Experimental Investigation of the Noise Generation and Propagation for Different Turning Mid Turbine Frame Setups in a Two-Stage Two-Spool Test Turbine

2013 ◽  
Author(s):  
C. Faustmann ◽  
D. Lengani ◽  
R. Spataro ◽  
A. Marn ◽  
E. Göttlich ◽  
...  
Keyword(s):  
Microphone Array ◽  
Low Pressure ◽  
Open Circuit ◽  
Noise Generation ◽  
Turbine Stage ◽  
Noise Emission ◽  
Two Stage ◽  
Low Pressure Turbine ◽  
Lp Turbine ◽  
Eu Project

The paper deals with the investigation of the noise generation in the two-stage two-spool test turbine located at the Institute for Thermal Turbomachinery and Machine Dynamics (ITTM) at Graz University of Technology. The rig went into operation within the EU-project DREAM, where the target was to investigate the aerodynamics of interturbine flow ducts. The facility is a continuously operating cold-flow open-circuit plant which is driven by pressurized air. The flow path contains a transonic turbine stage (HP) followed by a low pressure turbine stage consisting of a turning mid turbine frame and a counter-rotating LP-rotor. Downstream of the low pressure turbine a measurement section is instrumented with acoustic sensors. The acquisition system consists of a fully circumferentially traversable microphone array located at the outer casing, while at the hub endwall a stationary flush mounted microphone is placed as a reference. Additionally a new embedded concept for the turning mid turbine frame was tested. Here, two zero-lift splitters were located into the vane passage. In order to evaluate the noise emission of the turbine the facility was instrumented with a new acoustic measurement setup which is presented in the paper. Therefore the emitted sound pressure level and the microphones signal spectra are compared for both configurations. The acoustic field was characterized by azimuthal modes by means of a microphone array traversed over 360 degrees. In the multisplitter configuration, the propagating modes due to the HP turbine are found suppressed by 5 dB, while the increase in amplitude of the modes related to the LP turbine is negligible. The overall effect is a reduction of the acoustic emission for the turning mid turbine frame with embedded design.

Turbine Noise Reduction: Axial Spacing and Embedded Design

2015 ◽  
Author(s):  
C. Faustmann ◽  
S. Zerobin ◽  
S. Bauinger ◽  
A. Marn ◽  
F. Heitmeir ◽  
...  
Keyword(s):  
Power Level ◽  
Low Pressure ◽  
Sound Power ◽  
Noise Generation ◽  
Turbine Stage ◽  
Noise Emission ◽  
Low Pressure Turbine ◽  
Sound Power Level ◽  
Embedded Design ◽  
Lp Turbine

This paper deals with the investigation on the acoustics of different turning mid turbine frames (TMTF) in the two-stage two-spool test turbine located at the Institute for Thermal Turbomachinery and Machine Dynamics (ITTM) of Graz University of Technology. The facility is a continuously operating cold-flow open-circuit plant which is driven by pressurized air. The flow path consists of a transonic turbine stage (HP) followed by a low pressure turbine stage made of a turning mid turbine frame (TMTF) and a counter-rotating low pressure rotor. Downstream of the low pressure turbine a measurement section is instrumented with acoustic sensors. Three TMTF setups have been investigated at engine like flow conditions. The first configuration (C1) consists of 16 highly 3D-shaped turning struts. The goal of the second design (C2) was to reduce the length of the TMTF by 10% without increasing the losses and providing comparable inflow to the LP turbine rotor. This was achieved by applying 3D-contoured endwalls at the hub. The third one (C3) is a new embedded concept for the turning mid turbine frame with two zero-lift splitters placed into the strut passages. In total 48 vanes (16 struts plus 32 splitter vanes) guide the flow from the HP rotor to the LP rotor. The comparison in terms of noise generation and propagation of the turbines is done by the microphones signal spectra, the emitted sound pressure and sound power level of each TMTF setup. Therefore the acoustic field is characterized by azimuthal and radial modes by means of a microphone array at the outer casing traversed over 360 degrees. By comparing the first two setups (C1 and C2) in terms of noise generation the propagating modes due to the HP turbine were found to be the same, while a difference of 5 dB in amplitude of the modes related to the LP turbine was found due to the different axial spacing between both setups. In the multi-splitter configuration (C3), the overall sound power level depending on the blade passing frequency (BPF) of the HP turbine is reduced by 7 dB and depending on the BPF of the LP turbine by 4 dB compared to C1, respectively. The overall effect is a reduction of the noise emission for the HP turbine due to the embedded design as well as for the LP turbine due to increasing the axial spacing between the TMTF Vanes and LP Blades on the one hand and considerably due to the embedded design on the other hand.

Aerodynamics and Acoustics of Turning Mid Turbine Frames in a Two-Shaft Test Turbine

2014 ◽  
Author(s):  
C. Faustmann ◽  
E. Göttlich
Keyword(s):  
Pressure Loss ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Open Circuit ◽  
Point Of View ◽  
Turbine Stage ◽  
Cold Flow ◽  
Low Pressure Turbine ◽  
University Of Technology ◽  
Lp Turbine

The paper deals with the investigation on the aerodynamics and the acoustics of two different turning mid turbine frames (TMTF) in the two-stage two-spool test turbine located at the Institute for Thermal Turbomachinery and Machine Dynamics (ITTM) of Graz University of Technology. The facility is a continuously operating cold-flow open-circuit plant which is driven by pressurized air. The flow path consists of a transonic turbine stage (HP) followed by a low pressure turbine stage made of a turning mid turbine frame (TMTF) and a counter-rotating low pressure rotor. The two TMTF setups have been investigated at engine like flow conditions. The first configuration consists of 16 highly 3D-shaped turning struts. The goal of the second design was to reduce the length of the TMTF by 10% without increasing the losses and providing comparable inflow to the LP turbine rotor. This was achieved by applying 3D-contoured endwalls at the hub. To estimate the pressure loss over the duct aerodynamic measurements are performed at the inlet and the outlet of both turning mid turbine frames by using 5-hole probes (FHP) and total pressure rakes. The FHP-measurements at the inlet of the TMTF were performed in three different ways to obtain the influence of probe positioning and traversing on the results. While the 5-hole probe was traversed only in a sector the rakes were traversed over the full circumference. The comparison between the two turning mid turbine frame setups shows from an aerodynamic point of view that it is possible to reduce the engine weight by designing a 10% shorter TMTF with endwall contouring providing the same pressure loss and comparable inflow conditions for the LP turbine rotor. Due to the fact that noise becomes more and more an issue additional acoustic measurements were carried out downstream of the low pressure turbine. By comparing the two setups in terms of noise generation the propagating modes due to the HP turbine were found to be the same, while an increase of 10dB in amplitude of the modes related to the LP turbine was found in the 10% shorter setup. This is in good accordance with previous studies, where reducing the distance between stator and rotor increases the emitted sound.

Redesign of High-Lift LP-Turbine Airfoils for Low Speed Testing

2010 ◽  
Author(s):  
Michele Marconcini ◽  
Filippo Rubechini ◽  
Roberto Pacciani ◽  
Andrea Arnone ◽  
Francesco Bertini
Keyword(s):  
Separated Flow ◽  
Low Pressure ◽  
High Lift ◽  
Low Speed ◽  
Low Pressure Turbine ◽  
Wide Range ◽  
Flow Configurations ◽  
Artificial Neural Network Ann ◽  
Lp Turbine ◽  
Turbine Airfoils

Low pressure turbine airfoils of the present generation usually operate at subsonic conditions, with exit Mach numbers of about 0.6. To reduce the costs of experimental programs it can be convenient to carry out measurements in low speed tunnels in order to determine the cascades performance. Generally speaking, low speed tests are usually carried out on airfoils with modified shape, in order to compensate for the effects of compressibility. A scaling procedure for high-lift, low pressure turbine airfoils to be studied in low speed conditions is presented and discussed. The proposed procedure is based on the matching of a prescribed blade load distribution between the low speed airfoil and the actual one. Such a requirement is fulfilled via an Artificial Neural Network (ANN) methodology and a detailed parameterization of the airfoil. A RANS solver is used to guide the redesign process. The comparison between high and low speed profiles is carried out, over a wide range of Reynolds numbers, by using a novel three-equation, transition-sensitive, turbulence model. Such a model is based on the coupling of an additional transport equation for the so-called laminar kinetic energy (LKE) with the Wilcox k–ω model and it has proven to be effective for transitional, separated-flow configurations of high-lift cascade flows.

Experimental Study on the Effect of Clocking on the Propagation of Inflow Pressure Distortions in a Low Pressure Turbine Stage

2020 ◽  
Author(s):  
L. Simonassi ◽  
M. Zenz ◽  
P. Bruckner ◽  
S. Pramstrahler ◽  
F. Heitmeir ◽  
...  
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
Total Pressure ◽  
Low Pressure ◽  
Vibration Characteristics ◽  
Test Facility ◽  
Turbine Stage ◽  
Rotor Vibration ◽  
Low Pressure Turbine ◽  
The Impact

Abstract The design of modern aero engines enhances the interaction between components and facilitates the propagation of circumferential distortions of total pressure and temperature. As a consequence, the inlet conditions of a real turbine have significant spatial non-uniformities, which have direct consequences on both its aerodynamic and vibration characteristics. This work presents the results of an experimental study on the effects of different inlet total pressure distortion-stator clocking positions on the propagation of total pressure inflow disturbances through a low pressure turbine stage, with a particular focus on both the aerodynamic and aeroelastic performance. Measurements at a stable engine relevant operating condition and during transient operation were carried out in a one and a half stage subsonic turbine test facility at the Institute of Thermal Turbomachinery and Machine Dynamics at Graz University of Technology. A localised total pressure distortion was generated upstream of the stage in three different azimuthal positions relative to the stator vanes. The locations were chosen in order to align the distortion directly with a vane leading edge, suction side and pressure side. Additionally, a setup with clean inflow was used as reference. Steady and unsteady aerodynamic measurements were taken downstream of the investigated stage by means of a five-hole-probe (5HP) and a fast response aerodynamic pressure probe (FRAPP) respectively. Strain gauges applied on different blades were used in combination with a telemetry system to acquire the rotor vibration data. The aerodynamic interactions between the stator and rotor rows and the circumferential perturbation were studied through the identification of the main structures constituting the flow field. This showed that the steady and unsteady alterations created by the distortion in the flow field lead to modifications of the rotor vibration characteristics. Moreover, the importance of the impact that the pressure distortion azimuthal position has on the LPT stage aerodynamics and vibrations was highlighted.

Aerodesign and Testing of an Aeromechanically Highly Loaded LP Turbine

2003 ◽  
Vol 128 (4) ◽  
pp. 643-649 ◽  
Author(s):  
F. J. Malzacher ◽  
J. Gier ◽  
F. Lippl
Keyword(s):  
High Speed ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Test Facility ◽  
Performance Measurements ◽  
Two Stage ◽  
Low Pressure Turbine ◽  
High Mach ◽  
Lp Turbine ◽  
Compact Geometry

Future turbo systems for aircraft engines need very compact geometry, low weight, and high efficiency components. The geared turbofan enables the engine designer to decouple the speed of the fan and the LP turbine to combine a low speed fan with a high speed LP turbine. The low pressure turbine is a key component for this concept. The technological challenge is very much driven by the very high low-spool speed. Resulting as well from high inlet temperatures, the LP turbine needs cooling of the first stage. A new MTU LPT concept for such a high speed turbine has been developed and tested in a turbine rig. The concept consists of a two-stage turbine for extremely high speed and high stage pressure ratio (ER 2.3). This leads to extra high mechanical loading and an exotic combination of high Mach numbers (transonic) and very low Reynolds numbers. In this paper some design features are described. Some elements of the airfoil design were also tested in additional cascade tests. The two-stage turbine was tested at the Altitude Test Facility of the ILA, Stuttgart. The test setup is described including details of the instrumentation. Test data shows a good turbine performance. Measurements are also compared to 3D CFD, which is used to analyze local effects.

The Effect of Rotor Tip Clearance Size Onto the Separated Flow Through a Super-Aggressive S-Shaped Intermediate Turbine Duct Downstream of a Transonic Turbine Stage

2009 ◽  
Author(s):  
A. Marn ◽  
E. Go¨ttlich ◽  
F. Malzacher ◽  
H. P. Pirker
Keyword(s):  
Low Pressure ◽  
Tip Clearance ◽  
Flow Visualisation ◽  
Turbine Stage ◽  
Intermediate Turbine Duct ◽  
Low Pressure Turbine ◽  
Oil Flow ◽  
Blade Tip ◽  
Flow Through ◽  
Aero Engines

The demand of further increased bypass ratio of aero engines will lead to low pressure turbines with larger diameters, which rotate at lower speed. Therefore, it is necessary to guide the flow leaving the high pressure turbine to the low pressure turbine at a larger diameter without any loss generating separation or flow disturbances. Due to costs and weight this intermediate turbine duct (ITD) has to be as short as possible. This leads to an aggressive (high diffusion) and further to a super-aggressive s-shaped duct geometry. In order to investigate the influence of the blade tip gap size on such a high diffusion duct flow a detailed test arrangement under engine representative conditions is necessary. Therefore, the continuously operating Transonic Test Turbine Facility (TTTF) at Graz University of Technology has been adapted: An super-aggressive intermediate duct is arranged downstream of a transonic HP-turbine stage providing an exit Mach number of about 0.6 and a swirl angle of −15 degrees. A second LP-vane row is located at the end of the duct and represents the counter rotating low pressure turbine at a larger diameter. A following deswirler and a diffuser are the connection to the exhaust casing of the facility. In order to determine the influence of the blade tip gap size on the flow through such a super-aggressive s-shaped turbine duct measurements were conducted with two different tip gap sizes, 1.5% span (0.8 mm) and 2.4% span (1.3 mm). The aerodynamic design of the HP-turbine stage, ITD, LP-vane and the de-swirler was done by MTU Aero engines. In 2007 at ASME Turbo Expo the influence of the rotor clearance size onto the flow through an aggressive ITD was presented. For the present investigation this aggressive duct has been further shortened by 20% (super-aggressive ITD) that the flow at the outer duct wall is fully separated. This paper shows the influence of the rotor tip clearance size onto this separation. The flow through this intermediate turbine duct was investigated by means of five-hole-probes, static pressure taps, boundary layer rakes and oil flow visualisation. The oil flow visualisation showed the existence of vortical structures within the separation where they seem to be imposed by the upstream HP-vanes. This work is part of the EU-project AIDA (Aggressive Intermediate Duct Aerodynamics, Contract: AST3-CT-2003-502836).

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