Novel Turbine Endwall Contours for the Reduction of Heat Transfer Generated Using the Ice Formation Method

2012 ◽  
Author(s):  
Kristian Haase ◽  
Sven Winkler ◽  
Bernhard Weigand ◽  
Sven Olaf Neumann
Keyword(s):  
Heat Transfer ◽  
Guide Vane ◽  
Three Dimensional ◽  
Vortical Flow ◽  
Ice Formation ◽  
The Novel ◽  
Average Heat ◽  
Low Pressure Turbine ◽  
Transfer Behavior ◽  
Formation Method

Three-dimensional contouring of vane endwalls has proven to be an efficient method for reducing aerodynamic losses or, respectively, endwall heat transfer by active manipulation of the complex vortical flow structures in the vane passage. The present study shows the application of the Ice Formation Method for endwall contouring of a guide vane row with the goal of reducing endwall heat transfer. Endwall contours for the guide vane row of a low pressure turbine are experimentally generated in form of ice contours and evaluated with respect to their heat transfer behavior. A comparison with the flat plate showed that average heat transfer is considerably reduced for the ice-contoured endwalls with reductions up to 42%. The generated endwall contours were also digitized and used in numerical simulations. The latter allowed for a comparison of endwall heat transfer for the novel contours with the heat transfer for a flat, uncontoured endwall. This showed that the new endwall contours also feature decreased average heat transfer compared to the flat endwall with the maximum obtained reduction being 12%.

Turbine Endwall Contouring for the Reduction of Endwall Heat Transfer Using the Ice Formation Method Along With Computational Fluid Dynamics

2014 ◽  
Author(s):  
Sven Winkler ◽  
Kristian Haase ◽  
Janosch Brucker ◽  
Bernhard Weigand
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Ice Formation ◽  
Formation Method ◽  
Endwall Contouring ◽  
Dynamics Simulations

Turbine endwall contouring has become very popular for optimizing gas turbines. Increasingly often, three-dimensional contours are applied between turbine airfoils to reduce aerodynamic losses or heat transfer rates. These reductions directly result from the shaping of such contours which modifies the flow and thermal field in their vicinity. Here, we report on the development of novel endwall contours for a generic low pressure vane profile to reduce endwall heat transfer. Using the flat endwall as baseline, different endwall contours were created using the Ice Formation Method. This natural approach imposes only minimum restrictions on the design space and is therefore considered advantageous to other optimization procedures. The created contours were subsequently analyzed by Computational Fluid Dynamics simulations. Results showed that all created contours reduced endwall heat transfer compared to the baseline, the highest reduction being 7% in terms of the averaged endwall Stanton number. For this endwall contour, we performed detailed analyses of the numerically predicted flow and temperature fields to indicate how the shaping of this contour affects the flow and temperature fields and hence causes the observed heat transfer reduction.

scholarly journals Finite Element Analysis of Natural Thawing Heat Transfer of Artificial Frozen Soil in Shield-Driven Tunnelling

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Yong Fu ◽  
Jun Hu ◽  
Jia Liu ◽  
Shengbin Hu ◽  
Yunhui Yuan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Three Dimensional ◽  
Frozen Soil ◽  
Soil Reinforcement ◽  
Freezing Process ◽  
Element Analysis ◽  
Heat Transfer Behavior ◽  
Transfer Behavior ◽  
Three Dimensional Finite Element

The technology of artificial horizontal freezing method is increasingly being used in the soil reinforcement of urban underground projects such as shield-driven tunnelling. Compared with the freezing process, the thawing process is more complicated, and the thawing behavior of artificial frozen soil surrounding shield-driven tunnels has not been well investigated in both the academic and industrial domains. This study, therefore, aims to investigate the natural thawing heat transfer behavior of artificial horizontal frozen soil in shield-driven tunnelling using a three-dimensional finite element method. The finite element modelling is based on the horizontal freezing reinforcement project of Chating Station to Jiqingmen Station Tunnel in the Nanjing Metro Line 2. Validation between finite element results and site measured results is firstly conducted. The natural thawing temperature field contours as well as the radial and longitudinal distributions of natural thawing temperature in the frozen soil surrounding the tunnel are then explicitly examined. Furthermore, sensitivity analysis of influencing factors such as the thermal conductivity, latent heat of phase change, ambient temperature inside tunnel, freezing time, and original ground temperature is carried out. The results and findings of this study may enrich the current limited database and enable a better understanding of natural thawing heat transfer behavior of artificial frozen soil in shield-driven tunnelling.

Improved Approach to an Endwall Heat Transfer Analysis: A Linear Guide Vane and a Curved Duct

1998 ◽  
Author(s):  
A. Khalatov
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Guide Vane ◽  
Three Dimensional ◽  
Heat Transfer Analysis ◽  
Freestream Velocity ◽  
Linear Guide ◽  
Curved Duct ◽  
Experimental Correlation ◽  
The Common

This paper consists of two sections. The first section of the paper illustrates successful application of the improved approach developed by author to the endwall heat transfer data analysis in a low speed linear guide vane and in a curved duct. Effects of a three dimensional turbulent flow, a horseshoe vortex, a passage vortex, as well as an entry boundary layer thickness have been considered in both passages and as a result the common experimental correlation on a local heat transfer have been derived for the H/t = 1.0 ratio. All affected factors are presented as a superposition of the linear correction functions in the basic experimental correlation for a flat plate heat transfer. In the second section the common correlation is used as the reference correlation to establish effect of the span-to-pitch ratio on the endwall heat transfer in both passages. It was found that variation in the H/t ratio affects slightly the freestream velocity; the most important result which came from the heat transfer study is that in contrast to a curved duct a heat transfer rate in a blade passage is reduced while the H/t ratio decreases. Comparison of the experimental data obtained by the author with results of the two-dimensional heat transfer prediction confirms that it is very important to take a three-dimensional heat transfer nature into account in design of the endwall convective cooling system. It has been demonstrated that distinction between the results of two- and three dimensional approach to the endwall heat transfer can achieve up to 70% at the passage’s inlet area.

Heat Transfer and Turbulent Flow Characteristics of Isolated Three-Dimensional Protrusions in Channels

1991 ◽  
Vol 113 (3) ◽  
pp. 597-603 ◽  
Author(s):  
P. T. Roeller ◽  
J. Stevens ◽  
B. W. Webb
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Channel Wall ◽  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Average Heat ◽  
Flow Acceleration ◽  
Dimensional Flow ◽  
Wall Spacing

The flow structure and average heat transfer characteristics of single, isolated three-dimensional protrusions in a flow channel have been investigated experimentally. This configuration has relevance in the electronics industry. The study was designed to identify the influence of the three-dimensional flow around a heated protrusion on its average heat transfer. Heated protrusions varying in width between 0.12 and 1.0 channel widths for a fixed protrusion height and streamwise length were studied in the channel Reynolds number range 500≤Re≤10,000. The channel wall spacing was also varied parametrically between 1.25 and 2.5 streamwise protrusion lengths. The study included both average heat transfer measurements, and detailed local velocity and turbulent flow structure measurements made using laser-Doppler velocimetry. The experimental results show that the Nusselt number increases with both decreasing channel wall spacing and decreasing protrusion width. The increase in heat transfer with decreasing wall spacing is explained by the accelerated flow due to the protrusion-obstructed channel. Increasing Nusselt number with decreasing protrusion width is a result of increased three-dimensional flow and associated turbulent mixing. Both of these flow-related phenomena are illustrated with local mean velocity and turbulence intensity measurements. The presence of recirculation zones both upstream and downstream of the module is revealed. The flow acceleration around the heated protrusions, and three dimensionality of the flow and heat transfer are competing mechanisms; the higher heat transfer due to flow acceleration around the protrusions for larger protrusions goes counter to the trend for higher heat transfer due to increased three-dimensional flow and transport for smaller protrusions. A Nusselt number correlation is developed as a function of channel Reynolds number and protrusion and channel geometric parameters, which describes the tradeoffs discussed.

Film Cooling Research on the Endwall of a Turbine Nozzle Guide Vane in a Short Duration Annular Cascade: Part 2—Analysis and Correlation of Results

1992 ◽  
Vol 114 (4) ◽  
pp. 741-746 ◽  
Author(s):  
S. P. Harasgama ◽  
C. D. Burton
Keyword(s):  
Heat Transfer ◽  
Pressure Gradient ◽  
Film Cooling ◽  
Guide Vane ◽  
Three Dimensional ◽  
Companion Paper ◽  
Hole Injection ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Annular Cascade

Results have been presented on the heat transfer characteristics of the film cooled endwall (platform) of a turbine nozzle guide vane in an annular cascade at engine representative conditions in a companion paper by Harasgama and Burton (1992). The present paper reports on the analysis of these measurements. The experimental results are well represented by the superposition theory of film cooling. It is shown that high cooling effectiveness can be achieved when the data are corrected for axial pressure gradients. The data are correlated against both the slot-wall jet parameter and the discrete hole injection function for flat-plate, zero pressure gradient cases. The pressure gradient correction brings the present data to within ± 11 percent of the discrete hole correlation. Preliminary predictions of heat transfer reduction have been carried out using the STANCOOL program. These indicate that the code can predict the magnitude of heat transfer reduction correctly, although the absolute values are not in good agreement. This is attributed to the three-dimensional nature of the flow at the endwall.

On the optimization of 3D-flow and heat transfer by using the Ice Formation Method: Vane endwall heat transfer

2015 ◽  
Vol 88 ◽  
pp. 957-964 ◽  
Author(s):  
Sven Winkler ◽  
Kristian Haase ◽  
Rostyslav Lyulinetskyy ◽  
Sven Olaf Neumann ◽  
Bernhard Weigand
Keyword(s):  
Heat Transfer ◽  
Ice Formation ◽  
3D Flow ◽  
Flow And Heat Transfer ◽  
Formation Method

scholarly journals A Numerical Study Of Micro-Jet Impingement Cooling Inside A High Pressure Turbine Vane

2021 ◽  
Author(s):  
Marcel L. De Paz
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Numerical Study ◽  
Three Dimensional ◽  
Leading Edge ◽  
Jet Impingement ◽  
High Pressure Turbine ◽  
Impingement Cooling ◽  
Average Heat ◽  
Heated Area

A thorough numerical analysis of micro-impingement cooling for application in high pressure turbine vanes is presented. The fundamental flow of an axisymmetric jet is first modeled and studied to ascertain the validity of the results. Subsequent, a fully three dimensional curved vane is modeled with an in-line impinging array of jet diamters 0.5mm. The analysis reveals that spent air collects with increasing streamwise distance from the leading edge, thereby increasing jet exit velocities across the array. For all cases studied, an increase in jet to target spacing increased the overall Reynolds number of the array, but decreased the average heat transfer rate. Micro diameters of 0.25mm were subsequently studied for full vane geometry. For a given mass flow per unit of heated area, the micro-jets considerably increased the average heat transfer by 63%. Similar enhancements were obtained at a fixed pressure drop percentage, and for a desired average heat transfer.

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