scholarly journals Clocking of stators in one and half stage of axial steam turbine

2018 ◽  
Vol 180 ◽  
pp. 02071
Author(s):  
Martin Němec ◽  
Tomáš Jelínek ◽  
Petr Milčák
Keyword(s):  
Flow Field ◽  
Velocity Ratio ◽  
Flow Analysis ◽  
Fast Response ◽  
Detailed Measurement ◽  
Outlet Flow ◽  
Response Pressure ◽  
The Impact ◽  
Unsteady Flow Analysis ◽  
Flow Field Measurement

An investigation of one and half axial turbine stage configuration was carried out in a closed-loop wind tunnel. The investigation was addressed to that impact how the previous stage outlet flow field influences the flow structures in the next stator in steam multistage turbines. The stage - stator interaction has been studied in this work. The detailed measurement with a pneumatic probes and fast response pressure probes behind the rotor and the second stator were performed to gain the useful data to analyze the impact. The detailed flow field measurement was carried out in the nominal stage regime (given by the stage isentropic Mach number 0.3 and velocity ratio u/c 0.68). The clocking effect of the stators is discussed and detailed unsteady flow analysis is shown.

Unsteady Flow Analysis and Vibratory Stress Predictions for a High Work Single Stage Turbine Blade

2012 ◽  
Author(s):  
Kurt Weber ◽  
Girish Modgil ◽  
Steve Gegg ◽  
Shyam Neerarambam ◽  
Moujin Zhang
Keyword(s):  
Flow Field ◽  
Strain Gauge ◽  
Flow Analysis ◽  
Forced Response ◽  
Single Stage ◽  
Turbine Stage ◽  
Rotating Blade ◽  
Gauge Data ◽  
Unsteady Flow Analysis ◽  
High Work

The flow field in High-Work Single-Stage (HWSS) turbines differs from traditional turbine flow fields. Operating at increased pressure ratios, wakes and trailing edge shocks at the exit of the vane are more likely to cause a vibratory response in the rotating blade. This flow field can produce increased excitation at harmonics that correspond to the vane passing frequency and harmonics higher than the vane passing frequency. In this paper, blade vibratory stresses in a HWSS gas turbine stage are predicted using unsteady pressures from two Rolls-Royce in-house flow codes that employ different phase lagged unsteady approaches. Hydra uses a harmonic storage approach, and the Vane/Blade Interaction (VBI) code uses a direct storage approach. Harmonic storage reduces memory requirements considerably. The predicted stress for four modes at two engine speeds are presented and are compared with rig test strain gauge data to assess and validate the predictive capability of the codes for forced response. Strain gauge data showed the need to consider harmonics higher than the fundamental vane passing frequency for the max power shaft speed and operating at the conditions. Because of this, it was a good case for validation and for comparing the two codes. Overall, it was found that, stress predictions using the Hydra flow code compare better with data. To the best of the authors’ knowledge, this paper is a first in comparing two different phase lagged unsteady approaches, in the context of forced response, to engine rig data for a High-Work Single Stage turbine.

Experimental Investigation of Steady and Unsteady Flow Field Downstream of an Automotive Torque Converter Turbine and Inside the Stator: Part II—Unsteady Pressure on the Stator Blade Surface

1997 ◽  
Vol 119 (3) ◽  
pp. 634-645 ◽  
Author(s):  
B. V. Marathe ◽  
B. Lakshminarayana ◽  
D. G. Maddock
Keyword(s):  
Flow Field ◽  
Leading Edge ◽  
Torque Converter ◽  
Fast Response ◽  
Ensemble Averaging ◽  
Pressure Transducers ◽  
Stator Blade ◽  
Response Pressure ◽  
Aperiodic Component ◽  
Upstream Flow

The stator flow field of an automotive torque converter is highly unsteady due to potential and viscous interactions with upstream and downstream rotors. The objective of this investigation is to understand the influence of potential and viscous interactions of the upstream rotor on the stator surface pressure field with a view toward improvement of the stator design. Five miniature fast-response pressure transducers were embedded on the stator blade. The measurements were conducted at three locations near the leading edge and two locations near the trailing edge at the midspan location. The upstream flow field was measured using a fast response five-hole probe and is described in Part I of this paper. The experimental data were processed in the frequency domain by spectrum analysis and in the temporal-spatial domain by the ensemble-averaging technique. The flow properties were resolved into mean, periodic, aperiodic, and unresolved components. The unsteady amplitudes agreed well with the pressure envelope predicted by panel methods. The aperiodic component was found to be significant due to the rotor–rotor and rotor–stator interactions observed in multistage, multispool environment.

scholarly journals Experimental Investigation of Steady and Unsteady Flow Field Downstream of an Automotive Torque Converter Turbine and Inside the Stator: Part II — Unsteady Pressure on the Stator Blade Surface

1995 ◽  
Author(s):  
B. V. Marathe ◽  
B. Lakshminarayana ◽  
Donald G. Maddock
Keyword(s):  
Flow Field ◽  
Leading Edge ◽  
Torque Converter ◽  
Fast Response ◽  
Ensemble Averaging ◽  
Pressure Transducers ◽  
Stator Blade ◽  
Response Pressure ◽  
Aperiodic Component ◽  
Upstream Flow

The stator flow field of an automotive torque converter is highly unsteady due to potential and viscous interactions with upstream and downstream rotors. The objective of this investigation is to understand the influence of potential and viscous interactions of the upstream rotor on the stator surface pressure field with a view towards improvement of the stator design. Five miniature fast-response pressure transducers were embedded on the stator blade. The measurements were conducted at three locations near the leading edge and two locations near the trailing edge at the mid-span location. Upstream flow field was measured using a fast response five-hole probe and is described in the first part of this paper. The experimental data were processed in the frequency domain by spectrum analysis and in temporal-spatial domain by the ensemble averaging technique. The flow properties were resolved into mean, periodic, aperiodic and unresolved components. The unsteady amplitudes agreed well with the pressure envelope predicted by panel methods. Aperiodic component was found to be significant due to the rotor-rotor and rotor-stator interactions observed in multistage, multi-spool environment.

Investigation of 3D Unsteady Flows in a Two Stage Shrouded Axial Turbine Using Stereoscopic PIV and FRAP: Part I — Interstage Flow Interactions

2006 ◽  
Author(s):  
L. Porreca ◽  
Y. I. Yun ◽  
A. I. Kalfas ◽  
S. J. Song ◽  
R. S. Abhari
Keyword(s):  
Flow Field ◽  
Measurement Techniques ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Fast Response ◽  
Design Flow ◽  
Main Stream ◽  
Two Stage ◽  
Axial Turbine ◽  
Improved Design

A detailed flow analysis has been carried out in a two-stage shrouded axial turbine by means of intrusive and non-intrusive measurement techniques. Multi-sensor Fast Response Aerodynamic Probe (FRAP) and 3D-PIV system were applied at two locations downstream of the first and second rotors. Several radial planes were measured focusing on the blade tip region in order to obtain a unique set of steady and unsteady velocity data. The investigation deals with the aerodynamics and kinematics of flow structures downstream of the first and second rotors and their interaction with the main flow in a partially shrouded turbine typical of industrial application. The first part of this work is focused on the flow field downstream of the first rotor while the second part studies the leakage flow in the cavity of the second rotor and its interaction with the main stream. The interstage region is characterized by interactions between the tip passage vortex and a vortex caused by the recessed shroud platform design. Flow coming from the blade passage suddenly expands and migrates radially in the cavity region causing a localized total pressure drop. The time evolution of these vortical structures and the associated downstream unsteady loss generation are analyzed. The partial shroud design adopted in this geometry is beneficial in terms of blade stress and thermal load; however flow field downstream of the first rotor is highly three dimensional due to the intense interaction between cavity and main streams. A flow interpretation is provided and suggestions for improved design are finally addressed based on the steady and unsteady flow analysis.

Investigation of Unsteady Compressor Flow Structure With Tip Injection Using Particle Image Velocimetry

2011 ◽  
Author(s):  
Roland Matzgeller ◽  
Melanie Voges ◽  
Michael Schroll
Keyword(s):  
Flow Field ◽  
Leading Edge ◽  
Fast Response ◽  
Rotating Stall ◽  
Fluid Injection ◽  
Pressure Transducers ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Response Pressure ◽  
Tip Injection

Fluid injection at the tip of highly loaded compressor rotors is known to be very effective in suppressing the onset of rotating stall and eventually compressor instability. To understand the effects of tip injection, the flow field at the tip region of a transonic compressor rotor with and without fluid injection was investigated in this paper. Using results acquired by phase-locked PIV measurements as well as the static pressure field obtained by fast response pressure transducers, the unsteady interaction between the injection jet and the rotor could be described thoroughly. Both, an influence of the rotor’s flow field on the jet as well of the jet on the rotor was clearly visible. Since unsteady inflow conditions to the front rotor in the relative frame of reference were imposed by the injection jets, the rotor’s unsteady response was investigated by inspection of the position of the tip leakage vortex trajectory. It could be shown that due to a short time for the flow to adapt at the rotor’s leading edge, its position didn’t change distinctly. Because a significantly longer time was needed for the overall passage flow to adapt, it was concluded that this causes the beneficial effect of tip injection.

Identification of Spinning Mode in the Unsteady Flow Field of a LP Turbine

2011 ◽  
Author(s):  
Davide Lengani ◽  
Berardo Paradiso ◽  
Andreas Marn ◽  
Emil Go¨ttlich
Keyword(s):  
Flow Field ◽  
Guide Vane ◽  
Fast Response ◽  
Turbine Rotor ◽  
Pressure Probe ◽  
Model Parameters ◽  
Time Resolved ◽  
Flow Angle ◽  
Response Pressure ◽  
Lp Turbine

This paper presents an experimental investigation of the vane-blade unsteady interaction in an unshrouded LP turbine research rig with uneven blade/vane count (72 blades and 96 vanes). The rig was designed in cooperation with MTU Aero Engines and considerable efforts were put on the adjustment of all relevant model parameters. In particular blade count ratio, airfoil aspect ratio, reduced massflow, reduced speed, Mach and Reynolds numbers were chosen to reproduce the full scale LP turbine at take off condition. Measurements by means of a fast-response pressure probe were performed adopting a phase-locked acquisition technique in order to provide the time resolved flow field downstream of the turbine rotor. The probe has been fully traversed both in circumferential and radial traverses. The rotor exit is characterized by strong perturbations due to the tip leakage vortex and the rotor blade wake. Circumferential non uniformities due to the upstream vane wake and to the downstream exit guide vane potential effects are also identified. Furthermore in the present configuration with an uneven blade/vane count the non-uniformities due to the stator and rotor row are misaligned along the whole turbine circumference and create a spinning mode that rotates in direction opposite to the rotor at a high frequency. The aeroacoustic theory is employed to explain such further unsteady pattern. The variations of the exit flow angle within a cycle of such pattern are not negligible and almost comparable to the ones within the blade passing period.

Impact of Turbine-Strut Clocking on the Performance of a Turbine Center Frame

2020 ◽  
Author(s):  
P. Z. Sterzinger ◽  
F. Merli ◽  
A. Peters ◽  
S. Behre ◽  
F. Heitmeir ◽  
...  
Keyword(s):  
Flow Field ◽  
Numerical Data ◽  
Fast Response ◽  
Pressure Probe ◽  
Performance Impact ◽  
Aerodynamic Pressure ◽  
Carry Over ◽  
Vane Clocking ◽  
The Individual ◽  
The Impact

Abstract Previous studies have indicated a potential for improving the performance of a Turbine Center Frame (TCF) duct by optimizing the clocking position between the high-pressure-turbine (HPT) vanes and TCF struts. To assess the impact of clocking on the performance, a new test vehicle with a clockable ratio of HPT vanes to TCF struts, consisting of an HPT stage (aero-dynamically representative of the second-stage HPT engine), a TCF duct with non-turning struts, and a first-stage low-pressure turbine vane, was designed and tested in the transonic test turbine facility (TTTF) at Graz University of Technology. This paper quantifies the performance impact of clocking and describes the mechanisms causing TCF flow field changes, leveraging both experimental and numerical data. Other areas in the TCF duct impacted by the choice of the HPT vane circumferential position including the strength of unsteady HPT-TCF interaction modes, TCF strut incidence changes, and carry-over effects to the first LPT vane are additionally highlighted. Five-hole-probe (5HP) area traverses and kielhead-rake traverses were used to asses the flow field at the TCF-exit and calculate the pressure loss. The flow field at the TCF exit shows significant differences depending on the circumferential position of the HPT vane. A relative performance benefit of 5% was achieved. A series of unsteady RANS simulations were performed to support the measured results, understand and characterize the relevant loss mechanisms. The observed performance improvement was related to interaction between the HPT secondary -flow structures and the TCF struts. The impact of the HPT vane clocking on the unsteady flow field downstream of the TCF was investigated using Fast-Response Aerodynamic Pressure Probe (FRAPP) area traverses, analyzed by means of modal decomposition. In this way the individual azimuthal modes were ranked by their amplitude and a dependency of the clocking position was observed and quantified.

Casing Pressure Measurements and Numerical Simulations of a 1.5 Stage Axial Compressor: Tip Leakage Flow and Rotating Instability

2014 ◽  
Author(s):  
Hao Wang ◽  
Yadong Wu ◽  
Hua Ouyang ◽  
Jie Tian ◽  
Zhaohui Du
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Axial Compressor ◽  
Fast Response ◽  
Tip Leakage Flow ◽  
Tip Leakage Vortex ◽  
Pressure Transducers ◽  
Tip Leakage ◽  
Response Pressure ◽  
Rotating Instability

Experimental and numerical investigations on the unsteady casing flow field in a one-and-half stage low speed axial compressor have been carried out. By using fast response pressure transducers instrumented on the rotor casing, the pressure time series were acquired at different operation points from throttle wide open to near-stall operation point. The pseudo-spatial pressure contours, phase-locked averaged and root-mean-square pressure contours and power spectrums of unsteady pressure signal have been achieved. The CFD simulations were conducted to help understanding the features of tip leakage vortex. The rotating instability has been detected throughout an operation range from small flow rate point to near stall point. The frequency characteristic of rotating instability according flow rate was discussed. Based on the pattern of RIF varying with flow rate, the developing process of rotating instability according to flow rate could be divided into two stages, referred as early-developing stage and fully-developed stage. By analyzing the correlation between rotating instability and casing flow field, it was discovered that the origination and development of rotating instability was closely related to the fluctuation induced by tip leakage vortex.

scholarly journals Impact of Powder Properties on the Rheological Behavior of Excipients

Pharmaceutics ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1198
Author(s):  
Pauline H. M. Janssen ◽  
Sébastien Depaifve ◽  
Aurélien Neveu ◽  
Filip Francqui ◽  
Bastiaan H. J. Dickhoff
Keyword(s):  
Flow Field ◽  
Rheological Behavior ◽  
Quality By Design ◽  
Filling Process ◽  
Dynamic Flow ◽  
Die Filling ◽  
Flow Characterization ◽  
Wide Range ◽  
Powder Properties ◽  
The Impact

With the emergence of quality by design in the pharmaceutical industry, it becomes imperative to gain a deeper mechanistic understanding of factors impacting the flow of a formulation into tableting dies. Many flow characterization techniques are present, but so far only a few have shown to mimic the die filling process successfully. One of the challenges in mimicking the die filling process is the impact of rheological powder behavior as a result of differences in flow field in the feeding frame. In the current study, the rheological behavior was investigated for a wide range of excipients with a wide range of material properties. A new parameter for rheological behavior was introduced, which is a measure for the change in dynamic cohesive index upon changes in flow field. Particle size distribution was identified as a main contributing factor to the rheological behavior of powders. The presence of fines between larger particles turned out to reduce the rheological index, which the authors explain by improved particle separation at more dynamic flow fields. This study also revealed that obtained insights on rheological behavior can be used to optimize agitator settings in a tableting machine.

scholarly journals A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4136
Author(s):  
Clemens Gößnitzer ◽  
Shawn Givler
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Negative Impact ◽  
Operating Conditions ◽  
Engine Operation ◽  
Gas Engine ◽  
Cycle Simulation ◽  
Simulation Results ◽  
The Impact

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.

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