scholarly journals Detailed Experimental Study of the Flow in a Turbine Rear Structure at Engine Realistic Flow Conditions

2020 ◽  
Author(s):  
Valentin Vikhorev ◽  
Valery Chernoray ◽  
Oskar Thulin ◽  
Srikanth Deshpande ◽  
Jonas Larsson
Keyword(s):  
Suction Side ◽  
Flow Conditions ◽  
Local Flow ◽  
Low Pressure Turbine ◽  
University Of Technology ◽  
Flow Reynolds Number ◽  
Outlet Flow ◽  
Engine Mount ◽  
Inlet Conditions ◽  
Aero Engines

Abstract A good aerodynamic design of the turbine rear structure (TRS) is crucial for improving efficiency and reducing emissions from aero-engines. This paper presents a detailed experimental evaluation of an engine realistic TRS which was studied in an engine-realistic rig at Chalmers University of Technology, Sweden. The TRS test section was equipped with three types of outlet guide vanes (OGVs) which are typical of modern state-of-the-art TRS: regular vanes, thickened vanes and vanes with an engine mount recess (a shroud bump). Each of the three vane geometries were studied under on-design and off-design conditions at a fixed flow Reynolds number of 235,000. The study shows that the off-design performance of the TRS strongly depends on the presence of the local flow separation on the OGV suction side near the hub, which is greatly affected by the vane pressure distribution and inlet conditions. Similarly, the OGVs with increased thickness and with a vane shroud bump are shown to affect the performance of the TRS by influencing the losses on the OGV suction side near the hub. Furthermore, the presence of the bump is shown to have noticeable upstream influence on the outlet flow from the low-pressure turbine and noticeable downstream influence on the outlet flow from the TRS.

scholarly journals Detailed Experimental Study of the Flow in a Turbine Rear Structure at Engine-Realistic Flow Conditions

2021 ◽  
pp. 1-11
Author(s):  
Valentin Vikhorev ◽  
Valery Chernoray ◽  
Oskar Thulin ◽  
Srikanth Deshpande ◽  
Jonas Larsson
Keyword(s):  
Suction Side ◽  
Flow Conditions ◽  
Local Flow ◽  
Low Pressure Turbine ◽  
University Of Technology ◽  
Flow Reynolds Number ◽  
Outlet Flow ◽  
Engine Mount ◽  
Inlet Conditions ◽  
Aero Engines

Abstract A good aerodynamic design of the turbine rear structure (TRS) is crucial for improving efficiency and reducing emissions from aero-engines. This paper presents a detailed experimental evaluation of an engine realistic TRS which was studied in an engine-realistic rig at Chalmers University of Technology, Sweden. The TRS test section was equipped with three types of outlet guide vanes (OGVs) which are typical of modern state-of-the-art TRS: regular vanes, thickened vanes and vanes with an engine mount recess (a shroud bump). Each of the three vane geometries were studied under on-design and off-design conditions at a fixed flow Reynolds number of 235,000. The study shows that the off-design performance of the TRS strongly depends on the presence of the local flow separation on the OGV suction side near the hub, which is greatly affected by the vane pressure distribution and inlet conditions. Similarly, the OGVs with increased thickness and with a vane shroud bump are shown to affect the performance of the TRS by influencing the losses on the OGV suction side near the hub. Furthermore, the presence of the bump is shown to have noticeable upstream influence on the outlet flow from the low-pressure turbine and noticeable downstream influence on the outlet flow from the TRS.

scholarly journals Experimental Investigations of the Influence of Incoming Wakes on the Losses of a Linear Turbine Cascade

1993 ◽  
Author(s):  
M. Ladwig ◽  
L. Fottner
Keyword(s):  
Suction Side ◽  
Reynolds Numbers ◽  
Experimental Investigations ◽  
Turbine Cascade ◽  
Flow Conditions ◽  
Inlet Flow ◽  
Low Reynolds Numbers ◽  
Blade Passage ◽  
Inlet Conditions ◽  
Hot Film

The objective of this work is to enhance the understanding of the influence of wake induced non-uniform, steady inlet flow conditions on the profile losses of highly-loaded turbines. For different Reynolds numbers wake and profile pressure distribution measurements were carried out on a linear subsonic turbine cascade as well as measurements with a single sensor hot-film probe. The non-uniform inlet flow were simulated with two different cascades of cylindrical bars. The measurements with various circumferential positions of the incoming wakes relative to the turbine cascade show at low Reynolds numbers a decrease of the losses compared to uniform inlet conditions, because no separation of the suction side boundary layer occurs. With increasing Reynolds numbers the non-uniform inlet flow conditions cause an increase in the losses compared to uniform inlet conditions, due to the forward shift of transition. Generally, the smallest influence of the non-uniform incoming flow can be observed when the wakes enter the cascade inlet plane between the pressure-side of the profiles and the middle of the blade passage. Incoming wakes have the highest influence when they enter the blade passage near to the suction side of the profiles.

Comparison of the Aerodynamics of Acoustically Designed EGVs and a State-of-the-Art EGV

2014 ◽  
Author(s):  
Andreas Marn ◽  
Thorsten Selic ◽  
Florian Schönleitner ◽  
Franz Heitmeir ◽  
Dominik Broszat
Keyword(s):  
State Of The Art ◽  
Power Level ◽  
Operating Point ◽  
Guide Vanes ◽  
Acoustic Design ◽  
Low Pressure Turbine ◽  
Sound Power Level ◽  
University Of Technology ◽  
Aero Engines ◽  
Engine Operating Point

Within previous EU projects, possible modifications to the engine architecture have been investigated, that would allow for an optimised aerodynamic or acoustic design of the exit guide vanes (EGV) of the turbine exit casing (TEC). However, the engine weight should not be increased and the aerodynamic performance must be at least the same. This paper compares a state-of-the art TEC (reference TEC) with typical EGVs with an acoustically optimised TEC configuration for the engine operating point approach. It is shown that a reduction in sound power level for the fundamental tone (1 blade passing frequency) for this acoustically important operating point can be achieved. It is also shown that the weight of the acoustically optimised EGVs (only bladings considered) is almost equal to the Reference TEC, but a reduction in engine length can be achieved. Measurements were conducted in the subsonic test turbine facility (STTF) at the Institute for Thermal Turbomachinery and Machine Dynamics, Graz University of Technology. The inlet guide vanes, the low pressure turbine (LPT) stage, and the EGVs have been designed by MTU Aero Engines.

Comparison of the Aerodynamics of Acoustically Designed Exit Guide Vanes and a State-of-the-Art Exit Guide Vane

2014 ◽  
Vol 137 (4) ◽  
Author(s):  
Andreas Marn ◽  
Dominik Broszat ◽  
Thorsten Selic ◽  
Florian Schönleitner ◽  
Franz Heitmeir
Keyword(s):  
State Of The Art ◽  
Guide Vane ◽  
Power Level ◽  
Operating Point ◽  
Guide Vanes ◽  
Low Pressure Turbine ◽  
Sound Power Level ◽  
University Of Technology ◽  
Aero Engines ◽  
Engine Operating Point

Within previous EU projects, possible modifications to the engine architecture have been investigated, which would allow for an optimized aerodynamic or acoustic design of the exit guide vanes (EGVs) of the turbine exit casing (TEC). However, the engine weight should not be increased and the aerodynamic performance must be at least the same. This paper compares a state-of-the art TEC (reference TEC) with typical EGVs with an acoustically optimized TEC configuration for the engine operating point approach. It is shown that a reduction in sound power level for the fundamental tone (one blade passing frequency (BPF)) for this acoustically important operating point can be achieved. It is also shown that the weight of the acoustically optimized EGVs (only bladings considered) is almost equal to the reference TEC, but a reduction in engine length can be achieved. Measurements were conducted in the subsonic test turbine facility (STTF) at the Institute for Thermal Turbomachinery and Machine Dynamics, Graz University of Technology. The inlet guide vanes (IGVs), the low pressure turbine (LPT) stage, and the EGVs have been designed by MTU Aero Engines.

The Effect of Pulsed Blowing on the Boundary Layer of a Highly Loaded Low Pressure Turbine Blade

2013 ◽  
Author(s):  
Marion Mack ◽  
Roland Brachmanski ◽  
Reinhard Niehuis
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Mach Number ◽  
Suction Side ◽  
Reynolds Numbers ◽  
Low Pressure ◽  
Trailing Edge ◽  
Low Pressure Turbine ◽  
Wide Range ◽  
Highly Loaded

The performance of the low pressure turbine (LPT) can vary appreciably, because this component operates under a wide range of Reynolds numbers. At higher Reynolds numbers, mid and aft loaded profiles have the advantage that transition of suction side boundary layer happens further downstream than at front loaded profiles, resulting in lower profile loss. At lower Reynolds numbers, aft loading of the blade can mean that if a suction side separation exists, it may remain open up to the trailing edge. This is especially the case when blade lift is increased via increased pitch to chord ratio. There is a trend in research towards exploring the effect of coupling boundary layer control with highly loaded turbine blades, in order to maximize performance over the full relevant Reynolds number range. In an earlier work, pulsed blowing with fluidic oscillators was shown to be effective in reducing the extent of the separated flow region and to significantly decrease the profile losses caused by separation over a wide range of Reynolds numbers. These experiments were carried out in the High-Speed Cascade Wind Tunnel of the German Federal Armed Forces University Munich, Germany, which allows to capture the effects of pulsed blowing at engine relevant conditions. The assumed control mechanism was the triggering of boundary layer transition by excitation of the Tollmien-Schlichting waves. The current work aims to gain further insight into the effects of pulsed blowing. It investigates the effect of a highly efficient configuration of pulsed blowing at a frequency of 9.5 kHz on the boundary layer at a Reynolds number of 70000 and exit Mach number of 0.6. The boundary layer profiles were measured at five positions between peak Mach number and the trailing edge with hot wire anemometry and pneumatic probes. Experiments were conducted with and without actuation under steady as well as periodically unsteady inflow conditions. The results show the development of the boundary layer and its interaction with incoming wakes. It is shown that pulsed blowing accelerates transition over the separation bubble and drastically reduces the boundary layer thickness.

Design of an Intermediate Turbine Duct Downstream of a High Pressure Turbine

2016 ◽  
Author(s):  
Chaoshan Hou ◽  
Hu Wu
Keyword(s):  
High Pressure ◽  
Three Dimensional ◽  
Low Pressure ◽  
Aerodynamic Load ◽  
Duct Flow ◽  
Original Design ◽  
High Pressure Turbine ◽  
Intermediate Turbine Duct ◽  
Low Pressure Turbine ◽  
Inlet Conditions

The flow leaving the high pressure turbine should be guided to the low pressure turbine by an annular diffuser, which is called as the intermediate turbine duct. Flow separation, which would result in secondary flow and cause great flow loss, is easily induced by the negative pressure gradient inside the duct. And such non-uniform flow field would also affect the inlet conditions of the low pressure turbine, resulting in efficiency reduction of low pressure turbine. Highly efficient intermediate turbine duct cannot be designed without considering the effects of the rotating row of the high pressure turbine. A typical turbine model is simulated by commercial computational fluid dynamics method. This model is used to validate the accuracy and reliability of the selected numerical method by comparing the numerical results with the experimental results. An intermediate turbine duct with eight struts has been designed initially downstream of an existing high pressure turbine. On the basis of the original design, the main purpose of this paper is to reduce the net aerodynamic load on the strut surface and thus minimize the overall duct loss. Full three-dimensional inverse method is applied to the redesign of the struts. It is revealed that the duct with new struts after inverse design has an improved performance as compared with the original one.

Improving Characteristics of a Cooled Transonic Vane of Low Pressure Turbine Under Nonuniform Inlet Conditions

2021 ◽  
Author(s):  
Igor Afanasiev ◽  
Valery Kostezh ◽  
Evgeny Marchukov ◽  
Andrey Granovskiy
Keyword(s):  
Low Pressure ◽  
Low Pressure Turbine ◽  
Inlet Conditions

Experimental and Numerical Investigations on Flow Characteristics of the KVLCC2 at 30° Drift Angl

2015 ◽  
Author(s):  
Moustafa Abdel-Maksoud ◽  
Volker Müller ◽  
Tao Xing ◽  
Serge Toxopeus ◽  
Frederick Stern ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Turbulence Modeling ◽  
Flow Characteristics ◽  
Flow Structures ◽  
Local Flow ◽  
Drift Angle ◽  
Vortical Structures ◽  
Ship Model ◽  
University Of Technology ◽  
Global And Local

Investigations of flow characteristics around ship hulls at large drift angle are very important for understanding the motion behavior of ships during maneuvers. At large drift angles, the flow is dominated by strong vortical structures and complex three-dimensional separations. An accurate prediction of these flow structures is still a challenge for modern computational fluid dynamics (CFD) solvers. Hull forms with high block coefficients are blunt and have strong curvatures, which leads to large area flow separations over smooth surfaces. These areas are sensitive to the relative angle between the flow and the ship motion direction. The paper is concerned with a collaborative computational study of the flow behavior around a double model of KVLCC2 at 30 degrees drift angle and Fr=0 condition, including analysis of numerical methods, turbulence modeling and grid resolution, and their effects on the mean flow and separation onset as well as formation of the vortical structures. This research is an outcome of a multi-year collaboration of five research partners from four countries. The overall approach adopted for the present study combines the advantages of CFD and EFD with the ultimate goal of capturing the salient details of the flow around the bluff hull form. The experiments were performed at the low - speed wind tunnel of the Hamburg University of Technology (TUHH). The main features of the global and local flow were captured in the experimental study. To determine the global flow characteristics, two different flow visualization techniques were used. The first one is a smoke test, which allows the visualization of vortex structures in vicinity of the ship model. The second test is a classic oil film method, which yields the direction of the limiting wall streamlines on the surface of the model. The analysis of the experimental results helped identify the separation zones on the ship model. To resolve the local flow-fields, LDA and PIV measurements were carried out in a selected number of measuring sections. Subsequently, the EFD and CFD results for the global and local flow structures were compared and analyzed. The numerical simulations were carried out by 5 institutions: Iowa Institute of Hydraulic Research of the University of Iowa (IIHR), USA, Maritime Research Institute Netherlands (MARIN), The Netherlands, Hamburg University of Technology (TUHH), Germany, Naval Surface Warfare Center, Carderock Division (NSWCCD) West Bethesda, USA and Swedish Defense Research Agency (FOI), Sweden. For the comparison with the experimental results, seven submissions of steady and unsteady CFD results are included in the present study. The participating codes include CFDShip-Iowa, ReFRESCO, FreSCo+, Edge, OpenFOAM (FOI) and NavyFoam. The size of the computational grids varies between 11 and 202 million control volumes or nodes. The influence of turbulence modeling on the predicted flow is studied by a wide variety of models such as isotropic eddy viscosity models of k-w family, Explicit Algebraic Reynolds Stress Model (EARSM), hybrid RANS-LES (DES), and LES. Despite notable differences in the grid resolutions, numerical methods, and turbulence models, the global features of the flow are closely captured by the computations. Noticeable differences among the computations are found in the details of the local flow such as the vortex strength and the location and extent of the flow separations.

Impact of Individual High-Pressure Turbine Rotor Purge Flows on Turbine Center Frame Aerodynamics

2017 ◽  
Author(s):  
S. Zerobin ◽  
C. Aldrian ◽  
A. Peters ◽  
F. Heitmeir ◽  
E. Göttlich
Keyword(s):  
High Pressure ◽  
Pressure Loss ◽  
Turbine Rotor ◽  
Flow Conditions ◽  
High Pressure Turbine ◽  
Reference Case ◽  
University Of Technology ◽  
Purge Flow ◽  
Generation Mechanisms ◽  
The Impact

This paper presents an experimental study of the impact of individual high-pressure turbine purge flows on the main flow in a downstream turbine center frame duct. Measurements were carried out in a product-representative one and a half stage turbine test setup, installed in the Transonic Test Turbine Facility at Graz University of Technology. The rig allows testing at engine-relevant flow conditions, matching Mach, Reynolds, and Strouhal number at the inlet of the turbine center frame. The reference case features four purge flows differing in flow rate, pressure, and temperature, injected through the hub and tip, forward and aft cavities of the high-pressure turbine rotor. To investigate the impact of each individual cooling flow on the flow evolution in the turbine center frame, the different purge flows were switched off one-by-one while holding the other three purge flow conditions. In total, this approach led to six different test conditions when including the reference case and the case without any purge flow ejection. Detailed measurements were carried out at the turbine center frame duct inlet and outlet for all six conditions and the post-processed results show that switching off one of the rotor case purge flows leads to an improved duct performance. In contrast, the duct exit flow is dominated by high pressure loss regions if the forward rotor hub purge flow is turned off. Without the aft rotor hub purge flow, a reduction in duct pressure loss is determined. The purge flows from the rotor aft cavities are demonstrated to play a particularly important role for the turbine center frame aerodynamic performance. In summary, this paper provides a first-time assessment of the impact of four different purge flows on the flow field and loss generation mechanisms in a state-of-the-art turbine center frame configuration. The outcomes of this work indicate that a high-pressure turbine purge flow reduction generally benefits turbine center frame performance. However, the forward rotor hub purge flow actually stabilizes the flow in the turbine center frame duct and reducing this purge flow can penalize turbine center frame performance. These particular high-pressure turbine/turbine center frame interactions should be taken into account whenever high-pressure turbine purge flow reductions are pursued.

An Experimental Investigation of the Effect of Freestream Turbulence on the Wake of a Separated Low-Pressure Turbine Blade at Low Reynolds Numbers

1999 ◽  
Vol 122 (2) ◽  
pp. 431-433 ◽  
Author(s):  
C. G. Murawski ◽  
K. Vafai
Keyword(s):  
Reynolds Number ◽  
Turbine Blade ◽  
Turbulence Intensity ◽  
Reynolds Numbers ◽  
Low Pressure ◽  
Freestream Turbulence ◽  
Suction Surface ◽  
Low Reynolds Numbers ◽  
Low Pressure Turbine ◽  
Flow Reynolds Number

An experimental study was conducted in a two-dimensional linear cascade, focusing on the suction surface of a low pressure turbine blade. Flow Reynolds numbers, based on exit velocity and suction length, have been varied from 50,000 to 300,000. The freestream turbulence intensity was varied from 1.1 to 8.1 percent. Separation was observed at all test Reynolds numbers. Increasing the flow Reynolds number, without changing freestream turbulence, resulted in a rearward movement of the onset of separation and shrinkage of the separation zone. Increasing the freestream turbulence intensity, without changing Reynolds number, resulted in shrinkage of the separation region on the suction surface. The influences on the blade’s wake from altering freestream turbulence and Reynolds number are also documented. It is shown that width of the wake and velocity defect rise with a decrease in either turbulence level or chord Reynolds number. [S0098-2202(00)00202-9]

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