A Comprehensive Investigation of Preswirled Flow Through Rotating Radial Holes

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Daniel Riedmüller ◽  
Jan Sousek ◽  
Michael Pfitzner
Keyword(s):  
Experimental Data ◽  
Gas Turbines ◽  
Discharge Coefficient ◽  
Cfd Simulation ◽  
Test Rig ◽  
Outer Annulus ◽  
Flow Phenomena ◽  
Flow Through ◽  
Flow Directions ◽  
Experimental Findings

This paper reports on the flow (centrifugal = radially outward, centripetal = radially inward) through rotating radial orifices with and without preswirl in the flow approaching the orifice in the outer annulus. The aerodynamical behavior of flow through radial rotating holes is different from the one through axial and stationary holes due to the presence of centrifugal and Coriolis forces. To investigate the flow phenomena and the discharge coefficient of these orifices in detail, an existing test rig containing two independently rotating shafts (corotating and counter rotating) was used. To simulate conditions of real gas turbines, where the flow is often influenced by upstream components, various preswirl angles were used in the test rig. Measurements of the flow discharge coefficient in both flow directions through the orifices (centripetal and centrifugal), with and without preswirl generation in the outer annulus, are presented at various flow conditions (pressure ratios across orifices, Mach numbers of approaching flow) and for different geometric parameters (length to diameter ratios, sharp/rounded inlet edges). Flow effects that occur with preswirled flow are clarified. A comparison of the experimental data, for both flow directions, shows a similar behavior of the discharge coefficients with increasing shaft speeds. To supplement the experimental data and to better understand the experimental findings, numerical simulations were performed, which show a good agreement with the experimental results. Furthermore, an optimization model with complete automatic grid generation, computational fluid dynamics (CFD) simulation, and postprocessing, was built to enable large parametric studies, e.g., grid independence of the solutions.

A Comprehensive Investigation of Pre-Swirled Flow Through Rotating Radial Holes

2014 ◽  
Author(s):  
Daniel Riedmüller ◽  
Jan Sousek ◽  
Michael Pfitzner
Keyword(s):  
Experimental Data ◽  
Gas Turbines ◽  
Discharge Coefficient ◽  
Cfd Simulation ◽  
Test Rig ◽  
Outer Annulus ◽  
Flow Through ◽  
Flow Directions ◽  
Experimental Findings ◽  
Swirled Flow

This paper reports on the flow (centrifugal = radially outwards, centripetal = radially inwards) through rotating radial orifices with and without pre-swirl in the flow approaching the orifice in the outer annulus. The aerodynamical behavior of flow through radial rotating holes is different from the one through axial and stationary holes due to the presence of centrifugal and Coriolis forces. To investigate the flow phenomena and the discharge coefficient of these orifices in detail, an existing test rig containing two independently rotating shafts (co- and counter rotating) was used. To simulate conditions of real gas turbines, where the flow is often influenced by upstream components, various pre-swirl angles were used in the test rig. Measurements of the flow discharge coefficient in both flow directions through the orifices (centripetal and centrifugal), with and without pre-swirl generation in the outer annulus, are presented at various flow conditions (pressure ratios across orifices, Mach numbers of approaching flow) and for different geometric parameters (length to diameter ratios, sharp/rounded inlet edges). Flow effects, that occur with pre-swirled flow are clarified. A comparison of the experimental data, for both flow directions, shows a similar behavior of the discharge coefficients with increasing shaft speeds. To supplement the experimental data and to better understand the experimental findings, numerical simulations were performed, which show a good agreement with the experimental results. Furthermore, an optimization model with complete automatic grid generation, CFD simulation and post-processing, was built to enable large parametric studies e.g. grid independence of the solutions.

Unsteady 3D-Numerical Investigation of the Influence of the Blading Design on the Stator-Rotor Interaction in a 2-Stage Turbine

2005 ◽  
Author(s):  
Dieter E. Bohn ◽  
Jing Ren ◽  
Christian Tu¨mmers ◽  
Michael Sell
Keyword(s):  
Gas Turbines ◽  
Flow Characteristics ◽  
Computer Code ◽  
Experimental Investigations ◽  
Blade Design ◽  
Test Rig ◽  
3D Flow ◽  
Two Stage ◽  
Flow Phenomena ◽  
Flow Through

An important goal in the development of turbine bladings is improving their efficiency to achieve an optimized usage of energy resources. This requires a detailed insight into the complex 3D-flow phenomena in multi-stage turbines. In order to investigate the flow characteristics of modern highly loaded turbine profiles, a test rig with a two-stage axial turbine has been set up at the Institute of Steam and Gas Turbines, Aachen University. The test rig is especially designed to investigate different blading designs. In order to analyze the influence of the blade design on the unsteady blade row interaction, the 3D flow through the two-stage turbine is simulated numerically, using an unsteady Navier-Stokes computer code. The investigations include a comparison of two bladings with different design criteria. The reference blading is a commonly used cylindrical designed blading. This blade design will be compared with a bow-blading, which is designed to minimize the secondary flow phenomena near the endwall in order to achieve a balanced mass flow through nearly the whole passage height. The investigations will focus on the different loss behavior of the two bladings. Unsteady profile pressure distributions and radial efficiencies of the two blade designs will be discussed in detail. The flow conditions are taken from experimental investigations performed at the Institute of Steam and Gas Turbines. On the basis of the experiments a validation of the code will be performed by comparing the numerical results to the corresponding experimental data at the inlet and the outlet of the blading.

Effect of Shaft Rotation, Hole and Annulus Geometry on the Discharge Behavior Through Rotating Radial Holes

2015 ◽  
Author(s):  
Daniel Riedmüller ◽  
Jan Sousek ◽  
Michael Pfitzner
Keyword(s):  
Discharge Coefficient ◽  
Cfd Simulation ◽  
Flow Direction ◽  
Flow Behavior ◽  
Pressure Ratio ◽  
Flow Phenomena ◽  
Flow Through ◽  
Discharge Behavior ◽  
Set Up ◽  
The One

This paper reports on various effects on the flow through rotating radial holes (centrifugal, centripetal) in conjunction with the geometries of hole and surrounding annuli. The aerodynamic behavior of radial rotating holes is different from the one of axial and stationary holes due to the presence of centrifugal and Coriolis forces acting in the main flow direction. Furthermore, the geometry of the inlet and outlet region is often influencing the separation behavior of the flow at the holes. To investigate the flow phenomena and the discharge behavior of these radial holes in detail, an existing test rig containing two independently rotating shafts (co- and counter rotating) was used. Experimental and numerical investigations have been performed for both flow directions through the radial holes (centripetal and centrifugal), for different hole geometries (oblong holes and round holes), inlet types (rounded and sharp), length to diameter ratios (variation of either length or diameter) and gap widths between inner and outer shaft. For each of these geometrical variations flow properties have been varied such as pressure ratio across the holes, incident Mach number and rotational speed of both shafts. To enable large parametric studies and grid independency studies an optimization model with completely automatic grid generation, CFD simulation and post-processing has been set up. As a main result of the current studies it was found, that the shaft to hole diameter is another parameter of interest for the flow behavior through shaft holes. For a centripetal flow through the shaft holes and a decreasing inner gap width, the discharge coefficient was observed to increase initially before it drops significantly. In addition, measurements of centripetal flow though oblong holes revealed higher discharge coefficient in comparison with round holes and equal length to diameter ratio.

scholarly journals Development of a new test rig for the analysis of hydrodynamic bearings for rotors of microGT

2019 ◽  
Vol 113 ◽  
pp. 03002
Author(s):  
Carlo Alberto Niccolini Marmont Du Haut Champ ◽  
Fabrizio Stefani ◽  
Paolo Silvestri
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Gas Turbines ◽  
Dynamic Interaction ◽  
Journal Bearings ◽  
Radial Clearance ◽  
Test Rig ◽  
Small Clearance ◽  
Stiffness And Damping ◽  
Good Agreement

The aim of the present work is to design a test rig suited to investigate the dynamic interaction between rotor and hydrodynamic journal bearings in micro gas turbines (microGT), i.e. with reference to small bearings (diameter in the order of ten millimeters). Particularly, the device is capable of measuring the journal location. Therefore, the journal motion due to rotor vibrations can be displayed, in order to assess performance as well as stiffness and damping of the bearings. The new test rig is based on Bently Nevada Rotor Kit (RK), but substantial modifications are carried out. Indeed, the relative radial clearance of the original RK bearings is about 2/100, while it is in the order of 1/1000 in industrial bearings. Therefore, the same RK bearings are employed in the new test rig, but a new shaft has been designed in order to reduce the original clearance. The new shaft enables us to study the bearing behaviour for different clearances, as it is equipped with interchangeable journals. The experimental data yielded by the new test rig are compared with numerical results. These are obtained by means of a suitable finite element (FEM) code developed by our research group. It allows the Thermo Elasto-HydroDynamic (TEHD) analysis of the bearing in static and dynamic conditions. In the present paper, bearing static performances are analysed in order to assess the reliability of the journal location predictions by comparing numerical and experimental results. Such comparisons are presented for both large and small clearance bearings of original and modified RK, respectively. Good agreement is found only for the modified RK equipped with small clearance bearings (relative radial clearance equal to 8/1000). Nevertheless, rotor alignment is quite difficult with small clearance bearings and a completely new test rig is designed for future experiments.

Simulation of Wall Pressure Fluctuations on Simplified Automobile Shapes Using a Lattice Based Method

2005 ◽  
Author(s):  
Sivapalan Senthooran ◽  
Bernd Crouse ◽  
Ganapathi Balasubramanian ◽  
David Freed ◽  
Swen Noelting ◽  
...  
Keyword(s):  
Experimental Data ◽  
Numerical Scheme ◽  
Cfd Simulation ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Complex Flow ◽  
Wall Pressure Fluctuations ◽  
Flow Phenomena ◽  
High Reynolds ◽  
Rng Turbulence Model

A comparison of experimental data and CFD simulation results of wall pressure fluctuations on simplified geometries that generate flow structures similar to an automobile are presented. The numerical results have been obtained using the commercial software PowerFLOW 3.4p4a. The simulation kernel of this software is based on the numerical scheme known as the Lattice Boltzmann Method (LBM), combined with an RNG turbulence model. This scheme accurately captures time-dependent aerodynamic behavior of high Reynolds number flows over complex geometries, together with the acoustics. The geometries considered for this study represent the green house and the side mirror of a car. Spectral analysis is performed on the simulation data and the results are compared to the experimental data. This comparison provides good correlation between the simulation and experiment, and demonstrates the capability of this numerical scheme in predicting turbulent fluctuations due to complex flow phenomena.

Experimental Study on Pressure Losses in Circular Orifices for the Application in Internal Cooling Systems

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Christian Binder ◽  
Mats Kinell ◽  
Esa Utriainen ◽  
Daniel Eriksson ◽  
Mehdi Bahador ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Discharge Coefficient ◽  
Air Flow ◽  
Internal Cooling ◽  
Cooling Systems ◽  
Pressure Losses ◽  
Flow Through ◽  
Cooling Air Flow ◽  
New Phenomena ◽  
Cooling Air

The cooling air flow in a gas turbine is governed by the flow through its internal passages and controlled by restrictors such as circular orifices. If the cooling air flow is incorrectly controlled, the durability and mechanical integrity of the whole turbine may be affected. Consequently, a good understanding of the orifices in the internal passages is important. This study presents experimental results for a range of pressure ratios and length-to-diameter ratios common in gas turbines including even very small pressure ratios. Additionally, the chamfer depth at the inlet was also varied. The results of the chamfer depth variation confirmed its beneficial influence on decreasing pressure losses. Moreover, important effects were noted when varying more than one parameter at a time. Besides earlier mentioned hysteresis at the threshold of choking, new phenomena were observed, e.g., a rise of the discharge coefficient for certain pressure and length-to-diameter ratios. A correlation for the discharge coefficient was attained based on the new experimental data with a generally lower error than previous studies.

A Rim Seal Orifice Model With 2 Cds and Effects of Swirl in Seals

2008 ◽  
Author(s):  
Bruce V. Johnson ◽  
Cheng-Zhang Wang ◽  
Ramendra P. Roy
Keyword(s):  
Experimental Data ◽  
Flow Condition ◽  
Gas Turbines ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Outer Region ◽  
Outer Radius ◽  
Lumped Parameter ◽  
Flow Through ◽  
Two Parameters

Rim seal ingestion models for gas turbines are formulated to estimate the amount of hot fluid ingested through “clearance” seals into the disk cavity. Previous numerical and experimental studies showed the complex time-dependent, three-dimensional characteristics of the flow through the seals and in the outer region of the disk cavity. The present model is developed for estimating ingress and egress flow through the seal that is driven by the azimuthal variation in gas path pressure near the vane and blade platforms. Most published rim seal orifice models have used one “lumped parameter” Cd for both ingress and egress across the seal. However, the flow path from the gas path through the seal is often more convoluted than the flow returning to the gas path. The present Rim Seal Orifice Model includes (i) a Cd value for ingress from the gas path into the disk cavity, (ii) a Cd value for egress from the disk cavity to the gas path and (iii) an estimate for effects of swirl from the seal outer radius to the inner radius of the seal mixing region. The use of two Cd values provides two parameters for characterizing the flow through the seal. The ingress and egress Cd values for a turbine rim seal configuration and flow condition are estimated by comparing the modeled seal effectiveness for a parametric range of ingress and egress Cd values with experimental stator wall measurements. The combination of Cd values, which best matches experimental data over a range of coolant flow ratios, characterizes the seal and flow condition. Arizona State University experimental data were used to estimate the Cd values for an overlap seal configuration.

CFD Simulation of a Microturbine Annular Combustion Chamber Fuelled With Methane and Biomass Pyrolysis Syngas: Preliminary Results

2009 ◽  
Author(s):  
Francesco Fantozzi ◽  
Paolo Laranci ◽  
Michele Bianchi ◽  
Andrea De Pascale ◽  
Michele Pinelli ◽  
...  
Keyword(s):  
Experimental Data ◽  
Natural Gas ◽  
Combustion Chamber ◽  
Gas Turbines ◽  
Cfd Simulation ◽  
Combustion Process ◽  
Calorific Value ◽  
Methane Combustion ◽  
Pollutant Emissions ◽  
Preliminary Results

Micro gas turbines could be profitably used, for distributed energy production, also exploiting low calorific value biomass-derived fuels, obtained by means of integrated pyrolysis and/or gasification processes. These synthesis gases show significant differences with respect to natural gas (in terms of composition, low calorific value, hydrogen content, tar and particulate matter content) that may turn into ignition problems, combustion instabilities, difficulties in emission control and fouling. CFD simulation of the combustion chamber is a key instrument to identify main criticalities arising when using these gases, in order to modify existing geometries and to develop new generation combustion chambers for use with low calorific value gases. This paper describes the numerical activity carried out to analyze the combustion process occurring inside an existing microturbine annular combustor. A CFD study of the combustion process performed with different computational codes is introduced and some preliminary results are reported in the paper. A comparison of results obtained with the different codes is provided, for the reference case of methane combustion. A first evaluation of the pollutant emissions and a comparison with the available experimental data is also provided in the paper, showing in particular a good matching of experimental data on NOx emissions at different load conditions. Moreover, the carried out investigation concerns the case of operation with a syngas fuel derived from pyrolysis of biomass and finally the case of syngas and natural gas co-firing. This combustion condition is simulated with a simple reduced chemical kinetic scheme, in order to assess only the key issues rising with this fuel in comparison with the case of methane combustion. The analysis shows that in case of syngas operation the combustor internal temperature hot spots are reduced and the primary zone flame tends to stabilize closer to the injector, with possible implications on the emission release.

Comparison of 2D and 3D Airfoils in Combination With Non Axisymmetric End Wall Contouring: Part 1 — Experimental Investigations

2016 ◽  
Author(s):  
Tobias W. Zimmermann ◽  
Oliver Curkovic ◽  
Manfred Wirsum ◽  
Andrew Fowler ◽  
Kush Patel
Keyword(s):  
Gas Turbines ◽  
Experimental Investigations ◽  
Test Rig ◽  
Second Stage ◽  
Beneficial Impact ◽  
Flow Phenomena ◽  
2D And 3D ◽  
End Wall ◽  
Constant Section ◽  
Turbine Blading

Tangential end wall contouring is intended to improve turbomachinery blading efficiency. This paper is the first of a series of two papers. It summarizes the experimental investigation of a test turbine with end wall contoured vanes and blades. Constant section airfoils as well as optimized 3D high pressure steam turbine blading in baseline and end wall contoured configurations have been examined in a 2 stage axial turbine test rig at the Institute of Power Plant Technology, Steam and Gas Turbines (IKDG) of RWTH Aachen University. The test rig is driven with air. Brush seals are implemented within the casing sided cavities to minimize the leakage flow near the tip end walls, where the contouring is also applied. The pressure and temperature data that is recorded in three axial measuring planes are plotted to visualize the change in flow structure. This has shown that the efficiency is increased for 2D airfoils by means of end wall contouring, which is caused by a homogenized inflow to the second stage. However the efficiency of the first stage suffers, the end wall contouring is beneficial for the performance of the engine. Both phenomena (an efficiency loss in stage one and an improvement of the performance in stage two) have also been measured for the optimized 3D configurations thus it can be expected that end wall contouring has also a beneficial impact on the performance of multi row turbines. The second part of this paper presents the results of numerical investigations of end-wall contoured blades. It will demonstrate how the secondary flow phenomena are influenced by end-wall contours. The simulations are validated with measured data from the test rig.

scholarly journals COMPARISON OF AXIAL FAN ROTOR EXPERIMENTAL DATA WITH CFD SIMULATION

2016 ◽  
Vol 56 (1) ◽  
pp. 62 ◽  
Author(s):  
Aleš Prachař
Keyword(s):  
Experimental Data ◽  
Boundary Conditions ◽  
Cfd Simulation ◽  
Free Stream ◽  
Calculated Data ◽  
Experimental Simulation ◽  
Test Rig ◽  
Axial Fan ◽  
Axial Fans ◽  
Adequate Agreement

Data obtained from an experimental simulation on a new test rig for axial fans are compared to a CFD simulation. The Edge solver is used and the development needed for the simulation (boundary conditions, free stream consistency) is described. Adequate agreement between the measured and calculated data is observed.

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