vol 111 (2) ◽  
pp. 139-145 ◽  
Author(s):  
J. R. Pietrzyk ◽  
D. G. Bogard ◽  
M. E. Crawford
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Laser Doppler Anemometry ◽  
Vertical Plane ◽  
Separation Region ◽  
Mean Velocity ◽  
Stress Components ◽  
Entire Flow ◽  
Hydrodynamic Study ◽  
Field Approaches

This paper presents the results of a detailed hydrodynamic study of a row of inclined jets issuing into a crossflow. Laser-Doppler anemometry was used to measure the vertical and streamwise components of velocity for three jet-to-mainstream velocity ratios: 0.25, 0.5, and 1.0. Mean velocity components and turbulent Reynolds normal and shear stress components were measured at locations in a vertical plane along the centerline of the jet from 1 diameter upstream to 30 diameters downstream of the jet. The results, which have application to film cooling, give a quantitative picture of the entire flow field, from the approaching flow upstream of the jet, through the interaction region of the jet and mainstream, to the relaxation region downstream where the flow field approaches that of a standard turbulent boundary layer. The data indicate the existence of a separation region in the hole from which the jet issues, causing high levels of turbulence and a relatively uniform mean velocity profile at the jet exit.

Effects of Density Ratio on the Hydrodynamics of Film Cooling

1989 ◽  
Author(s):  
J. R. Pietrzyk ◽  
D. G. Bogard ◽  
M. E. Crawford
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Laser Doppler Anemometry ◽  
Density Ratio ◽  
Vertical Plane ◽  
Flux Ratio ◽  
Mean Velocity ◽  
Entire Flow ◽  
Hydrodynamic Study ◽  
Field Approaches

This paper presents the results of a detailed hydrodynamic study of a row of inclined jets issuing into a crossflow with a density ratio of injectant to freestream of two. Laser Doppler anemometry was used to measure the vertical and streamwise components of velocity for a jet-to-freestream mass flux ratio of 0.5. Mean velocity components and turbulent Reynolds normal and shear stress components were measured at locations in a vertical plane along the centerline of the jet from 1 diameter upstream to 30 diameters downstream of the jet. The results, which have application to film cooling, give a quantitative picture of the entire flow field, from the approaching flow upstream of the jet, through the interaction region of the jet and freestream, to the relaxation region downstream where the flow field approaches that of a standard turbulent boundary layer.

Effects of Density Ratio on the Hydrodynamics of Film Cooling

1990 ◽  
Vol 112 (3) ◽  
pp. 437-443 ◽  
Author(s):  
J. R. Pietrzyk ◽  
D. G. Bogard ◽  
M. E. Crawford
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Free Stream ◽  
Laser Doppler Anemometry ◽  
Density Ratio ◽  
Vertical Plane ◽  
Flux Ratio ◽  
Mean Velocity ◽  
Entire Flow ◽  
Hydrodynamic Study

This paper presents the results of a detailed hydrodynamic study of a row of inclined jets issuing into a crossflow with a density ratio of injectant to free stream of 2. Laser-Doppler anemometry was used to measure the vertical and streamwise components of velocity for a jet-to-free stream mass flux ratio of 0.5. Mean velocity components and turbulent Reynolds normal and shear stress components were measured at locations in a vertical plane along the centerline of the jet from 1 diameter upstream to 30 diameters downstream of the jet. The results, which have application to film cooling, give a quantitative picture of the entire flow field, from the approaching flow upstream of the jet, through the interaction region of the jet and free stream, to the relaxation region downstream where the flow field approaches that of a standard turbulent boundary layer.

Experimental and Numerical Investigation of a Cold Turbulent Jet Impinging on a Hot Plate

2012 ◽  
Author(s):  
D. I. Maldonado ◽  
J. K. Abrantes ◽  
L. F. A. Azevedo ◽  
A. O. Nieckele
Keyword(s):  
Flow Field ◽  
Laser Doppler Anemometry ◽  
Turbulence Models ◽  
Impinging Jets ◽  
Reynolds Stresses ◽  
Hot Plate ◽  
Mean Velocity ◽  
Velocity Statistics ◽  
Reliable Assessment ◽  
Anisotropic Structures

Impinging jets are an efficient mechanism to enhance wall heat transfer, and are widely used in engineering applications. The flow field of an impinging jet is quite complex and it is a challenging case for turbulence models validation as well as measurements techniques. In the present work, a detailed investigation of a cold jet impinging on a hot plate operating in the turbulent flow regime was conducted. The flow field was characterized by both Laser Doppler Anemometry and Particle Image Velocimetry (PIV) techniques in order to collect 1st and 2nd order velocity statistics to allow a reliable assessment of the numerical simulations. Comparison was performed with two turbulence methodologies: RANS (κ–ω SST model) and LES (Dynamic Smagorinsky model). The comparison was performed to assess LES feasibility and accuracy in capturing the anisotropic structures that several tested RANS models missed. The mean velocity, instantaneous velocity, Reynolds stresses and Nusselt profiles obtained numerically are compared with experimental data. A physical insight about the general flow dynamics was obtained with the extensive amount of information available from the LES.

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.

scholarly journals Numerical Prediction of Wakes in Cascades and Compressor Rotors Including the Effects of Mixing: Part II — Rotor Passage Flow and Wakes Including the Effects of Spanwise Mixing

1991 ◽  
Author(s):  
N. Suryavamshi ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Axial Flow ◽  
Radial Component ◽  
Navier Stokes ◽  
Mean Velocity ◽  
Compressor Rotor ◽  
Entire Flow ◽  
High Reynolds ◽  
Flow Compressor

The results of a numerical investigation to predict the flow field including wakes and mixing in axial flow compressor rotors has been presented in this paper. The wake behaviour in a moderately loaded compressor rotor has been studied numerically using a three-dimensional incompressible Navier-Stokes solver with a high Reynolds number form of the k–ε turbulence model. The equations are solved using a time dependent implicit technique. The agreement between the measured data and the predictions are good; including the blade boundary layer profiles, wake mean velocity profiles and decay. The ability of the pseudo-compressibility scheme to predict the entire flow field including the near and far wake profiles and its decay characteristics, effect of loading and the viscous losses of a three-dimensional rotor flow field has been demonstrated. An analysis of the passage averaged velocities and the pressure coefficients shows that the mixing in the downstream regions away from the hub and annulus walls is dominated by wake diffusion. In regions away from the walls, the radial mixing is predominantly caused by the transport of mass, momentum and energy by the radial component of velocity in the wake.

Turbulent Flow in a Rotating Two Pass Smooth Channel

1999 ◽  
Vol 121 (4) ◽  
pp. 725-734 ◽  
Author(s):  
Shou-Shing Hsieh ◽  
Ping-Ju Chen ◽  
Hsiang-Jung Chin
Keyword(s):  
Flow Field ◽  
Cross Section ◽  
Flow Separation ◽  
Laser Doppler Anemometry ◽  
Centrifugal Forces ◽  
Mean Velocity ◽  
Axis Of Rotation ◽  
Smooth Channel ◽  
Measured Flow ◽  
Turbulent Air Flow

Laser-Doppler anemometry has been applied to approximately 2-D turbulent air flow in a rotating 2 pass channel of square cross section. The axis of rotation is normal to the axis of the duct, and the flow is radially outward/inward. The duct is of finite length and the walls are isothermal. Smooth channels are experimentally conducted with rotational speeds of 100, 200, and 300 rpm with ReH = 5000 and 10,000. The main features of the flow, flow separation and mean velocity as well as turbulent intensity at particular location along the downstream are presented. The measured flow field is found to be quite complex, consisting of secondary cross-stream and radially outward flows due to the Coriolis effects and centrifugal forces.

Numerical Prediction of Wakes in Cascades and Compressor Rotors Including the Effects of Mixing: Part II—Rotor Passage Flow and Wakes Including the Effects of Spanwise Mixing

1992 ◽  
Vol 114 (3) ◽  
pp. 617-626 ◽  
Author(s):  
N. Suryavamshi ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Axial Flow ◽  
Radial Component ◽  
Navier Stokes ◽  
Mean Velocity ◽  
Compressor Rotor ◽  
Entire Flow ◽  
High Reynolds ◽  
Flow Compressor

The results of a numerical investigation to predict the flow field including wakes and mixing in axial flow compressor rotors has been presented in this paper. The wake behavior in a moderately loaded compressor rotor has been studied numerically using a three-dimensional incompressible Navier–Stokes solver with a high Reynolds number form of the k–ε turbulence model. The equations are solved using a time-dependent implicit technique. The agreement between the measured data and the predictions is good, including the blade boundary layer profiles, wake mean velocity profiles, and decay. The ability of the pseudocompressibility scheme to predict the entire flow field including the near and far wake profiles and its decay characteristics, effect of loading, and the viscous losses of a three-dimensional rotor flow field has been demonstrated. An analysis of the passage-averaged velocities and the pressure coefficients shows that the mixing in the downstream regions away from the hub and annulus walls is dominated by wake diffusion. In regions away from the walls, the radial mixing is predominantly caused by the transport of mass, momentum, and energy by the radial component of velocity in the wake.

Jets in a Crossflow: Effects of Geometry and Blowing Ratio

1999 ◽  
Vol 121 (2) ◽  
pp. 373-378 ◽  
Author(s):  
M. J. Findlay ◽  
M. Salcudean ◽  
I. S. Gartshore
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Film Cooling ◽  
Density Ratio ◽  
Mean Velocity ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Flow Field Characteristics ◽  
Square Jets ◽  
Inlet Conditions

The flow field characteristics of three different geometries of square jets in a crossflow at various blowing ratios are examined. The geometries considered are: perpendicular, streamwise-inclined, and spanwise-inclined jets. The inclined jets are at a 30 deg angle to the wind tunnel floor. Mean velocity and turbulence measurements along with film cooling effectiveness and scalar transport data were obtained. Jet-to-crossflow blowing ratios of 1.5, 1.0 and 0.5 are used with a density ratio of 1. It is shown that the flow field at the jet exit is strongly influenced by the crossflow as well as by the inlet conditions at the entrance to the jet orifice. The strong streamline curvature which is present in the perpendicular and spanwise injection cases appears to result in the greatest turbulence anisotropy. The film cooling effectiveness is best at the lowest blowing ratios as the jet is deflected strongly towards the floor of the wind tunnel, although the improvement is more significant for the streamwise injection case.

Spatiotemporal Characterization of a Conical Swirler Flow Field Under Strong Forcing

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
A. Lacarelle ◽  
T. Faustmann ◽  
D. Greenblatt ◽  
C. O. Paschereit ◽  
O. Lehmann ◽  
...  
Keyword(s):  
Flow Field ◽  
Swirling Flow ◽  
Flow Instability ◽  
Laser Doppler Anemometry ◽  
Helical Structure ◽  
Mean Velocity ◽  
Flow Measurements ◽  
Natural Flow ◽  
Flow Frequency

In this study, a spatiotemporal characterization of forced and unforced flows of a conical swirler is performed based on particle image velocimetry (PIV) and laser Doppler anemometry (LDA). The measurements are performed at a Reynolds number of 33,000 and a swirl number of 0.71. Axisymmetric forcing is applied to approximate the effects of thermoacoustic instabilities on the flow field at the burner inlet and outlet. The actuation frequencies are set at the natural flow frequency (Strouhal number Stf≈0.92) and two higher frequencies (Stf≈1.3 and 1.55) that are not harmonically related to the natural frequency. Phase-averaged measurement are used as a first step to visualize the coherent flow structures. Second, proper orthogonal decomposition (POD) is applied to the PIV data to characterize the effect of the actuation on the fluctuating flow. Measurements indicate a typical natural flow instability of helical nature in the unforced case. The associated induced pressure and flow oscillations travel upstream to the swirler inlet where generally fuel is injected. This observation is of critical importance with respect to the stability of the combustion. Harmonic actuation at different frequencies and amplitudes does not affect the mean velocity profile at the outlet, while the coherent velocity fluctuations are strongly influenced at both the inlet and outlet. On one hand, the dominant helical mode is replaced by an axisymmetric vortex ring if the flow is forced at the natural flow frequency. On the other hand, the natural flow frequency prevails at the outlet under forcing at higher frequencies and POD analysis indicates that the helical structure is still present. The presented results give new insight into the flow dynamics of a swirling flow burner under strong forcing.

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.

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