Measurement and Visualization of Leakage Effects of Rounded Teeth Tips and Rub-Grooves on Stepped Labyrinths

2000 ◽  
Vol 123 (3) ◽  
pp. 604-611 ◽  
Author(s):  
D. L. Rhode ◽  
B. F. Allen
Keyword(s):  
Flow Visualization ◽  
Large Scale ◽  
Recirculation Zone ◽  
Step Height ◽  
Test Facility ◽  
Leakage Resistance ◽  
Large Step ◽  
Fluorescein Dye ◽  
Resistance Decrease ◽  
Flow Tracer

The effect of rounded labyrinth teeth tips and worn abradable lands has been found to give substantially increased leakage, which is well known to give reduced machine efficiency. Very little information concerning this exists, and some of the first measurements and visualization movies for stepped labyrinths are provided here to give an enhanced understanding of this phenomenon. A unique, very large-scale seal test facility was used. Glitter, and alternatively fluorescein dye, was employed as the flow tracer material. The flow visualization movies were digitally stored on the hard drive of a computer. Large decreases of leakage resistance due to the presence of worn teeth as well as rub-grooves were found. For the cases considered, the leakage resistance decrease for the large step height configurations were 85 percent, 55 percent, and 70 percent for the small, medium, and large pre-rub clearances, respectively. It was also found that the resistance varied with wear geometry, in order from highest to lowest resistance, as (a) ungrooved-unrounded-teeth, (b) ungrooved-rounded-teeth, (c) grooved-unrounded-teeth and (d) grooved-rounded-teeth. Further, a substantial tooth tip recirculation zone was visually observed only for the grooved-unrounded-teeth cases, and it was shown to be the mechanism by which the unrounded teeth give this configuration a higher resistance than do the rounded teeth.

Measurement and Visualization of Leakage Effects of Rounded Teeth Tips and Rub-Grooves on Stepped Labyrinths

1999 ◽  
Author(s):  
David L. Rhode ◽  
Brian F. Allen
Keyword(s):  
Flow Visualization ◽  
Large Scale ◽  
Recirculation Zone ◽  
Step Height ◽  
Test Facility ◽  
Leakage Resistance ◽  
Large Step ◽  
Fluorescein Dye ◽  
Resistance Decrease ◽  
Flow Tracer

The effect of rounded labyrinth teeth tips and worn abradable lands has been found to give substantially increased leakage, which is well known to give reduced machine efficiency. Very little information concerning this exists, and some of the first measurements and visualization movies for stepped labyrinths are provided here to give an enhanced understanding of this phenomenon. A unique, very large-scale seal test facility was used. Glitter, and alternatively fluorescein dye, was employed as the flow tracer material. The flow visualization movies were digitally stored on the hard drive of a computer. Large decreases of leakage resistance due to the presence of worn teeth as well as rub-grooves were found. For the cases considered, the leakage resistance decrease for the large step height configurations were 85 percent, 55 percent and 70 percent for the small, medium and large pre-rub clearances, respectively. It was also found that the resistance varied with wear geometry, in order from highest to lowest resistance, as: (a) ungrooved-unrounded-teeth, (b) ungrooved-rounded-teeth, (c) grooved-unrounded-teeth and (d) grooved-rounded-teeth. Further, a substantial tooth tip recirculation zone was visually observed only for the grooved-unrounded-teeth cases, and it was shown to be the mechanism by which the unrounded teeth give this configuration a higher resistance than do the rounded teeth.

Flow Visualization and Leakage Measurements of Stepped Labyrinth Seals: Part 1—Annular Groove

1997 ◽  
Vol 119 (4) ◽  
pp. 839-843 ◽  
Author(s):  
D. L. Rhode ◽  
J. W. Johnson ◽  
D. H. Broussard
Keyword(s):  
Flow Visualization ◽  
Large Scale ◽  
Digital Images ◽  
Test Facility ◽  
Labyrinth Seals ◽  
Water Leakage ◽  
Tracer Particles ◽  
Leakage Resistance ◽  
Visualization Experiments ◽  
Resistance Improvement

An improved understanding of a new category of stepped labyrinth seals, which feature a new “annular groove,” was obtained. A water leakage and flow visualization test facility of very large scale (relative to a typical seal) was utilized. Flow visualization experiments using a new method and digital facilities for capturing and editing digital images from an 8 mm video were conducted. The presence of an annular groove machined into the stator land increases the leakage resistance by up to 26 percent for the cases considered here. Tracer particles show the degree of throughflow path penetration into the annular groove (i.e., serpentining), which gives the largest and the smallest leakage resistance improvement over that of the corresponding conventional stepped seal.

Flow Visualization and Leakage Measurements of Stepped Labyrinth Seals: Part 1 — Annular Groove

1996 ◽  
Author(s):  
David L. Rhode ◽  
James W. Johnson ◽  
Daniel H. Broussard
Keyword(s):  
Flow Visualization ◽  
Large Scale ◽  
Digital Images ◽  
Test Facility ◽  
Labyrinth Seals ◽  
Water Leakage ◽  
Tracer Particles ◽  
Leakage Resistance ◽  
Visualization Experiments ◽  
Resistance Improvement

An improved understanding of a new category of stepped labyrinth seals, which feature a new “annular groove”, was obtained. A water leakage and flow visualization test facility of very large scale (relative to a typical seal) was utilized. Flow visualization experiments using a new method and digital facilities for capturing and editing digital images from an 8 mm video were conducted. The presence of an annular groove machined into the stator land increases the leakage resistance by up to 26 percent for the cases considered here. Tracer particles show the degree of throughflow path penetration into the annular groove (i.e. serpentining), which gives the largest and the smallest leakage resistance improvement over that of the corresponding conventional stepped seal.

Flow Visualization and Leakage Measurements of Stepped Labyrinth Seals: Part 2—Sloping Surfaces

1997 ◽  
Vol 119 (4) ◽  
pp. 844-848 ◽  
Author(s):  
D. L. Rhode ◽  
J. S. Younger ◽  
M. D. Wernig
Keyword(s):  
Flow Visualization ◽  
Leading Edge ◽  
Test Facility ◽  
Variable Geometry ◽  
Two Dimensional ◽  
Labyrinth Seals ◽  
Leakage Resistance ◽  
Water Test ◽  
Sloping Surface ◽  
Visualization Techniques

An experimental investigation was conducted to determine the geometry–leakage relationship for advanced, stepped labyrinth seals. A unique, variable-geometry water test facility was constructed and used to acquire leakage resistance measurements for two-dimensional, planar models. Flow visualization techniques were also used to assist in identifying and understanding the turbulence generating flow patterns. It was found that contoured surfaces and restrictor tooth leading-edge shapes of proper dimensions can be incorporated into the cavity geometry to reduce seal leakage. Specifically, the combination of a sloping surface and a curved surface on the rotor within the labyrinth cavity gave significant improvement.

scholarly journals Flow Visualization and Leakage Measurements of Stepped Labyrinth Seals: Part 2 — Sloping Surfaces

1996 ◽  
Author(s):  
David L. Rhode ◽  
James S. Younger ◽  
Marcus D. Wernig
Keyword(s):  
Flow Visualization ◽  
Leading Edge ◽  
Test Facility ◽  
Variable Geometry ◽  
Two Dimensional ◽  
Labyrinth Seals ◽  
Leakage Resistance ◽  
Water Test ◽  
Sloping Surface ◽  
Visualization Techniques

An experimental investigation was conducted to determine the geometry-leakage relationship for advanced, stepped labyrinth seals. A unique, variable-geometry water test facility was constructed and used to acquire leakage resistance measurements for two-dimensional, planar models. Flow visualization techniques were also used to assist in identifying and understanding the turbulence generating flow patterns. It was found that contoured surfaces and restrictor tooth leading-edge shapes of proper dimensions can be incorporated into the cavity geometry to reduce seal leakage. Specifically, the combination of a sloping surface and a curved surface on the rotor within the labyrinth cavity gave significant improvement.

scholarly journals Experimental Study on Backflow Patterns Induced by a Bilateral Groin Pair with Different Spacing

2021 ◽  
Vol 11 (4) ◽  
pp. 1486
Author(s):  
Cuiping Kuang ◽  
Yuhua Zheng ◽  
Jie Gu ◽  
Qingping Zou ◽  
Xuejian Han
Keyword(s):  
Cross Sections ◽  
Large Scale ◽  
Recirculation Zone ◽  
Flow Direction ◽  
Wake Flow ◽  
Zone Length ◽  
Array Configuration ◽  
Contraction Ratio ◽  
River Training ◽  
Spanwise Velocity

Groins are one of the popular manmade structures to modify the hydraulic flow and sediment response in river training. The spacing between groins is a critical consideration to balance the channel-depth and the cost of construction, which is generally determined by the backflow formed downstream from groins. A series of experiments were conducted using Particle Image Velocimetry (PIV) to observe the influence of groin spacing on the backflow pattern of two bilateral groins. The spacing between groins has significant effect on the behavior of the large-scale recirculation cell behind groins. The magnitude of the wake flow induced by a groin was similar to that induced by another groin on the other side, but the flow direction is opposite. The spanwise velocity near the groin tip dictates the recirculation zone width behind the groins due to the strong links between the spanwise velocity and the contraction ratio of channel cross-sections between groins. Based on previous studies and present experimental results, quantitative empirical relationships are proposed to calculate the recirculation zone length behind groins alternately placed at different spacing along riverbanks. This study provides better understanding and a robust formula to assess the backflow extent of alternate groins and identify the optimum groins array configuration.

Performance of Core Exit Thermocouple for PWR Accident Management Action in Vessel Top Break LOCA Simulation Experiment at OECD/NEA ROSA Project

2008 ◽  
Author(s):  
Mitsuhiro Suzuki ◽  
Takeshi Takeda ◽  
Hideo Nakamura
Keyword(s):  
Time Delay ◽  
Large Scale ◽  
Simulation Experiment ◽  
Three Dimensional ◽  
Test Facility ◽  
Large Temperature ◽  
Energy Agency ◽  
Pressurized Water ◽  
The Core ◽  
Accident Management

Presented are experiment results of the Large Scale Test Facility (LSTF) conducted at the Japan Atomic Energy Agency (JAEA) with a focus on core exit thermocouple (CET) performance to detect core overheat during a vessel top break loss-of-coolant accident (LOCA) simulation experiment. The CET temperatures are used to start accident management (AM) action to quickly depressurize steam generator (SG) secondary sides in case of core temperature excursion. Test 6-1 is the first test of the OECD/NEA ROSA Project started in 2005, simulating withdraw of a control rod drive mechanism penetration nozzle at the vessel top head. The break size is equivalent to 1.9% cold leg break. The AM action was initiated when CET temperature rose up to 623K. There was no reflux water fallback onto the CETs during the core heat-up period. The core overheat, however, was detected with a time delay of about 230s. In addition, a large temperature discrepancy was observed between the CETs and the hottest core region. This paper clarifies the reasons of time delay and temperature discrepancy between the CETs and heated core during boil-off including three-dimensional steam flows in the core and core exit. The paper discusses applicability of the LSTF CET performance to pressurized water reactor (PWR) conditions and a possibility of alternative indicators for earlier AM action than in Test 6-1 is studied by using symptom-based plant parameters such as a reactor vessel water level detection.

scholarly journals Simple tunable dual-wavelength fiber laser and multiple self-mixing interferometry to large step height measurement

2016 ◽  
Vol 24 (19) ◽  
pp. 21880 ◽  
Author(s):  
Lianlian Dong ◽  
Fang Xie ◽  
Sen Ma ◽  
Yunzhi Wang ◽  
Liang Chen
Keyword(s):  
Fiber Laser ◽  
Dual Wavelength ◽  
Step Height ◽  
Height Measurement ◽  
Large Step

scholarly journals Investigation of unsteady combustion of methane-air flame in a model combustion chamber with swirling flow

2021 ◽  
Vol 2119 (1) ◽  
pp. 012015
Author(s):  
A S Lobasov
Keyword(s):  
Combustion Chamber ◽  
Large Scale ◽  
Recirculation Zone ◽  
Swirling Flow ◽  
Heating Temperature ◽  
Combustion Products ◽  
Flow Dynamics ◽  
Unsteady Combustion ◽  
Stereoscopic Piv ◽  
Large Scale Vortex

Abstract The present paper reports on the investigation of unsteady combustion of a methane-air mixture, including combustion at increased pressure in the combustion chamber and increased temperature of mixture heating for a model gas-turbine swirl burner based on a design by Turbomeca. To measure the velocity and OH fluorescence fields in the flows a combination of stereoscopic PIV and acetone PLIF systems is used. In all cases, the flow dynamics is associated with the movement of large-scale vortex structures in the inner and outer mixing layers and the flow structure corresponds to a swirling jet with a central recirculation zone containing combustion products. An increase in the heating temperature of the mixture and pressure in the combustion chamber leads to a periodic partial separation of the flame from the model swirl nozzle. However, the flow of fuel through the central channel will stabilize the flame.

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