Rim Seal Ingestion in a Turbine Stage From 360-Degree Time Dependent Numerical Simulations

2012 ◽  
Author(s):  
Cheng-Zhang Wang ◽  
Senthil Prasad Mathiyalagan ◽  
Bruce V. Johnson ◽  
J. Axel Glahn ◽  
David F. Cloud
Keyword(s):  
Numerical Simulations ◽  
Flow Rate ◽  
Pressure Field ◽  
Secondary Flows ◽  
Coolant Flow ◽  
Time Dependent ◽  
Coolant Flow Rate ◽  
Turbine Stage ◽  
Sector Model ◽  
Wall Boundary Layer

Numerical simulations of turbine rim seal experiments are conducted with a time-dependent, 360-degree CFD model of the complete turbine stage with a rim seal and cavity. The turbine stage has 22 vanes and 28 blades and is modeled with a uniform flow upstream of the vane inlet, a pressure condition downstream of the blades and three coolant flow conditions previously employed during experiments at Arizona State University. The simulations show the pressure fields downstream of the vanes and upstream of the blades interacting to form a complex pressure pattern above the rim seal. Circumferential distributions of 15 and 17 sets of ingress and egress velocities flow through the rim seal at the two modest coolant flow rate conditions. These flow distributions rotate at wheel speed and are not associated with the numbers of blades or vanes. The seal velocity distribution for a high coolant flow rate with little or no ingestion into the stator wall boundary layer is associated with the blade pressure field. These pressure field characteristics and the rim seal ingress/egress pattern provide new insight to the physics of rim seal ingestion. Flow patterns within the rim cavity have large cells that rotate in the wheel direction at a slightly slower speed. These secondary flows are similar to structures noted in previous a 360-degree model and large sector models but not obtained in a single blade or vane sector model with periodic boundary condition at sector boundaries. The predictions of pressure profiles, sealing effectiveness and cavity velocity components are compared with experimental data.

Rim Seal Ingestion in a Turbine Stage From 360 Degree Time-Dependent Numerical Simulations

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
Cheng-Zhang Wang ◽  
Senthil Prasad Mathiyalagan ◽  
Bruce V. Johnson ◽  
J. Axel Glahn ◽  
David F. Cloud
Keyword(s):  
Numerical Simulations ◽  
Flow Rate ◽  
Pressure Field ◽  
Secondary Flows ◽  
Coolant Flow ◽  
Time Dependent ◽  
Coolant Flow Rate ◽  
Turbine Stage ◽  
Sector Model ◽  
Wall Boundary Layer

Numerical simulations of turbine rim seal experiments are conducted with a time-dependent, 360 deg computational fluid dynamics (CFD) model of the complete turbine stage with a rim seal and cavity to increase understanding of the rim seal ingestion physics. The turbine stage has 22 vanes and 28 blades and is modeled with a uniform flow upstream of the vane inlet, a pressure condition downstream of the blades, and three coolant flow conditions previously employed during experiments at Arizona State University. The simulations show the pressure fields downstream of the vanes and upstream of the blades interacting to form a complex pressure pattern above the rim seal. Circumferential distributions of 15 to 17 sets of ingress and egress velocities flow through the rim seal at the two modest coolant flow rate conditions. These flow distributions rotate at approximately wheel speed and are not equal to the numbers of blades or vanes. The seal velocity distribution for a high coolant flow rate with little or no ingestion into the stator wall boundary layer is associated with the blade pressure field. These pressure field characteristics and the rim seal ingress/egress pattern provide new insight to the physics of rim seal ingestion. Flow patterns within the rim cavity have large cells that rotate in the wheel direction at a slightly slower speed. These secondary flows are similar to structures noted in previous a 360 deg model and large sector models but not obtained in a single blade or vane sector model with periodic boundary condition at sector boundaries. The predictions of pressure profiles, sealing effectiveness, and cavity velocity components are compared with experimental data.

Numerical Studies on the Effect of Tip Clearance and Tip Cooling Flow on Endwall Losses of an Unshrouded Axial Turbine Rotor

2013 ◽  
Author(s):  
K. Asgar Ali ◽  
Quamber H. Nagpurwala ◽  
Abdul Nassar ◽  
S. V. Ramanamurthy
Keyword(s):  
Flow Rate ◽  
Layer Growth ◽  
Coolant Flow ◽  
Tip Clearance ◽  
Coolant Flow Rate ◽  
Total Efficiency ◽  
Turbine Stage ◽  
Suction Surface ◽  
Axial Turbine ◽  
Ejection Rate

This paper deals with the numerical investigations on a low pressure axial turbine stage to assess the effect of variation in rotor tip clearance and tip coolant ejection rate on the end wall losses. The rotor, along with the NGV, was modeled to represent the entire turbine stage. The CFX TASCflow software was used to perform steady state analysis for different rotor tip clearances and different tip coolant ejection rates. The locations of the cooling slots were identified on the blade tip and the coolant ejection rate was specified at these areas. The simulations were carried out with tip clearances of 0%, 1% and 2% of blade height and ejection flow rates of 0.5%, 0.75% and 1% of main turbine flow rate. It is shown that the size and strength of the leakage vortex is directly related to the tip clearance. The reduction in efficiency is not in linearity with the tip clearance owing to the effect of boundary layer growth on the end walls. Introduction of the tip coolant flow shows increased total–total efficiency compared to that of the uncooled tip. This is attributed to a reduction in the strength of the leakage vortex due to reduced cross-flow over the tip clearance from pressure surface to suction surface. At a coolant flow rate of 0.75% of the main flow rate, there is significant increase in efficiency of about 0.5%. Optimum tip clearance and coolant flow rate are obtained based on the results of the present analysis.

Effects of Endwall Film Coolant Flow Rate on Secondary Flows and Coolant Mixing in a First Stage Nozzle Guide Vane

2021 ◽  
Author(s):  
Mahmood Alqefl ◽  
Kedar Nawathe ◽  
Pingting Chen ◽  
Rui Zhu ◽  
Yong Kim ◽  
...  
Keyword(s):  
Flow Rate ◽  
Guide Vane ◽  
Secondary Flows ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

Heat Transfer for the Blade of a Cooled Stage and One-Half High-Pressure Turbine—Part II: Independent Influences of Vane Trailing Edge and Purge Cooling

2011 ◽  
Vol 134 (3) ◽  
Author(s):  
R. M. Mathison ◽  
C. W. Haldeman ◽  
M. G. Dunn
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Flow Rate ◽  
Pressure Field ◽  
Its Region ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
High Pressure Turbine ◽  
Suction Surface ◽  
Trailing Edge

The independent influences of vane trailing edge and purge cooling are studied in detail for a one-and-one-half stage transonic high-pressure turbine operating at design-corrected conditions. This paper builds on the conclusions of Part I, which investigated the combined influence of all cooling circuits. Heat-flux measurements for the airfoil, platform, tip, and root of the turbine blade, as well as the shroud and the vane side of the purge cavity, are used to track the influence of cooling flow. By independently varying the coolant flow rate through the vane trailing edge or purge circuit, the region of influence of each circuit can be isolated. Vane trailing edge cooling is found to create the largest reductions in blade heat transfer. However, much of the coolant accumulates on the blade suction surface and little influence is observed for the pressure surface. In contrast, the purge cooling is able to cause small reductions in heat transfer on both the suction and pressure surfaces of the airfoil. Its region of influence is limited to near the hub, but given that the purge coolant mass flow rate is 1/8 that of the vane trailing edge, it is impressive that any impact is observed at all. The cooling contributions of these two circuits account for nearly all of the cooling reductions observed for all three circuits in Part I, indicating that the vane inner cooling circuit that feeds most of the vane film-cooling holes has little impact on the downstream blade heat transfer. Time-accurate pressure measurements provide further insight into the complex interactions in the purge region that govern purge coolant injection. While the pressures supplying the purge coolant and the overall coolant flow rate remain fairly constant, the interactions of the vane pressure field and the rotor pressure field create moving regions of high pressure and low pressure at the exit of the cavity. This results in pulsing regions of injection and ingestion.

Heat Transfer for the Blade of a Cooled Stage and One-Half High-Pressure Turbine: Part II—Independent Influences of Vane Trailing Edge and Purge Cooling

2010 ◽  
Author(s):  
R. M. Mathison ◽  
C. W. Haldeman ◽  
M. G. Dunn
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Flow Rate ◽  
Pressure Field ◽  
Its Region ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
High Pressure Turbine ◽  
Suction Surface ◽  
Trailing Edge

The independent influences of vane trailing edge and purge cooling are studied in detail for a one-and-one-half stage transonic high-pressure turbine operating at design corrected conditions. This paper builds on the conclusions of Part I, which investigated the combined influence of all cooling circuits. Heat-flux measurements for the airfoil, platform, tip, and root of the turbine blade as well as the shroud and the vane side of the purge cavity are used to track the influence of cooling flow. By independently varying the coolant flow rate through the vane trailing edge or purge circuit, the region of influence of each circuit can be isolated. Vane trailing edge cooling is found to create the largest reductions in blade heat transfer. However, much of the coolant accumulates on the blade suction surface and little influence is observed for the pressure surface. In contrast, the purge cooling is able to cause small reductions in heat transfer on both the suction and pressure surfaces of the airfoil. Its region of influence is limited to near the hub, but given that the purge coolant mass flow rate is 1/8th that of the vane trailing edge, it is impressive that any impact is observed at all. The cooling contributions of these two circuits account for nearly all of the cooling reductions observed for all three circuits in Part I, indicating that the vane inner cooling circuit that feeds most of the vane film-cooling holes has little impact on the downstream blade heat transfer. Time-accurate pressure measurements provide further insight into the complex interactions in the purge region that govern purge coolant injection. While the pressures supplying the purge coolant and the overall coolant flow rate remain fairly constant, the interactions of the vane pressure field and the rotor pressure field create moving regions of high pressure and low pressure at the exit of the cavity. This results in pulsing regions of injection and ingestion.

Effect of Outer Fin Axial Gap on the Sealing Effectiveness and Fluid Dynamics of Radial Rim Seal

2017 ◽  
Author(s):  
Zhigang Li ◽  
Jun Li ◽  
Liming Song ◽  
Qing Gao ◽  
Xin Yan ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Flow Rate ◽  
Gas Turbines ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Navier Stokes ◽  
Hot Gas

The modern gas turbine is widely applied in the aviation propulsion and power generation. The rim seal is usually designed at the periphery of the wheel-space and prevented the hot gas ingestion in modern gas turbines. The high sealing effectiveness of rim seal can improve the aerodynamic performance of gas turbines and avoid of the disc overheating. Effect of outer fin axial gap of radial rim seal on the sealing effectiveness and fluid dynamics was numerically investigated in this work. The sealing effectiveness and fluid dynamics of radial rim seal with three different outer fin axial gaps was conducted at different coolant flow rates using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) and SST turbulent model solutions. The accuracy of the presented numerical approach for the prediction of the sealing performance of the turbine rim seal was demonstrated. The obtained results show that the sealing effectiveness of radial rim seal increases with increase of coolant flow rate at the fixed axial outer fin gap. The sealing effectiveness increases with decrease of the axial outer fin gap at the fixed coolant flow rate. Furthermore, at the fixed coolant flow rate, the hot gas ingestion increases with the increase of the axial outer fin gap. This flow behavior intensifies the interaction between the hot gas and coolant flow at the clearance of radial rim seal. The preswirl coefficient in the wheel-space cavity is also illustrated to analyze the flow dynamics of radial rim seal at different axial outer fin gaps.

Simulation on the Temperature Field of Milling Roller Using Fluent Software

2015 ◽  
Vol 1095 ◽  
pp. 846-850
Author(s):  
Min Wang ◽  
Ke Ping Zhang ◽  
Feng Wei Zhang
Keyword(s):  
Temperature Field ◽  
Flow Rate ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Roller Surface ◽  
Fluent Software ◽  
The Law

In order to study the law between the internal coolant flow rate and the temperature of milling roller, the temperature field of water-cooled roller was simulated with Fluent software. The results showed that with the increase of the coolant flow rate, the temperature on roller surface decreased, but after the flow rate of coolant increased to 3.5 kg/s, the temperature of roller maintained invariant almost, so 3.5 kg/s was the best flow rate.

Analytical Model Quantifying the Net Coolant Flow Rate to a Microstructured Copper Surface validated with Two-Phase PIV Measurements

2021 ◽  
Author(s):  
Matt Harrison ◽  
Joshua Gess
Keyword(s):  
Heat Transfer ◽  
Analytical Model ◽  
Flow Rate ◽  
Circular Disk ◽  
Nucleate Boiling ◽  
High Heat ◽  
Heat Fluxes ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Two Phase

Abstract Using Particle Image Velocimetry (PIV), the amount of fluid required to sustain nucleate boiling was quantified to a microstructured copper circular disk. Having prepared the disk with preferential nucleation sites, an analytical model of the net coolant flow rate requirements to a single site has been produced and validated against experimental data. The model assumes that there are three primary phenomena contributing to the coolant flow rate requirements at the boiling surface; radial growth of vapor throughout incipience to departure, bubble rise, and natural convection around the periphery. The total mass flowrate is the sum of these contributing portions. The model accurately predicts the quenching fluid flow rate at low and high heat fluxes with 4% and 30% error of the measured value respectively. For the microstructured surface examined in this study, coolant flow rate requirements ranged from 0.1 to 0.16 kg/sec for a range of heat fluxes from 5.5 to 11.0 W/cm2. Under subcooled conditions, the coolant flow rate requirements plummeted to a nearly negligible value due to domination of transient conduction as the primary heat transfer mechanism at the liquid/vapor/surface interface. PIV and the validated analytical model could be used as a test standard where the amount of coolant the surface needs in relation to its heat transfer coefficient or thermal resistance is a benchmark for the efficacy of a standard surface or boiling enhancement coating/surface structure.

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