Experimental Heat Transfer and Boundary Layer Measurements on a Ceramic Matrix Composite Surface

2021 ◽  
Author(s):  
Peter Wilkins ◽  
Stephen Lynch ◽  
Karen A. Thole ◽  
San Quach ◽  
Tyler Vincent
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Matrix Composite ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix ◽  
Composite Surface ◽  
Experimental Heat ◽  
Experimental Heat Transfer

Effect of a Ceramic Matrix Composite Surface on Film Cooling

2021 ◽  
Author(s):  
Peter H. Wilkins ◽  
Stephen P. Lynch ◽  
Karen A. Thole ◽  
San Quach ◽  
Tyler Vincent ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Matrix Composite ◽  
Film Cooling ◽  
Gas Turbines ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix ◽  
Composite Surface ◽  
Minimal Impact ◽  
Cooling Hole ◽  
Adiabatic Effectiveness

Abstract Ceramic matrix composite (CMC) parts create the opportunity for increased turbine entry temperatures within gas turbines. To achieve the highest temperatures possible, film cooling will play an important role in allowing turbine entry temperatures to exceed acceptable surface temperatures for CMC components, just as it does for the current generation of gas turbine components. Film cooling over a CMC surface introduces new challenges including roughness features downstream of the cooling holes and changes to the hole exit due to uneven surface topography. To better understand these impacts, this study presents flowfield and adiabatic effectiveness CFD for a 7-7-7 shaped film cooling hole at two CMC weave orientations. The CMC surface selected is a 5 Harness Satin weave pattern that is examined at two different orientations. To understand the ability of steady RANS to predict flow and convective heat transfer over a CMC surface, the weave surface is initially simulated without film and compared to previous experimental results. The simulation of the weave orientation of 0°, with fewer features projecting into the flow, matches fairly well to the experiment, and demonstrates a minimal impact on film cooling leading to only slightly lower adiabatic effectiveness compared to a smooth surface. However, the simulation of the 90° orientation with a large number of protruding features does not match the experimentally observed surface heat transfer. The additional protruding surface produces degraded film cooling performance at low blowing ratios but is less sensitive to blowing ratio, leading to improved relative performance at higher blowing ratios, particularly in regions far downstream of the hole.

Heat Transfer Analysis of Jet Impingement Cooling on a Simulated Ceramic Matrix Composite Surface

2017 ◽  
Author(s):  
Karthik Krishna ◽  
Mark Ricklick
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Matrix Composite ◽  
Ceramic Matrix Composite ◽  
Jet Impingement ◽  
Ceramic Matrix ◽  
Heat Transfer Analysis ◽  
Test Surface ◽  
Composite Surface ◽  
The Impact

Ceramic Matrix Composite is a woven material characterized by a significant level of surface waviness of 35–60μm and surface roughness of 5–6μm. To be implemented in a future gas turbine engine they will be cooled traditionally to increase power and efficiency. To analyze the CMC surface effects on heat transfer rate, an impinging circular jet on a simulated CMC surface is studied experimentally and the CMC surface is represented by a high resolution CNC machined surface. The test parameters are jet to plate distance of 7 jet diameters, oblique impingement angles of 45° and 90° and Reynolds numbers of 11,000 to 35,000. The test surface is broken down into constant temperature segments, and individual segment Nusselt number is determined and plotted for the various impingement cases studied. Area-Averaged results show negligible changes in average Nusselt number as compared to the hydrodynamically smooth surface. The impact of the CMC surface feature is negligible compared to the uncertainty in heat transfer coefficient, and therefore traditional design tools can be utilized.

Experimental Heat Transfer and Boundary Layer Measurements on a Ceramic Matrix Composite Surface

2020 ◽  
Author(s):  
Peter H. Wilkins ◽  
Stephen P. Lynch ◽  
Karen A. Thole ◽  
San Quach ◽  
Tyler Vincent
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Surface Morphology ◽  
Gas Turbines ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Composite Surface ◽  
Weave Pattern ◽  
The Impact

Abstract Ceramic matrix composites (CMCs) are quickly becoming more prevalent in the design of gas turbines due to their advantageous weight and thermal properties. While there are many advantages, the CMC surface morphology differs from that of conventional cast airfoil components. Despite a great deal of research focused on the material properties of CMCs, little public work has been done to investigate the impact that the CMC surface morphology has on the boundary layer development and resulting heat transfer. In this study, a scaled-up CMC weave pattern was developed and tested in a low speed wind tunnel to evaluate both heat transfer and boundary layer characteristics. Results from these experiments indicate that the CMC weave pattern results in augmented heat transfer and flow field properties that significantly vary locally when compared to a smooth surface.

Experimental Heat Transfer and Boundary Layer Measurements on a Ceramic Matrix Composite Surface

2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Peter H. Wilkins ◽  
Stephen P. Lynch ◽  
Karen A. Thole ◽  
San Quach ◽  
Tyler Vincent
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Surface Morphology ◽  
Gas Turbines ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Composite Surface ◽  
Weave Pattern ◽  
The Impact

Abstract Ceramic matrix composites (CMCs) are quickly becoming more prevalent in the design of gas turbines due to their advantageous weight and thermal properties. While there are many advantages, the CMC surface morphology differs from that of conventional cast airfoil components. Despite a great deal of research focused on the material properties of CMCs, little public work has been done to investigate the impact that the CMC surface morphology has on the boundary layer development and resulting heat transfer. In this study, a scaled-up CMC weave pattern was developed and tested in a low-speed wind tunnel to evaluate both heat transfer and boundary layer characteristics. Results from these experiments indicate that the CMC weave pattern results in augmented heat transfer and flow field properties that significantly vary locally when compared with a smooth surface.

Experimental Heat Transfer Investigation in a Multisplitter LP Vane Architecture

2010 ◽  
Author(s):  
V. Pinilla ◽  
J. P. Solano ◽  
G. Paniagua ◽  
S. Lavagnoli ◽  
T. Yasa
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Pressure Ratio ◽  
Transition To Turbulence ◽  
Time Resolved ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Flow Features ◽  
Aero Engines ◽  
Layered Thin Film

This paper reports the external convective heat transfer in an innovative low pressure vane with multisplitter configuration. Three small aerodynamic blades are positioned between each structural vane, providing a novel architecture for ultra-high by-pass ratio aero-engines, with increased LP vane radius and swan-neck diffuser to link the HP turbine. The measurements have been performed in the compression tube test rig of the von Karman Institute, using single layered thin film gauges. Time-averaged and time-resolved heat transfer distributions are presented for the three aerovanes and for the structural blade, at three pressure ratios tested at representative conditions of modern aeroengines, with M2,is ranging from 0.87 to 1.07 and a Reynolds number of about 106. This facility is specially suited to control the gas-to-wall temperature ratio. Accurate time-averaged heat transfer distributions around the aerovanes are assessed, that allow characterizing the boundary layer status for each position and pressure ratio. The heat transfer distribution around the structural blade is also obtained, depicting clear transition to turbulence, as well as particular flow features on the pressure side, like separation bubbles. Unsteady data analysis reveals the destabilizing effect of the rotor left-running shock on the aerovanes boundary layer, as well as the shift of transition onset for different blade passing events.

Laminar Combined Convection From a Rotating Cone

1963 ◽  
Vol 85 (1) ◽  
pp. 29-34 ◽  
Author(s):  
R. G. Hering ◽  
R. J. Grosh
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Free Convection ◽  
Numerical Solutions ◽  
Temperature Fields ◽  
Boundary Layer Equations ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Cone Apex ◽  
Rotating Cone

The effect of free convection on heat transfer and on the flow field about a rotating cone is studied. A similar solution for the laminar boundary-layer equations is found to exist when the cone surface temperature varies linearly with distance from the cone apex. The transformed boundary-layer equations contain the important parameter Gr/Re2. This parameter determines the relative importance of the free convection motions on forced convection. Numerical solutions of the transformed equations for aiding flows have been carried out for Prandtl number 0.7 and different values of Gr/Re2. Results are reported for the heat transfer, shear stress, shaft moment, and velocity and temperature fields. Criteria are given for subdividing the regimes of flow as purely free, purely forced, and combined flow. Preliminary experimental heat-transfer results are reported which indicate the trends predicted by theory.

scholarly journals The Turbulent Boundary Layer on a Porous Plate: Experimental Heat Transfer with Uniform Blowing and Suction, with Moderately Strong Acceleration

1972 ◽  
Vol 94 (1) ◽  
pp. 111-118 ◽  
Author(s):  
W. H. Thielbahr ◽  
W. M. Kays ◽  
R. J. Moffat
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Porous Plate ◽  
Stanton Number ◽  
Graphical Form ◽  
Temperature Dependent ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Fluid Properties

Experimental data are presented for heat transfer to the turbulent boundary layer subjected to transpiration and acceleration at constant values of the acceleration parameter K = (ν/U∞2)(dU∞/dx) of approximately 1.45 × 10−6. This is a moderately strong acceleration, but not so strong as to result in laminarization of the boundary layer. The results for transpiration fractions F of −0.002, 0.0, and +0.0058 are presented in detail in tabular form, and in graphs of Stanton number versus enthalpy thickness Reynolds number. In addition, temperature profiles at several stations are presented. Stanton number results for F = −0.004, +0.002, and +0.004 are also presented, but in graphical form only. The data were obtained using air as both the free-stream and the transpired fluid, at relatively low velocities, and with temperature differences sufficiently low (approximately 40 deg F) that the influence of temperature-dependent fluid properties is minimal. All data were obtained with the surface maintained at a temperature invariant in the direction of flow.

scholarly journals Heat Transfer to the Highly Accelerated Turbulent Boundary Layer With and Without Mass Addition

1970 ◽  
Vol 92 (3) ◽  
pp. 499-505 ◽  
Author(s):  
W. M. Kays ◽  
R. J. Moffat ◽  
W. H. Thielbahr
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layers ◽  
Stanton Number ◽  
Temperature Profiles ◽  
Transfer Data ◽  
Experimental Heat ◽  
Prediction Scheme ◽  
Experimental Heat Transfer ◽  
Impermeable Wall

Experimental heat transfer data are presented for a series of asymptotic accelerated turbulent boundary layers for the case of an impermeable wall, and several cases of blowing, and suction. The data are presented as Stanton number versus enthalpy thickness Reynolds number. As noted by previous investigators, acceleration causes a depression in Stanton number when the wall is impermeable. Suction increases this effect, while blowing suppresses it. The combination of mild acceleration and strong blowing results in Stanton numbers which lie above the correlation for the same blowing but no acceleration. Velocity and temperature profiles are presented, from which it is possible to deduce explanations for the observed behavior of the Stanton number. A prediction scheme is proposed which is demonstrated to quite adequately reproduce the Stanton number results, using correlations derived from the profiles.

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