Computational Investigation of Secondary Flow Structures in Low Pressure Turbines

2017 ◽  
Author(s):  
Jacob Sharpe ◽  
Philip Bear ◽  
Mitch Wolff ◽  
Christopher Marks ◽  
Rolf Sondergaard
Keyword(s):  
Secondary Flow ◽  
Low Pressure ◽  
Flow Structures ◽  
Computational Investigation

Experimental and Numerical Investigation of Secondary Flow Structures in an Annular Low Pressure Turbine Cascade Under Periodic Wake Impact—Part 2: Numerical Results

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Benjamin Winhart ◽  
Martin Sinkwitz ◽  
Andreas Schramm ◽  
David Engelmann ◽  
Francesca di Mare ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Direct Interaction ◽  
Numerical Data ◽  
Horseshoe Vortex ◽  
Low Pressure ◽  
Navier Stokes ◽  
Flow Structures ◽  
Pressure Loss Coefficient ◽  
Low Pressure Turbine ◽  
Numerical Predictions

In this work, we present the results of the numerical investigations of periodic wake–secondary flow interaction carried out on a low pressure turbine (LPT) equipped with modified T106-profile blades. The numerical predictions obtained by means of unsteady Reynolds-averaged Navier–Stokes (URANS) simulations using a k-ω-model have been compared with measurements conducted in the same configuration and showed a good agreement. Based on the verified numerical data, the Q-criterion has been employed to characterize the secondary flow structures and accurately identify their origin. An analysis of the fundamental wake kinematics and the unsteady vortex migration revealed dominant interaction mechanisms such as the circumferential fluctuation of the pressure side horseshoe vortex (HSV) and its direct interaction with the passage vortex (PV) and the concentrated shed vortex (CSV). Finally, a correlation with the total pressure loss coefficient is provided and a link to the incoming wake structures is given.

The Effect of Profile Contouring on Secondary Flow Structures in Low Pressure Turbines

2016 ◽  
Author(s):  
Philip S. Bear ◽  
Mitch Wolff ◽  
Christopher R. Marks ◽  
Rolf Sondergaard
Keyword(s):  
Secondary Flow ◽  
Low Pressure ◽  
Flow Structures

On the Unsteady Formation of Secondary Flow Inside a Rotating Turbine Blade Passage

2013 ◽  
Vol 136 (6) ◽  
Author(s):  
C. M. Schneider ◽  
D. Schrack ◽  
M. Kuerner ◽  
M. G. Rose ◽  
S. Staudacher ◽  
...  
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Guide Vane ◽  
Low Pressure ◽  
Flow Structures ◽  
Low Pressure Turbine ◽  
Interaction Processes ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Secondary Flow Field

This paper addresses the unsteady formation of secondary flow structures inside a turbine rotor passage. The first stage of a two-stage, low-pressure turbine is investigated at a Reynolds Number of 75,000. The design represents the third and the fourth stages of an engine-representative, low-pressure turbine. The flow field inside the rotor passage is discussed in the relative frame of reference using the streamwise vorticity. A multistage unsteady Reynolds-averaged Navier–Stokes (URANS) prediction provides the time-resolved data set required. It is supported by steady and unsteady area traverse data acquired with five-hole probes and dual-film probes at rotor inlet and exit. The unsteady analysis reveals a nonclassical secondary flow field inside the rotor passage of this turbine. The secondary flow field is dominated by flow structures related to the upstream nozzle guide vane. The interaction processes at hub and casing appear to be mirror images and have characteristic forms in time and space. Distinct loss zones are identified, which are associated with vane-rotor interaction processes. The distribution of the measured isentropic stage efficiency at rotor exit is shown, which is reduced significantly by the secondary flow structures discussed. Their impacts on the steady as well as on the unsteady angle characteristics at rotor exit are presented to address the influences on the inlet conditions of the downstream nozzle guide vane. It is concluded that URANS should improve the optimization of rotor geometry and rotor loss can be controlled, to a degree, by nozzle guide vane (NGV) design.

Impact of Varying High- and Low-Pressure Turbine Purge Flows on a Turbine Center Frame and Low-Pressure Turbine System

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
P. Z. Sterzinger ◽  
S. Zerobin ◽  
F. Merli ◽  
L. Wiesinger ◽  
A. Peters ◽  
...  
Keyword(s):  
High Pressure ◽  
Secondary Flow ◽  
Low Pressure ◽  
Flow Structures ◽  
Flow Conditions ◽  
High Pressure Turbine ◽  
Inlet Flow ◽  
Low Pressure Turbine ◽  
The Impact ◽  
Inflow Conditions

Abstract This paper presents the experimental and numerical evaluation and comparison of the different flow fields downstream of a turbine center frame duct and a low-pressure turbine (LPT) stage, generated by varying the inlet flow conditions to the turbine center frame (TCF) duct. The measurements were carried out in an engine-representative two-stage two-spool test turbine facility at the Institute for Thermal Turbomachinery and Machine Dynamics at Graz University of Technology. The rig consists of a high-pressure turbine (HPT) and a LPT turbine stage, connected via a TCF with non-turning struts. Four individual high-pressure turbine purge flowrates and two low-pressure turbine purge flowrates were varied to achieve different engine-relevant TCF and LPT inlet flow conditions. The experimental data were acquired by means of five-hole-probe (5HP) area traverses upstream and downstream of the TCF and downstream of the LPT. A steady Reynolds-averaged Navier–Stokes (RANS) simulation taking all purge flows in account was used for comparison, and additional insights are gained from a numerical variation of the HPT and LPT purge flowrates. The focus of this study is on the impact of the variations in TCF inlet conditions on the secondary flow generation through the TCF duct and the carryover effects on the exit flow field and performance of the LPT stage. Existing work is limited by either investigating multistage LPT configurations with generally very few measurements behind the first stage or by not including relevant HPT secondary flow structures in setting up the LPT inflow conditions. This work addresses both of these shortcomings and presents new insight into the TCF and LPT aerodynamic behavior at varying the HPT and LPT purge flows. The results demonstrate the importance of the HPT flow structures and their evolution through the TCF duct for setting up the LPT inflow conditions and ultimately for assessing the performance of the first LPT stage.

Impact of Varying High- and Low-Pressure Turbine Purge Flows on a Turbine Center Frame and Low-Pressure Turbine System

2019 ◽  
Author(s):  
P. Z. Sterzinger ◽  
S. Zerobin ◽  
F. Merli ◽  
L. Wiesinger ◽  
A. Peters ◽  
...  
Keyword(s):  
High Pressure ◽  
Secondary Flow ◽  
Low Pressure ◽  
Flow Structures ◽  
Turbine Stage ◽  
Flow Conditions ◽  
Flow Rates ◽  
Low Pressure Turbine ◽  
Purge Flow ◽  
Inflow Conditions

Abstract This paper presents the experimental and numerical evaluation and comparison of the different flow fields downstream of a turbine center frame duct and a low-pressure turbine stage, generated by varying the inlet flow conditions to the turbine center frame duct. The measurements were carried out in an engine-representative two-stage two-spool test turbine facility at the Institute for Thermal Turbomachinery and Machine Dynamics at Graz University of Technology. The rig consists of a high-pressure (HPT) and a low-pressure (LPT) turbine stage, connected via a turbine center frame (TCF) with non-turning struts. Four individual high-pressure turbine purge flow rates and two low-pressure turbine purge flow rates were varied to achieve different engine-relevant TCF and LPT inlet flow conditions. The experimental data was acquired by means of five-hole-probe area traverses upstream and downstream of the TCF, and downstream of the LPT. A steady RANS simulation taking all purge flows in account was used for comparison and additional insight are gained from a numerical variation of the HPT and LPT purge flow rates. The focus of this study is on the impact of the variations in TCF inlet conditions on the secondary flow generation through the TCF duct and the carry-over effects on the exit flow field and performance of the LPT stage. Existing work is limited by either investigating multi-stage LPT configurations with generally very few measurements behind the first stage or by not including relevant HPT secondary flow structures in setting up the LPT inflow conditions. This work addresses both of these shortcomings and presents new insight into the TCF and LPT aerodynamic behavior at varying the HPT and LPT purge flows. The results demonstrate the importance of the HPT flow structures and their evolution through the TCF duct for setting up the LPT inflow conditions, and ultimately for assessing the performance of the first LPT stage.

On the Unsteady Formation of Secondary Flow Inside a Rotating Turbine Blade Passage

2013 ◽  
Author(s):  
C. M. Schneider ◽  
D. Schrack ◽  
M. Kuerner ◽  
M. G. Rose ◽  
S. Staudacher ◽  
...  
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Guide Vane ◽  
Low Pressure ◽  
Flow Structures ◽  
Low Pressure Turbine ◽  
Interaction Processes ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Secondary Flow Field

This paper addresses the unsteady formation of secondary flow structures inside a turbine rotor passage. The first stage of a two-stage low pressure turbine is investigated at a Reynolds Number of 75 000. The design represents the third and the fourth stages of an engine representative low pressure turbine. The flow field inside the rotor passage is discussed in the relative frame of reference using the streamwise vorticity. A multi-stage URANS prediction provides the time-resolved data set required. It is supported by steady and unsteady area traverse data acquired with five-hole probes and dual-film probes at rotor inlet and exit. The unsteady analysis reveals a non-classical secondary flow field inside the rotor passage of this turbine. The secondary flow field is dominated by flow structures related to the upstream nozzle guide vane. The interaction processes at hub and casing appear to be mirror images and have characteristic forms in time and space. Distinct loss zones are identified which are associated with vane-rotor interaction processes. The distribution of the measured isentropic stage efficiency at rotor exit is shown which is reduced significantly by the secondary flow structures discussed. Their impacts on the steady as well as on the unsteady angle characteristics at rotor exit are presented to address the influences on the inlet conditions of the downstream nozzle guide vane.

Influence of Hot Streak Temperature Ratio on Low Pressure Stage of a Vaneless Counter-Rotating Turbine

2007 ◽  
Author(s):  
Qingjun Zhao ◽  
Fei Tang ◽  
Huishe Wang ◽  
Jianyi Du ◽  
Xiaolu Zhao ◽  
...  
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Secondary Flow ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Temperature Ratio ◽  
High Pressure Turbine ◽  
Pressure Stage ◽  
Low Pressure Turbine ◽  
Hot Streak

In order to explore the influence of hot streak temperature ratio on low pressure stage of a Vaneless Counter-Rotating Turbine, three-dimensional multiblade row unsteady Navier-Stokes simulations have been performed. The predicted results show that hot streaks are not mixed out by the time they reach the exit of the high pressure turbine rotor. The separation of colder and hotter fluids is observed at the inlet of the low pressure turbine rotor. After making interactions with the inner-extending shock wave and outer-extending shock wave in the high pressure turbine rotor, the hotter fluid migrates towards the pressure surface of the low pressure turbine rotor, and the most of colder fluid migrates to the suction surface of the low pressure turbine rotor. The migrating characteristics of the hot streaks are predominated by the secondary flow in the low pressure turbine rotor. The effect of buoyancy on the hotter fluid is very weak in the low pressure turbine rotor. The results also indicate that the secondary flow intensifies in the low pressure turbine rotor when the hot streak temperature ratio is increased. The effects of the hot streak temperature ratio on the relative Mach number and the relative flow angle at the inlet of the low pressure turbine rotor are very remarkable. The isentropic efficiency of the Vaneless Counter-Rotating Turbine decreases as the hot streak temperature ratio is increased.

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