scholarly journals A simplified model of a fueldraulic actuation system with application to load estimation

2018 ◽  
Vol 233 (5) ◽  
pp. 570-581
Author(s):  
Tomas Puller ◽  
Andrea Lecchini-Visintini
Keyword(s):  
Simplified Model ◽  
Internal Cooling ◽  
Load Estimation ◽  
Jet Engine ◽  
Input Nonlinearity ◽  
Cooling Flow ◽  
Actuation System ◽  
Mechanical Unit ◽  
Stator Vane ◽  
Variable Stator

In this work, a simplified model of the compressor variable stator vane fueldraulic actuation system of a jet engine is presented. The actuation system is a sub-assembly of the engine’s hydro-mechanical unit. A unique characteristic of the actuator is an internal cooling flow which prevents the overheating of fuel. It is shown that the effect of the cooling flow is well represented by a static input nonlinearity. The resulting model is of the Hammerstein structure. It is then shown that the model can be used for the estimation of the actuator’s external load. The results are validated using an accurate real system simulator.

Effect of an Axially Tilted Variable Stator Vane Platform on Penny Cavity and Main Flow

2021 ◽  
Author(s):  
Johannes Janssen ◽  
Daniel Pohl ◽  
Peter Jeschke ◽  
Alexander Halcoussis ◽  
Rainer Hain ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Flow Region ◽  
Cavity Flow ◽  
Main Flow ◽  
Pressure Probe ◽  
Stator Vane ◽  
Cfd Analyses ◽  
Annular Cascade ◽  
The Impact ◽  
Variable Stator

Abstract This paper presents the impact of an axially tilted variable stator vane platform on penny cavity flow and passage flow, with the aid of both optical and pneumatic measurements in an annular cascade wind tunnel as well as steady CFD analyses. Variable stator vanes (VSVs) in axial compressors require a clearance from the endwalls. This means that penny cavities around the vane platform are inevitable. Production and assembly deviations can result in a vane platform which is tilted about the circumferential axis. Due to this deformation, backward facing steps occur on the platform edge. Penny cavity and main flow in geometries with and without platform tilting were compared in an annular cascade wind tunnel, which comprises a single row of 30 VSVs. Detailed particle image velocimetry (PIV) measurements were conducted inside the penny cavity and in the vane passage. Steady pressure and velocity data was obtained by two-dimensional multi-hole pressure probe traverses in the inflow and the outflow. Furthermore, pneumatic measurements were carried out using pressure taps inside the penny cavity. Additionally, oil flow visualization was conducted on the airfoil, hub, and penny cavity surfaces. Steady CFD simulations with boundary conditions, according to the measurements, have been benchmarked against experimental data. The results show that tilting the VSV platform reduces the mass flow into and out of the penny cavity. By decreasing penny cavity leakage, platform tilting also affects the passage flow where it leads to a reduced turbulence level and total pressure loss in the leakage flow region. In summary, the paper demonstrates the influence of penny platform tilting on cavity flow and passage flow and provides new insights into the mechanisms of penny cavity-associated losses.

The Impact of Blade-to-Blade Flow Variability on Turbine Blade Cooling Performance

2005 ◽  
Vol 127 (4) ◽  
pp. 763-770 ◽  
Author(s):  
Vince Sidwell ◽  
David Darmofal
Keyword(s):  
Turbine Blade ◽  
High Flow ◽  
Low Flow ◽  
Simplified Model ◽  
Selective Assembly ◽  
Turbine Blade Cooling ◽  
Cooling Flow ◽  
Blade Cooling ◽  
Blade Row ◽  
The Impact

The focus of this paper is the impact of manufacturing variability on turbine blade cooling flow and, subsequently, its impact on oxidation life. A simplified flow network model of the cooling air supply system and a row of blades is proposed. Using this simplified model, the controlling parameters which affect the distribution of cooling flow in a blade row are identified. Small changes in the blade flow tolerances (prior to assembly of the blades into a row) are shown to have a significant impact on the minimum flow observed in a row of blades resulting in substantial increases in the life of a blade row. A selective assembly method is described in which blades are classified into a low-flow and a high-flow group based on passage flow capability (effective areas) in life-limiting regions and assembled into rows from within the groups. Since assembling rows from only high-flow blades is equivalent to raising the low-flow tolerance limit, high-flow blade rows will have the same improvements in minimum flow and life that would result from more stringent tolerances. Furthermore, low-flow blade rows are shown to have minimum blade flows which are the same or somewhat better than a low-flow blade that is isolated in a row of otherwise higher-flowing blades. As a result, low-flow blade rows are shown to have lives that are no worse than random assembly from the full population. Using a higher fidelity model for the auxiliary air system of an existing jet engine, the impact of selective assembly on minimum blade flow and life of a row is estimated and shown to be in qualitative and quantitative agreement with the simplified model analysis.

Design and Optimization of the Internal Cooling Channels of a High Pressure Turbine Blade—Part II: Optimization

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Tom Verstraete ◽  
Sergio Amaral ◽  
René Van den Braembussche ◽  
Tony Arts
Keyword(s):  
High Pressure ◽  
Radial Basis Function Network ◽  
Computational Cost ◽  
Optimization Procedure ◽  
Material Model ◽  
Computational Effort ◽  
Internal Cooling ◽  
Optimization System ◽  
Cooling Channels ◽  
Cooling Flow

This second paper presents the aerothermal optimization of the first stage rotor blade of an axial high pressure (HP) turbine by means of the conjugate heat transfer (CHT) method and lifetime model described in Paper I. The optimization system defines the position and diameter of the cooling channels leading to the maximum lifetime of the blade while limiting the amount of cooling flow. It is driven by the results of a CHT and subsequent stress analysis of each newly designed geometry. Both temperature and stress distributions are the input for the Larson–Miller material model to predict the lifetime of the blade. The optimization procedure makes use of a genetic algorithm (GA) and requires the aerothermal analysis of a large number of geometries. Because of the large computational cost of each CHT analysis, this results in a prohibitive computational effort. The latter has been remediated by using a more elaborate optimization system, in which a large part of the CHT analyzes is replaced by approximated predictions by means of a metamodel. Two metamodels, an artificial neural network and a radial basis function network, have been tested and their merits have been discussed. It is shown how this optimization procedure based on CHT calculations, a GA, and a metamodel can lead to a considerable extension of the blade lifetime without an increase in the amount of cooling flow or the complexity of the cooling geometry.

Tip Running Clearances Effects on Tip Vortices Induced Axial Compressor Rotor Flutter

2011 ◽  
Author(s):  
Caetano Peng
Keyword(s):  
Steady State ◽  
Leading Edge ◽  
Steady State Solution ◽  
Tip Vortices ◽  
Flutter Instability ◽  
Compressor Rotor ◽  
Stator Vane ◽  
Blade Tip ◽  
Variable Stator ◽  
Large Rotor

The present study aimed at investigating numerically the effects of large blade tip running clearances on flutter stability of axial core multi-stage compressor rotor. During this study, the influences of aerodynamic boundary conditions, variable stator vane incidence and tip running clearances of upstream and downstream rotors on aerodynamic compressor flow and rotor flutter stability are thoroughly investigated. The simulations were carried out using an in-house 3-D aeroelasticity code. The steady-state-solution computations are performed on single-blade-passage-one-bladerow, stage-blocks and whole compressor models. These analyses included rotor blade models with nominal tip running clearances and artificially large tip clearances. Moreover, the effects of the variable stator vane incidences are assessed by performing steady-state-solution computations for nominal vane schedules and extreme vane malschedule. The first four flap and torsion vibration modes from finite element analyses are included in the unsteady flow computations and assessed for flutter stability. The results from the numerical investigations showed that the compressors with large rotor tip running clearances are susceptible to rotor tip flow induced flutter instability. The aerodynamic losses on the rotor with large tip clearances increase with other rotors having also large tip gaps. For the aerodynamic boundary conditions considered here, the simulations predicted flutter instability for the first flap vibration mode. The flutter instability predicted on the rotors with large tip clearances is driven by oscillating tip vortices on blade suction surface close to the blade tip leading edge. The flow in the rotor tip gap is mostly stalled and tip vortices oscillations are close to blade tip leading edge. The strength of these oscillating vortices appears to increase with increase in variable stator vane malschedule or negative incidence. Small changes in aerodynamic conditions can offset these instabilities. These studies indicate that the main ingredients for the occurrence of these phenomena are likely to be excessively large rotor tip running clearances combined with significant changes in flow incidence.

A Swirl Cooling Flow Experimental Investigation on a Circular Chamber Using Three-Dimensional Stereo-Particle Imaging Velocimetry

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Daisy Galeana ◽  
Asfaw Beyene
Keyword(s):  
Experimental Investigation ◽  
Axial Velocity ◽  
Three Dimensional ◽  
Swirl Flow ◽  
Internal Cooling ◽  
Swirl Number ◽  
Cooling Flow ◽  
Downstream Distance ◽  
Flow Phenomena ◽  
Particle Imaging

Abstract An experimental investigation is presented using three-dimensional (3-D) stereo-particle image velocimetry (stereo-PIV) of a swirl flow that models a gas turbine blade internal cooling configuration. The study is intended to provide an evaluation of the developments of the swirl cooling flow methodology utilizing the 3-D stereo-PIV. The objective is to determine the critical swirl number that has the potential to deliver the maximum axial velocity results. The swirl cooling flow methodology comprises cooling air channeling through the blade’s internal passages lowering the temperature; therefore, the experimental circular chamber is made of acrylic allowing detailed measurements and includes seven discrete tangential jets designed to create the swirl flow. An oil particle seeder (LAVision) is used to provide the particles for velocity measurements while the clear acrylic chamber allows visualization of the flow phenomena. The post-processed data are completed using davis, velocity calculations are conducted in matlab, and techplot is used for data visualization. The focus of this investigation is on the continuous swirl flow that must be sustained via continuous injection of tangential flow at three different Reynolds number, 7000, 14,000, and 21,000, where the swirl flow is generated with seven inlets. Important variations in the swirl number are present near the air inlets and decreases with downstream distance as predicted, since the second half of the chamber has no more inlets. The axial velocity reaches the maximum downstream in the second half of the chamber. The circumferential velocity decreases the downstream distance and reaches the highest toward the center of the chamber.

Numerical Simulation on Ice Accretion Phenomena in Rotor-Stator Interaction Field

2013 ◽  
Author(s):  
Ryosuke Hayashi ◽  
Makoto Yamamoto
Keyword(s):  
Rotor Blade ◽  
Tip Clearance ◽  
Ice Accretion ◽  
Jet Engine ◽  
Tip Leakage ◽  
Interaction Field ◽  
Stator Vane ◽  
Turbine Component ◽  
Rotor Stator Interaction ◽  
Computational Simplicity

Ice accretion is a phenomenon where super-cooled water droplets impinge and accrete on a body. On a jet engine, ice accretion disturbs the inlet flow, and separated ice pieces can damage to the turbine component, which leads to the severe performance degradation. We simulated icing phenomena in a fan rotor-stator interaction field [1]. This study mainly focused on the icing property at the rotor blade, because the maximum ice thickness of the rotor blade is about seven times larger than that of the stator vane. Moreover, in the study, the effect of the tip clearance was neglected because of the computational simplicity. Therefore, in the present study, we simulate icing phenomena in a rotor-stator interaction field, considering the tip clearance, to clarify the effect of the tip clearance on the ice accretion of the stator vane. The numerical results indicate the tip leakage vortex affect the icing phenomenon at the stator vane.

Variable Cycle Powerplants for a Mach 2.7 Supersonic Civil Transport

1996 ◽  
Author(s):  
Louay Aleid ◽  
Pericles Pilidis
Keyword(s):  
Fuel Consumption ◽  
Preliminary Analysis ◽  
Point Of View ◽  
Variable Geometry ◽  
Jet Engine ◽  
Preliminary Results ◽  
Variable Stator ◽  
Size Variable

The aim of the work outlined in this paper is to compare three different variable cycle jet engine concepts for future SSTs. These engines are: the Turbofan-Turbojet, the Mid-Tandem Fan engine and the Double Bypass Engine. The comparison is carried out on a basis of performance, handling and sizing issues. This preliminary analysis compares S.F.C., size, variable geometry and cycle changes, and the effect of variable stator on the running lines of each compressor for each engine. The fuel bill, for two standard missions, is estimated as well. These preliminary results indicate that the three engines are quite similar in terms of general suitability. The Mid Tandem Fan appears to be an attractive proposition from the point of view of sizing, however this comes with a small penalty in fuel consumption.

EFFECT OF AN AXIALLY TILTED VARIABLE STATOR VANE PLATFORM ON PENNY CAVITY AND MAIN FLOW

2021 ◽  
pp. 1-20
Author(s):  
Johannes Janssen ◽  
Daniel Pohl ◽  
Peter Jeschke ◽  
Alexander Halcoussis ◽  
Rainer Hain ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Flow Region ◽  
Cavity Flow ◽  
Main Flow ◽  
Pressure Probe ◽  
Stator Vane ◽  
Cfd Analyses ◽  
Annular Cascade ◽  
The Impact ◽  
Variable Stator

Abstract This paper presents the impact of an axially tilted variable stator vane platform on penny cavity flow and passage flow, with the aid of both optical and pneumatic measurements in an annular cascade wind tunnel as well as steady CFD analyses. Variable stator vanes in axial compressors require a clearance from the endwalls. This means that penny cavities around the vane platform are inevitable. Production and assembly deviations can result in a vane platform which is tilted about the circumferential axis.. Penny cavity and main flow in geometries with and without platform tilting were compared in an annular cascade wind tunnel. Detailed particle image velocimetry measurements were conducted inside the penny cavity and in the vane passage. Steady pressure and velocity data was obtained by two-dimensional multi-hole pressure probe traverses in the inflow and the outflow. Furthermore, pneumatic measurements were carried out using pressure taps inside the penny cavity. Additionally, oil flow visualization was conducted on the airfoil, hub, and penny cavity surfaces. Steady CFD simulations have been benchmarked against experimental data. The results show that tilting the vane platform reduces the penny cavity leakage mass flow. By decreasing penny cavity leakage, platform tilting also affects the passage flow where it leads to a reduced turbulence level and total pressure loss in the leakage flow region. In summary, the paper demonstrates the influence of penny platform tilting on cavity flow and passage flow and provides new insights into the mechanisms of penny cavity-associated losses.

Investigating the friction, wear and damage behaviour of plain bearing bushes of the variable stator vane system

2021 ◽  
pp. 107280
Author(s):  
T. Wollmann ◽  
S. Nitschke ◽  
T. Klauke ◽  
T. Behnisch ◽  
C. Ebert ◽  
...  
Keyword(s):  
Plain Bearing ◽  
Stator Vane ◽  
Variable Stator
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