scholarly journals Unsteady Flow Field Due to Nozzle Wake Interaction With the Rotor in an Axial Flow Turbine: Part I—Rotor Passage Flow Field

1997 ◽  
Vol 119 (2) ◽  
pp. 201-213 ◽  
Author(s):  
M. A. Zaccaria ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Axial Flow ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Suction Surface ◽  
Pressure Surface ◽  
Aerodynamic Interaction ◽  
Flow Gradients ◽  
Rotor Flow

The flow field in turbine rotor passages is complex with unsteadiness caused by the aerodynamic interaction of the nozzle and rotor flow fields. The two-dimensional steady and unsteady flow field at midspan in an axial flow turbine rotor has been investigated experimentally using an LDV with emphasis on the interaction of the nozzle wake with the rotor flow field. The flow field in the rotor passage is presented in Part I. while the flow field downstream of the rotor is presented in Part II. Measurements were acquired at 37 axial locations from just upstream of the rotor to one chord downstream of the rotor. The time-averaged flow field and the unsteadiness caused by the wake have been captured. As the nozzle wake travels through the rotor flow field, the nozzle wake becomes distorted with the region of the nozzle wake near the rotor suction surface moving faster than the region near the rotor pressure surface, resulting in a highly distorted wake. The wake is found to be spread out along the rotor pressure surface, as it convects downstream of midchord. The magnitude of the nozzle wake velocity defect grows until close to midchord, after which it decreases. High values of unresolved unsteadiness were observed at the rotor leading edge. This is due to the large flow gradients near the leading edge and the interaction of the nozzle wake with the rotor leading edge. High values of unresolved unsteadiness were also observed near the rotor pressure surface. This increase in unresolved unsteadiness is caused by the interaction of the nozzle wake with the flow near the rotor pressure surface.

scholarly journals Unsteady Flow Field due to Nozzle Wake Interaction With the Rotor in an Axial Flow Turbine: Part I — Rotor Passage Flow Field

1995 ◽  
Author(s):  
Michael A. Zaccaria ◽  
Budugur Lakshminarayana
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Axial Flow ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Suction Surface ◽  
Pressure Surface ◽  
Aerodynamic Interaction ◽  
Flow Gradients ◽  
Rotor Flow

The flow field in turbine rotor passages is complex with unsteadiness caused by the aerodynamic interaction of the nozzle and rotor flow fields. The two-dimensional steady and unsteady flow field at midspan in an axial flow turbine rotor has been investigated experimentally using an LDV with emphasis on the interaction of the nozzle wake with the rotor flow field. The flow field in the rotor passage is presented in Part I, while the flow field downstream of the rotor is presented in Part II. Measurements were acquired at 37 axial locations from just upstream of the rotor to one chord downstream of the rotor. The time average flow field and the unsteadiness caused by the wake has been captured. As the nozzle wake travels through the rotor flow field, the nozzle wake becomes distorted with the region of the nozzle wake near the rotor suction surface moving faster than the region near the rotor pressure surface, resulting in a highly distorted wake. The wake is found to be spread out along the rotor pressure surface, as it convects downstream of midchord. The magnitude of the nozzle wake velocity defect grows until close to midchord, after which it decreases. High values of unresolved unsteadiness were observed at the rotor leading edge. This is due to the large flow gradients near the leading edge and the interaction of the nozzle wake with the rotor leading edge. High values of unresolved unsteadiness were also observed near the rotor pressure surface. This increase in unresolved unsteadiness is caused by the interaction of the nozzle wake with the flow near the rotor pressure surface.

scholarly journals Unsteady Flow Field Due to Nozzle Wake Interaction With the Rotor in an Axial Flow Turbine: Part II—Rotor Exit Flow Field

1997 ◽  
Vol 119 (2) ◽  
pp. 214-224 ◽  
Author(s):  
M. A. Zaccaria ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Velocity Component ◽  
Axial Flow ◽  
Turbine Rotor ◽  
Edge Region ◽  
Trailing Edge ◽  
Rotor Wake ◽  
Cross Correlations ◽  
Far Wake

The two-dimensional steady and unsteady flow field at midspan in a turbine rotor has been investigated experimentally using an LDV with an emphasis on the interaction of the nozzle wake with the rotor flow field. The velocity measurements are decomposed into a time-averaged velocity, a periodic velocity component, and an unresolved velocity component. The results in the rotor passage were presented in Part I. The flow field downstream of the rotor is presented in this paper. The rotor wake profiles and their decay characteristics were analyzed. Correlations are presented that match the decay of the various wake properties. The rotor wake velocity defect decays rapidly in the trailing edge region, becoming less rapid in the near and far wake regions. The rotor wake semi-wake width increases rapidly in the trailing edge region and then grows more gradually in the near and far wake regions. The decay of the maximum unresolved unsteadiness and maximum unresolved velocity cross correlations is very rapid in the trailing edge region and this trend slows in the far wake region. In the trailing edge region, the maximum periodic velocity correlations are much larger than the maximum unresolved velocity correlations. But the periodic velocity correlations decay much faster than the unresolved velocity correlations. The interactions of the nozzle and rotor wakes are also studied. While the interaction of the nozzle wake with the rotor wake does not influence the decay rate of the various wake properties, it does change the magnitude of the properties. These and other results are presented in this paper.

Visualizations of the Unsteady Flow Field Near the Endwall of a Compressor Cascade

2001 ◽  
Author(s):  
Hongwei Ma ◽  
Haokang Jiang ◽  
Lin Yang
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Cross Sections ◽  
Leading Edge ◽  
Light Sheet ◽  
Horseshoe Vortex ◽  
Radial Clearance ◽  
Compressor Cascade ◽  
Complex Flow ◽  
Suction Surface

This paper presents flow visualizations of the unsteady flow field near the endwall of a compressor cascade. The experiments were performed in a water tunnel using the hydrogen bubble technique. A Pt wire was positioned parallel to the endwall and ahead of the cascade at 2% span from the endwall. The traces of hydrogen bubbles generated by the wire were visualized within a light sheet arranged at various cross-sections around the cascade. The unsteady flow field was visualized at different incidences without a radial clearance. A periodically fluctuating horseshoe vortex system of varying number of vortices is observed near the leading edge of the cascade, which plays a leading role in the flow field near the endwall. The interaction and the flow mixing among the counter-rotating horseshoe legs, the endwall boundary layer and the main flow, periodically occur in the passage. Breakdown of the horseshoe vortex is clearly observed in the cascade while the unsteady and complex flow field is shown at the corner of the suction surface.

Unsteady Flow Field of an Axial-Flow Turbine Rotor at a Low Reynolds Number

2006 ◽  
Author(s):  
Takayuki Matsunuma
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Unsteady Flow ◽  
Low Reynolds Number ◽  
Axial Flow ◽  
Turbine Rotor ◽  
Frame Of Reference ◽  
Flow Angle ◽  
Low Reynolds ◽  
Secondary Vortices

The unsteady flow field of an annular turbine rotor was investigated experimentally using a laser Doppler velocimetry (LDV) system. Detailed measurements of the time-averaged and time-resolved distributions of the velocity, flow angle, and turbulence intensity, etc. were carried out at a very low Reynolds number condition, Reout = 3.5 × 104. The data obtained were analyzed from the viewpoints of both an absolute (stationary) frame of reference and a relative (rotating) frame of reference. The effect of the turbine nozzle wake and secondary vortices on the flow field inside the rotor passage was clearly captured. It was found that the nozzle wake and secondary vortices are suddenly distorted at the rotor inlet, because of the rotating potential field of the rotor. The nozzle flow (wake and passage vortices) and the rotor flow (boundary layer, wake, tip leakage vortex, and passage vortices) interact intensively inside the rotor passage.

Development of the Unsteady Flow on a Turbine Rotor Platform Downstream of a Rim Seal

2004 ◽  
Author(s):  
Kirk D. Gallier ◽  
Patrick B. Lawless ◽  
Sanford Fleeter
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Secondary Flows ◽  
Thermal Design ◽  
Flow Rates ◽  
Image Velocimetry ◽  
Downstream Flow

In high temperature turbines, air from disk cavities is forced through the vane-rotor seal to prevent hot gas ingress into these cavities. This emergent seal air can play a significant role in the formation of secondary flows which emanate from the hub region near the rotor blade leading edge. The formation of these structures is also dependent on the inherently unsteady flow field driven by the vane-rotor interaction. As these secondary flows play an important role in both blade performance and heat transfer, the physics that governs them is of significant interest in turbine aero and thermal design. This work investigates and characterizes the aerodynamic signature of the interaction between an emergent seal flow and the hub flow approaching the downstream rotor including the effects of vane-rotor interaction. This is accomplished by means of an experimental investigation performed on the first stage of the Purdue Research Turbine using Particle Image Velocimetry (PIV). The flow field is interrogated in the near-hub region of the intra-stage space, downstream of the first vane row. Purge air is introduced through a planar seal at two different flow rates which characterize typical high and low boundaries for the range of dimensionless seal flow rates encountered in practice. Two-dimensional (radial and axial) velocity data from four measurement planes spaced from vane pressure side to mid-passage are acquired. These data are phase-locked to rotor position. The ensemble-averaged vorticity data from each of ten rotor positions provide a characterization of the effect of the rotor potential field on the emergent seal flow. Vane wake affects on purge strength and downstream flow development are captured at each of two seal flow rates.

Unsteady Flow Field of an Axial-Flow Turbine Rotor at a Low Reynolds Number

2006 ◽  
Vol 129 (2) ◽  
pp. 360-371 ◽  
Author(s):  
Takayuki Matsunuma
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Unsteady Flow ◽  
Low Reynolds Number ◽  
Axial Flow ◽  
Turbine Rotor ◽  
Frame Of Reference ◽  
Flow Angle ◽  
Low Reynolds ◽  
Secondary Vortices

The unsteady flow field of an annular turbine rotor was investigated experimentally using a laser Doppler velocimetry (LDV) system. Detailed measurements of the time-averaged and time-resolved distributions of the velocity, flow angle, turbulence intensity, etc., were carried out at a very low Reynolds number condition, Reout=3.5×104. The data obtained were analyzed from the viewpoints of both an absolute (stationary) frame of reference and a relative (rotating) frame of reference. The effect of the turbine nozzle wake and secondary vortices on the flow field inside the rotor passage was clearly captured. It was found that the nozzle wake and secondary vortices are suddenly distorted at the rotor inlet, because of the rotating potential field of the rotor. The nozzle flow (wake and passage vortices) and the rotor flow (boundary layer, wake, tip leakage vortex, and passage vortices) interact intensively inside the rotor passage.

scholarly journals Influence of Axial Clearance on Water-Jet Axial Flow Pump

2021 ◽  
Author(s):  
Chen Li ◽  
Hongming Wang
Keyword(s):  
Flow Field ◽  
Axial Flow ◽  
Pressure Rise ◽  
Leading Edge ◽  
Hydraulic Performance ◽  
Suction Surface ◽  
Surface Separation ◽  
Axial Clearance ◽  
Axial Flow Pump ◽  
Flow Pump

Three dimensional Reynolds averaged N-S equation and S-A turbulent model were adopted to simulate the flow field and hydraulic performance of the waterjet axial flow pump with the different impeller axial clearance. The numerical research results show that with the increase of axial clearance size, total pressure and static pressure rise at first and then decreases, torque and shaft power remain basically unchanged, the efficiency decreases gradually, the suction surface separation zone of stator expanded under the design condition. When the axial clearance is 30mm, the pump hydraulic performance and flow field are the best, and stator load distribution is the most uniform. When the axial clearance is 40–50mm the load of the lower part of stator leading edge is reduced greatly, which is not conducive to maintain static blade strength and maintain the stator rectifying action.

LDV Measurements of Unsteady Midspan Flow in a Turbine Rotor at Low Reynolds Number

2003 ◽  
Author(s):  
Takayuki Matsunuma ◽  
Yasukata Tsutsui
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Reynolds Stress ◽  
Low Reynolds Number ◽  
Axial Flow ◽  
Turbine Rotor ◽  
Mean Flow ◽  
Suction Surface ◽  
Flow Angle ◽  
Low Reynolds

In this study, the unsteady flow field at midspan in an axial-flow turbine rotor at low Reynolds number (Reout,RT = 3.6×104) was investigated experimentally using a laser Doppler velocimetry (LDV) system. The time-averaged and time-dependent distributions of velocity, flow angle, vorticity, turbulence intensity, and Reynolds stress were analyzed in terms of both absolute and relative frames of reference. In the relative frame of reference, the nozzle wake had a slip velocity relative to the mean flow, which caused the wake fluid to migrate across the rotor passage and accumulate on the rotor suction surface. The effect of the nozzle wake on the flow field inside the rotor was determined qualitatively and quantitatively. The flow separation occurred at the rotor suction surface because of the low Reynolds number. The position of the separation onset fluctuated periodically as much as about 10% of the rotor axial-chord by the rotor-stator interaction. The turbulence in the wake region was anisotropy, and it exhibited strong Reynolds stress.

scholarly journals Unsteady Flow Field due to Nozzle Wake Interaction With the Rotor in an Axial Flow Turbine: Part II — Rotor Exit Flow Field

1995 ◽  
Author(s):  
Michael A. Zaccaria ◽  
Budugur Lakshminarayana
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Velocity Component ◽  
Axial Flow ◽  
Turbine Rotor ◽  
Edge Region ◽  
Trailing Edge ◽  
Rotor Wake ◽  
Cross Correlations ◽  
Far Wake

The two-dimensional steady and unsteady flow field at midspan in a turbine rotor has been investigated experimentally using an LDV with an emphasis on the interaction of the nozzle wake with the rotor flow field. The velocity measurements are decomposed into a time-averaged velocity, a periodic velocity component and an unresolved velocity component. The results in the rotor passage were presented in Part I. The flow field downstream of the rotor is presented in this paper. The rotor wake profiles and their decay characteristics were analyzed. Correlations are presented which match the decay of the various wake properties. The rotor wake velocity defect decays rapidly in the trailing edge region, becoming less rapid in the near and far wake regions. The rotor wake semi-wake width increases rapidly in the trailing edge region and then grows more gradually in the near and far wake regions. The decay of the maximum unresolved unsteadiness and maximum unresolved velocity cross correlations are very rapid in the trailing edge region and this trend slows in the far wake region. In the trailing edge region, the maximum periodic velocity correlations are much larger than the maximum unresolved velocity correlations. But the periodic velocity correlations decay much faster than the unresolved velocity correlations. The interaction of the nozzle and rotor wakes are also studied. While the interaction of the nozzle wake with the rotor wake does not influence the decay rate of the various wake properties, it does change the magnitude of the properties. These and other results will be presented in this paper.

Unsteady Numerical Simulation of Shock Systems in Vaneless Counter-Rotating Turbine

2005 ◽  
Author(s):  
Huishe Wang ◽  
Qingjun Zhao ◽  
Xiaolu Zhao ◽  
Jianzhong Xu
Keyword(s):  
Numerical Simulation ◽  
Mach Number ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Nozzle Design ◽  
Suction Surface ◽  
Rotor Wake ◽  
Wake Interaction ◽  
Unsteady Numerical Simulation ◽  
Almost All

A detailed unsteady numerical simulation has been carried out to investigate the shock systems in the high pressure (HP) turbine rotor and unsteady shock-wake interaction between coupled blade rows in a 1+1/2 counter-rotating turbine (VCRT). For the VCRT HP rotor, due to the convergent-divergent nozzle design, along almost all the span, fishtail shock systems appear after the trailing edge, where the pitch averaged relative Mach number is exceeding the value of 1.4 and up to 1.5 approximately (except the both endwalls). A group of pressure waves create from the suction surface after about 60% axial chord in the VCRT HP rotor, and those waves interact with the inner-extending shock (IES). IES first impinges on the next HP rotor suction surface and its echo wave is strong enough and cannot be neglected, then the echo wave interacts with the HP rotor wake. Strongly influenced by the HP rotor wake and LP rotor, the HP rotor outer-extending shock (OES) varies periodically when moving from one LP rotor leading edge to the next. In VCRT, the relative Mach numbers in front of IES and OES are not equal, and in front of IES, the maximum relative Mach number is more than 2.0, but in front of OES, the maximum relative Mach number is less than 1.9. Moreover, behind IES and OES, the flow is supersonic. Though the shocks are intensified in VCRT, the loss resulted in by the shocks is acceptable, and the HP rotor using convergent-divergent nozzle design can obtain major benefits.

Sign in / Sign up

Export Citation Format

Share Document