scholarly journals On- and off-design performance of a model rotating turbine with non-axisymmetric endwall contouring and a comparison to cascade data

2018 ◽  
Vol 122 (1250) ◽  
pp. 646-665 ◽  
Author(s):  
G. Snedden ◽  
D. Dunn ◽  
G. Ingram
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Secondary Flows ◽  
Objective Functions ◽  
Design Studies ◽  
Cascade Testing ◽  
Numerical Predictions ◽  
Blade Row ◽  
Hot Film ◽  
Isentropic Efficiency

ABSTRACTNon-axisymmetric endwalls in turbine stages have shown to be a robust method to improve the performance of turbines in both power generation and aero-derivative applications. Non-axisymmetric endwalls target the control of secondary flows and are designed using detailed computational fluid dynamics coupled with a variety of optimisation algorithms and utilising a number of objective functions according to the engine company or researcher's preference. These numerical predictions are often backed up by detailed measurements in linear and annular cascades and later proven in full-scale engine tests. Relatively little literature is available describing their performance in rotating test rigs or at conditions other than design, apart from that of the authors. This study comprehensively revisits the low-speed, model turbines used in the earlier study, replacing all of the 5-hole probe data with more accurate results and additional hot-film measurements. These results together with computational fluid dynamics solutions are used to show the success of the method across a large incidence range and to compare to earlier cascade results for a similar endwall and blade profile to establish the usefulness of cascade testing in this application. In addition, a comparison to two other off-design studies is made. Results indicate that the endwalls successfully improve the rotor total isentropic efficiency at all test conditions and that the improvement increases with increased turning in the blade row, from 0.5% to 1.8% across the incidence range. The results also compare well to the estimation of isentropic efficiency improvement that can be drawn from the cascade testing which stands at 1.55%.

Development of an automated non-axisymmetric endwall contour design system for the rotor of a 1-stage research turbine – part 1: System design

2019 ◽  
Vol 234 (5) ◽  
pp. 565-581
Author(s):  
Jonathan Bergh ◽  
Glen Snedden ◽  
Daya Reddy
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Global Optimization ◽  
Secondary Flow ◽  
Optimization Procedure ◽  
Secondary Flows ◽  
Design System ◽  
Efficient Global Optimization ◽  
Optimization Approach ◽  
Blade Row

Secondary flows are a well-known source of loss in turbomachinery flows, contributing up to 30% of the total aerodynamic blade row loss. With the increase in pressure on aero-engine manufacturers to produce lighter, more powerful and increasingly more efficient engines, the mitigation of the losses associated with secondary flow has become significantly more important than in the past. This is because the production of secondary flow is closely related to the amount of loading and hence the work output of a blade row, which then allows part counts and overall engine weight to be reduced. Similarly, higher efficiency engines demand larger engine pressure ratios which in turn lead to reduced blade passage heights in which secondary flows then dominate. This article discusses the design and application of an automated turbine non-axisymmetric endwall contour optimization procedure for the rotor of a low speed, 1-stage research turbine, which was used as part of a research program to determine the most effective objective functions for reducing turbine secondary flows. In order to produce as effective as possible designs, the optimization procedure was coupled to a computational fluid dynamics routine with as high a degree of fidelity as possible and an efficient global optimization scheme based on the so-called efficient global optimization algorithm. In order to compliment the requirements of the efficient global optimization approach, as well as offset some of the computational requirements of the computational fluid dynamics, the DACE metamodel was used as an underlying surrogate model.

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.

Metal Temperature Prediction of a Dry Low NOx Class Flame Tube by Computational Fluid Dynamics Conjugate Heat Transfer Approach

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Riccardo Da Soghe ◽  
Cosimo Bianchini ◽  
Antonio Andreini ◽  
Lorenzo Mazzei ◽  
Giovanni Riccio ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Operating Conditions ◽  
Metal Temperature ◽  
Thermal Loads ◽  
Flame Tube ◽  
Numerical Predictions ◽  
Partial Load ◽  
Critical Components

Combustor liner of present gas turbine engines is subjected to high thermal loads as it surrounds high temperature combustion reactants and is hence facing the related radiative load. This generally produces high thermal stress levels on the liner, strongly limiting its life expectations and making it one of the most critical components of the entire engine. The reliable prediction of such thermal loads is hence a crucial aspect to increase the flame tube life span and to ensure safe operations. The present study aims at investigating the aerothermal behavior of a GE Dry Low NOx (DLN1) class flame tube and in particular at evaluating working metal temperatures of the liner in relation to the flow and heat transfer state inside and outside the combustion chamber. Three different operating conditions have been accounted for (i.e., lean–lean partial load, premixed full load, and primary load) to determine the amount of heat transfer from the gas to the liner by means of computational fluid dynamics (CFD). The numerical predictions have been compared to experimental measurements of metal temperature showing a good agreement between CFD and experiments.

Computational Fluid Dynamics Modeling of Gaseous Cavitation in Lubricating Vane Pumps: An Approach Based on Dimensional Analysis

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Umberto Stuppioni ◽  
Alessio Suman ◽  
Michele Pinelli ◽  
Alessandro Blum
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Dimensional Analysis ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Dynamic Features ◽  
Dynamics Modeling ◽  
Vane Pump ◽  
Numerical Predictions ◽  
Pressure Ripple

Abstract This paper addresses the problem of computational fluid dynamics (CFD) modeling of gaseous cavitation (GC) in lubricating positive-displacement pumps (PDPs). It is important for designers and analysts to predict the dynamic features of air release/dissolution processes which characterize this phenomenon, along with their effects on filling capability and noise-vibration-harshness behavior of the machine. The focus is on the empirical tuning of the commercial homogeneous-flow cavitation model known as dissolved gas model (DGM). Considering an automotive case study of a balanced vane pump (BVP), the effects of air modeling on numerical predictions of discharge flow/pressure ripple and volumetric efficiency have been studied. The tuning time parameters of the model have been correlated to the machine Reynolds number as part of a simplified theoretical background based on dimensional analysis. Considering experimental data at different operating conditions, the tuned model has shown a good capacity in predicting the pressure ripple and the flowrate at the discharge of the pump.

scholarly journals Hydrodynamic analysis and improvement of pontoon boats

2019 ◽  
Vol XXII (1) ◽  
pp. 220-230
Author(s):  
Gürsel K. T.
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Market Share ◽  
Total Pressure ◽  
Hydrodynamic Resistance ◽  
Maximum Speed ◽  
Objective Functions ◽  
Design Features ◽  
Hydrodynamic Properties ◽  
Hydrodynamic Analysis

This study is related to the design features of pontoon boats that enjoy an increasing market share in global recreational boat industry. In this investigation, a representative pontoon boat with three cylindrical buoyancy elements was taken as the model to be studied. Afterwards, the buoyancy elements were improved to optimize hydrodynamic properties using a computational fluid dynamics package. The objective functions were the total hydrodynamic resistance of the boat and the distribution of the turbulence viscosity and total pressure on the hulls. By means of the obtained results, the powering requirements were estimated both for a service speed and for a maximum speed as well as findings were discussed.

A New Alternative for Reduction in Secondary Flows in Low Pressure Turbines

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Diego Torre ◽  
Raúl Vázquez ◽  
Elena de la Rosa Blanco ◽  
Howard P. Hodson
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Physical Phenomenon ◽  
Low Pressure ◽  
Secondary Flows ◽  
Flow Mechanism ◽  
Linear Cascade ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

This paper describes a new flow mechanism for the reduction in secondary flows in low pressure turbines using the benefit of contoured endwalls. The extensive application of contoured endwalls in recent years has provided a deeper understanding of the physical phenomenon that governs the reduction in secondary flows. Based on this understanding, the endwall geometry of a linear cascade of solid-thin profiles typical of low pressure turbines has been redesigned. Experimental data are presented for the validation of this new solution. Based on these data, a reduction of 72% in the secondary kinetic energy helicity (SKEH) and 20% in the mixed-out endwall losses can be obtained. Computational fluid dynamics simulations are also presented to illustrate the effect of the new endwall on the secondary flows. Furthermore, an explanation of the flow mechanism that governs the reduction in the SKEH, and the losses is given.

Numerical Simulation of Human Exposure to Aerosols Generated During Compressed Air Spray-Painting in Cross-Flow Ventilated Booths

2000 ◽  
Vol 123 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Michael R. Flynn ◽  
Eric D. Sills
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Human Exposure ◽  
Cross Flow ◽  
Volatile Oil ◽  
Compressed Air ◽  
Breathing Zone ◽  
Trajectory Data ◽  
Spray Painting ◽  
Numerical Predictions

This paper examines the use of computational fluid dynamics as a tool for predicting human exposure to aerosols generated during compressed air spray painting in cross-flow ventilated booths. Wind tunnel experiments employing a mannequin and non-volatile oil provide data to evaluate the numerical predictions. Fidap (v8.01) is used to calculate the velocity field and particle trajectories, while in-house codes were developed to post-process the trajectory data into mass concentrations, size distributions, transfer efficiency, and over-spray generation rates. The predicted dimensionless breathing-zone concentration of 0.13±23 percent is in agreement with the measured value of 0.13±15 percent given the uncertainties involved in such comparisons. Computational fluid dynamics is a powerful tool capable of providing useful information to occupational hygiene engineers involved in controlling human exposures to toxic airborne contaminants.

Turbine Tone Noise Prediction Using a Linearized Computational Fluid Dynamics Solver: Comparison With Measurements

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Adolfo Serrano González ◽  
José Ramón Fernández Aparicio
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Acoustic Scattering ◽  
Test Facility ◽  
Flat Plates ◽  
Cold Flow ◽  
Flow Noise ◽  
Numerical Predictions ◽  
Near Term ◽  
Cfd Method

The capability of a linearized computational fluid dynamics (CFD) method for predicting turbine tone noise is investigated through comparison with measurements. To start with, a benchmark problem on flat plates is presented, and results are put together with those published by other authors. Then, numerical predictions are compared with measurements from two low-pressure turbines (LPTs), which have been tested in different facilities. The first specimen is a three-stage cold flow rig, noise tested in the Centro de Tecnologías Aeronáuticas (CTA) facility (Bilbao, Spain) in 2012 and funded by the Clean Sky EU Program. The second is the advanced near-term low emissions (ANTLE) LPT rig, full-scale, cold flow, noise tested in the twin shaft test facility (TSTF) in Rolls-Royce (Derby, UK) in 2005 and funded by the SILENCE(R) EU Funded Program. The comparison includes multistage effects, clocking sensitivities, and acoustic scattering through outlet guide vanes (OGVs).

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