Performance Prediction of a Converging Slot-Hole Film-Cooling Geometry

2003 ◽  
Author(s):  
J. E. Sargison ◽  
S. M. Guo ◽  
M. L. G. Oldfield ◽  
G. D. Lock ◽  
A. J. Rawlinson
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Performance Prediction ◽  
Film Cooling ◽  
Guide Vane ◽  
Two Dimensional ◽  
Low Speed ◽  
Adiabatic Effectiveness ◽  
Prediction Techniques

Performance prediction techniques have been investigated for use as design tools for the novel console, or converging slothole, film cooling geometry. The performance of the console has been the subject of earlier publications that have demonstrated that this new film cooling hole improves both the heat transfer and aerodynamic performance of turbine vane and rotor blade cooling systems. Three prediction techniques are used and compared in this paper: theoretical models, correlations of experimental data, and two-dimensional Computational Fluid Dynamics. Published experimental measurements of adiabatic effectiveness for the console, and other typical cooling holes at low speed conditions and coolant to mainstream momentum flux ratios of 0.5, 1.1 and 1.5 were used in this analysis. The console results were compared with theoretical predictions of adiabatic effectiveness using a slot model, which was found to be an adequate approximation. Experimental performance data measured in a simple, low-speed apparatus was correlated and used to predict the performance of multiple rows of consoles in a nozzle guide vane at engine representative conditions. This was compared with published experimental data for engine representative conditions and it was found that the correlated low-speed data provided an adequate and simple prediction of the performance of the console in an engine representative film cooling design. Two-dimensional Computational Fluid Dynamics is another relatively rapid prediction tool that was used to predict low speed results.

Computational Fluid Dynamics Techniques for Flows in Lapple Cyclone Separator

2005 ◽  
Vol 498-499 ◽  
pp. 179-185
Author(s):  
A.F. Lacerda ◽  
Luiz Gustavo Martins Vieira ◽  
A.M. Nascimento ◽  
S.D. Nascimento ◽  
João Jorge Ribeiro Damasceno ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Turbulent Flow ◽  
Reynolds Stress ◽  
Cyclone Separator ◽  
Two Dimensional ◽  
Stress Components ◽  
Computational Fluid Dynamics Cfd

A two-dimensional fluidynamics model for turbulent flow of gas in cyclones is used to evaluate the importance of the anisotropic of the Reynolds stress components. This study presents consisted in to simulate through computational fluid dynamics (CFD) package the operation of the Lapple cyclone. Yields of velocity obtained starting from a model anisotropic of the Reynolds stress are compared with experimental data of the literature, as form of validating the results obtained through the use of the Computational fluid dynamics (Fluent). The experimental data of the axial and swirl velocities validate numeric results obtained by the model.

Assessment of Loss Correlations for Performance Prediction of Low Reaction Gas Turbine Stages

2008 ◽  
Author(s):  
Ernesto Benini ◽  
Giovanni Boscolo ◽  
Andrea Garavello
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Gas Turbine ◽  
Performance Prediction ◽  
Reasonable Accuracy ◽  
Algebraic Models ◽  
Two Stage ◽  
Accurate Model ◽  
Multi Stage

In spite of the remarkable advances in the field of the Computational Fluid Dynamics, algebraic models built upon empirical loss and deviation correlations are still one of the most reliable and effective tools to predict the performance of gas turbine stages with reasonable accuracy, especially when low-reaction, multi-stage architectures are considered. This paper deals with a comparison among some of the most popular loss correlations used by gas turbine manufacturers; such comparison is performed on a two-stage low-reaction turbine for which detailed experimental data are available. An overall assessment on the validity of loss correlations is carried out to help the designer/analyst using the most accurate model when both on- and off-design are to be carried out.

Research on Computational Fluid Dynamics with Effect of Grid Quality on the Accuracy of Simulated Results of Two Dimensional Low-Speed Parallel Flow

2014 ◽  
Vol 685 ◽  
pp. 232-235
Author(s):  
Ning Kang ◽  
Yuan Cao
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Direction ◽  
Grid Generation ◽  
Domain Size ◽  
Parallel Flow ◽  
Computational Error ◽  
Two Dimensional ◽  
Low Speed ◽  
Generation Costs

In the field of computational fluid dynamics, grid generation costs most of work. The accuracy and reliability of the simulated results depend directly on grid quality. The two dimensional parallel flow with low speed was used to study the effect of grid quality on simulated results. Several conclusions are obtained. The computational error decreases with the increase of domain size in flow direction. Too many grids in flow direction will lead to bigger round-off error, while too few grids will make it harder to catch the correct flow. The increase of grid quantity in the direction perpendicular to flow direction will decrease the computational error, but the effect is not obvious. Increasing the grid quantity in the area near the wall will decrease the computational error.

Experimental and numerical analysis of the unsteady influence of the inlet guide vanes on cavitation performance of an axial pump

2018 ◽  
Vol 233 (11) ◽  
pp. 3816-3826 ◽  
Author(s):  
Zhiwei Guo ◽  
Jingye Pan ◽  
Zhongdong Qian ◽  
Bin Ji
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Guide Vane ◽  
Inlet Guide Vane ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Cavitation Performance ◽  
Axial Pump ◽  
Simulation Results

The effect of the inlet guide vanes on cavitation performance of an axial pump is investigated to assess the mechanism for cavitation in pumps and improve their cavitation performance. The effect of inlet guide vane angles on cavitation performance was assessed experimentally, and computational fluid dynamics was used to analyze the inner flow field of the axial pump and to probe the cavitation mechanism. The simulation results agree qualitatively with the experimental data, showing that cavitation performance is improved with positive inlet guide vane angles but hampered with negative ones. The cavitation performance itself is controlled by the cavitation volume, which first expands circumferentially when the net positive suction head decreases from a certain large value and then develops toward the axis radially after the net positive suction head reaches a certain value. This is when the cavitation performance deteriorates. Comparing cavitation volume for the critical net positive suction head as determined by two different methods, the method based on efficiency drop (NPSHeff.,1%) is found to be more suitable than that based on head drop (NPSHhead.,3%). Furthermore, the distribution of swirl is shown to be closely related to the distribution of cavitation, a feature that may be used to predict cavitation along the impeller.

Accuracy of Centrifugal Compressor Stages Performance Prediction by Means of High Fidelity CFD and Validation Using Advanced Aerodynamic Probe

2013 ◽  
Author(s):  
V. V. N. K. Satish K. ◽  
Emanuele Guidotti ◽  
Dante Tommaso Rubino ◽  
Libero Tapinassi ◽  
Sridhar Prasad
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Centrifugal Compressor ◽  
Performance Prediction ◽  
Numerical Models ◽  
Cavity Flow ◽  
Pressure Probe ◽  
High Fidelity ◽  
Leakage Flows

During the design of modern high efficiency, wide operating range centrifugal compressor stages, Computational Fluid Dynamics (CFD) plays an increasing role in the assessment of the performance prediction. Nevertheless experimental data are valuable and necessary to assess the performance of the stages and to better understand the flow features in detail. A big effort is currently being made to increase the fidelity of the numerical models and the probe measurement accuracy during both the design and validation phases of centrifugal compressor stages. This study presents the flow analysis of centrifugal compressor stages using high fidelity computational fluid dynamics with a particular attention to the cavity flow modeling and comparison with experimental data, using an advanced fast response aerodynamic pressure probe. Different flow coefficient centrifugal compressor stages were used for the validation of the numerical models with a particular attention to the effects of cavity flow on the flow phenomena. The computational domain faithfully reproduced the geometry of the stages including secondary flow cavities. The availability of a new in-house automated tool for cavity meshing allowed to accurately resolve leakage flows with a reasonable increase in computational and user time. Time averaged data from CFD analysis were compared with advanced experimental ones coming from the unsteady pressure probe, for both overall performance and detailed two-dimensional maps of the main flow quantities at design and off design conditions. It was found that the increase in computational accuracy with the complete geometry modeling including leakage flows was substantial and the results of the computational model were in good agreement with the experimental data. Moreover the combination of both advanced computational and experimental techniques enabled deeper insights in the flow field features. The comparison showed that only with advanced high fidelity CFD including leakage flows modeling did the numerical predictions meet the requirements for efficiency, head and operating margin, otherwise not achievable with simplified models (CFD without cavities).

The Application of Non-Axisymmetric Endwall Contouring in a Single Stage, Rotating Turbine

2009 ◽  
Author(s):  
Glen Snedden ◽  
Dwain Dunn ◽  
Grant Ingram ◽  
David Gregory-Smith
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Gradient ◽  
Full Scale ◽  
Secondary Flows ◽  
Tip Clearance ◽  
Detailed Understanding ◽  
Low Speed ◽  
Endwall Contouring ◽  
Probe Measurements

As turbine manufacturers strive to develop machines that are more efficient, one area of focus has been the control of secondary flows. To a large extent these methods have been developed through the use of computational fluid dynamics and detailed measurements in linear and annular cascades and proven in full scale engine tests. This study utilises 5-hole probe measurements in a low speed, model turbine in conjunction with computational fluid dynamics to gain a more detailed understanding of the influence of a generic endwall design on the structure of secondary flows within the rotor. This work is aimed at understanding the influence of such endwalls on the structure of secondary flows in the presence of inlet skew, unsteadiness and rotational forces. Results indicate a 0.4% improvement in rotor efficiency as a result of the application of the generic non-axisymmetric endwall contouring. CFD results indicate a clear weakening of the cross passage pressure gradient, but there are also indications that custom endwalls could further improve the gains. Evidence of the influence of endwall contouring on tip clearance flows is also presented.

Comparison of RANS and DES Modeling Against Measurements of Leading Edge Film Cooling on a First-Stage Vane

2016 ◽  
Author(s):  
S. Ravelli ◽  
G. Barigozzi
Keyword(s):  
Film Cooling ◽  
Guide Vane ◽  
Leading Edge ◽  
Spanwise Direction ◽  
Intensity Level ◽  
Edge Region ◽  
Cooling Effectiveness ◽  
Stagnation Line ◽  
Film Cooling Effectiveness ◽  
Adiabatic Effectiveness

The performance of a showerhead arrangement of film cooling in the leading edge region of a first stage nozzle guide vane was experimentally and numerically evaluated. A six-vane linear cascade was tested at an isentropic exit Mach number of Ma2s = 0.42, with a high inlet turbulence intensity level of 9%. The showerhead cooling scheme consists of four staggered rows of cylindrical holes evenly distributed around the stagnation line, angled at 45° towards the tip. The blowing ratios tested are BR = 2.0, 3.0 and 4.0. Adiabatic film cooling effectiveness distributions on the vane surface around the leading edge region were measured by means of Thermochromic Liquid Crystals technique. Since the experimental contours of adiabatic effectiveness showed that there is no periodicity across the span, the CFD calculations were conducted by simulating the whole vane. Within the RANS framework, the very widely used Realizable k-ε (Rke) and the Shear Stress Transport k-ω (SST) turbulence models were chosen for simulating the effect of the BR on the surface distribution of adiabatic effectiveness. The turbulence model which provided the most accurate steady prediction, i.e. Rke, was selected for running Detached Eddy Simulation at the intermediate value of BR = 3. Fluctuations of the local temperature were computed by DES, due to the vortex structures within the shear layers between the main flow and the coolant jets. Moreover, mixing was enhanced both in the wall-normal and spanwise direction, compared to RANS modeling. DES roughly halved the prediction error of laterally averaged film cooling effectiveness on the suction side of the leading edge. However, neither DES nor RANS provided the expected decay of effectiveness progressing downstream along the pressure side, with 15% overestimation of ηav at s/C =0.2.

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