Fine Particulate Deposition in an Effusion Plate Geometry

2019 ◽  
Author(s):  
B. Varney ◽  
B. Barker ◽  
J. P. Bons ◽  
T. Wolff ◽  
P. Gnanaselvam
Keyword(s):  
Constant Pressure ◽  
Pressure Ratio ◽  
Diameter Ratio ◽  
Hole Diameter ◽  
Gas Turbine Combustor ◽  
Plate Temperature ◽  
Test Fixture ◽  
Fine Particulate ◽  
Inclination Angles ◽  
Compound Angle

Abstract Fine particulate deposition testing was conducted with an effusion plate film cooling geometry representative of a gas turbine combustor liner. Preheated coolant air with airborne particulate (0–10 μm Arizona Road Dust) was fed into an effusion plate test fixture with the flow parallel to the target plate. The test fixture was located in an electric kiln that establishes the elevated plate temperature, similar to a gas turbine combustor. Experiments were conducted at constant pressure ratio (1.03) across the effusion plate which consists of an array of approximately 100 effusion holes. Test variables include hole diameter, length/diameter ratio, inclination angle and compound angle. In addition, coolant temperature and plate temperature were varied independently to determine their influence on in-hole deposition. All tests were continued until the effusion holes had blocked to produce a 25% reduction in mass flow rate while maintaining constant pressure ratio. The blockage was found to be more sensitive to flow temperature than to plate temperature over the range studied. Blockage was insensitive to effusion hole diameter from 0.5 to 0.75 mm, but increased dramatically for hole diameter below 0.5mm. Blockage shows a moderate increase with hole length/diameter ratio. The strongest dependency was found with the inclination angle; roughly an order of magnitude increase in deposition rate was documented when increasing from a 30° to 150°. A compound angle of 45° caused a negligible change in blockage, while a compound angle of 90° increased blockage for low inclination angles while decreasing it for high inclination angles. For the flow angle dependency, interpretation is provided by means of CFD simulations of the particulate delivery and initial deposition location prediction using the OSU Deposition Model.

Fine Particulate Deposition in an Effusion Plate Geometry

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Bruce Varney ◽  
Brett Barker ◽  
Jeffrey Bons ◽  
Pritheesh Gnanaselvam ◽  
Trent Wolff
Keyword(s):  
Gas Turbine ◽  
Diameter Ratio ◽  
Hole Diameter ◽  
Gas Turbine Combustor ◽  
Plate Temperature ◽  
Test Fixture ◽  
Fine Particulate ◽  
Inclination Angles ◽  
Compound Angle ◽  
Plate Geometry

Abstract Fine particulate deposition testing was conducted with an effusion plate geometry representative of a gas turbine combustor liner. Preheated coolant air with airborne particulate was fed into an effusion plate test fixture with the flow parallel to the target plate. The test fixture was in an electric kiln that establishes elevated plate temperature, similar to a gas turbine combustor. Test variables include hole diameter, length/diameter ratio, inclination angle, and compound angle. In addition, coolant and plate temperature were varied independently to determine their influence. All tests were continued until the effusion holes had blocked to produce a 25% reduction in mass flowrate while maintaining constant pressure ratio. The blockage rate was found to be more sensitive to flow temperature than to plate temperature over the range studied. Blockage rate was insensitive to effusion hole diameter from 0.5 to 0.75 mm but increased dramatically for hole diameter below 0.5 mm. Blockage shows a moderate increase with hole length/diameter ratio. The strongest dependency was found with the inclination angle; roughly an order of magnitude increase in blockage rate was documented when increasing from a 30 deg to 150 deg. A compound angle of 45 deg caused a negligible change in blockage rate, while a compound angle of 90 deg increased blockage rate for low inclination angles while decreasing it for high inclination angles. For the flow angle dependency, interpretation is provided by means of computational fluid dynamics (CFD) simulations of the particulate delivery and initial deposition location prediction using the Ohio State University (OSU) deposition model.

Effects of Hole Pitch to Diameter Ratio P/D of Impingement and Film Hole on Laminated Cooling Effectiveness

2017 ◽  
Author(s):  
Weilun Zhou ◽  
Qinghua Deng ◽  
Wei He ◽  
Zhenping Feng
Keyword(s):  
Mass Flux ◽  
Pressure Loss ◽  
Pressure Ratio ◽  
Diameter Ratio ◽  
Hole Diameter ◽  
Heat Transfer Analysis ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
System Pressure ◽  
The Difference

The laminated cooling, also known as impingement-effusion cooling, is believed to be a promising gas turbine blade cooling technique. In this paper, conjugate heat transfer analysis was employed to investigate the overall cooling effectiveness and total pressure loss of the laminated cooling configuration. The pitch to film hole diameter ratio P/Df of 3, 4, 5, 6, combined with pitch to impingement hole diameter ratio P/Di of 4, 6, 8, 10, are studied at the coolant mass flux G of 0.5, 1.0, 1.5, 2.0 kg/(sm2bar) respectively. The results show that overall cooling effectiveness of laminated cooling configuration increases with the decreasing of P/Df and the increasing of the coolant mass flux in general. However P/Df smaller than 3 may leads to a serious blocking in first few film holes at low coolant mass flux. The large P/Di that makes the Mach number of impingement flow greater than 0.16 may cause unacceptable pressure loss. The increment of overall cooling effectiveness depends on the difference between the deterioration of external cooling and the enhancement of internal cooling. Pressure loss increases exponentially with P/Di and G, and it increases more slowly with P/Df that compared to P/Di and G. The mixing loss takes up the most pressure loss at low coolant mass flux. With the increasing of the whole pressure loss, the proportion of throttling loss and laminated loss becomes larger and finally takes up the most of the whole pressure loss. When the sum of throttling loss and laminated loss is greater than mixing loss, the increment of system pressure ratio is unreasonable that compared to the increment of overall cooling effectiveness.

scholarly journals A new method for calculating the sonic conductance of airflow through a short-tube orifice

2017 ◽  
Vol 9 (2) ◽  
pp. 168781401668726 ◽  
Author(s):  
Fan Yang ◽  
Gangyan Li ◽  
Dawei Hu ◽  
Toshiharu Kagawa
Keyword(s):  
Flow Rate ◽  
Critical Pressure ◽  
Pressure Ratio ◽  
Momentum Equation ◽  
Diameter Ratio ◽  
Test Method ◽  
Theoretical Formula ◽  
Engineering Applications ◽  
Short Tube ◽  
Length To Diameter Ratio

In this study, we proposed a method for calculating the sonic conductance of a short-tube orifice. First, we derived a formula for calculating the sonic conductance based on a continuity equation, a momentum equation and the definition of flow-rate characteristics. The flow-rate characteristics of different orifices were then measured using the upstream constant-pressure test method in ISO 6358. Based on these test data, the theoretical formula was simplified using the least squares fitting method, the accuracy of which was verified experimentally. Finally, the effects of the diameter ratio, the length-to-diameter ratio and the critical pressure ratio were analysed with reference to engineering applications, and a simplified formula was derived. We conclude that the influence of the diameter ratio is greater than that of the length-to-diameter ratio. When the length-to-diameter ratio is <5, its effect can be neglected. The critical pressure ratio has little effect on the sonic conductance of a short-tube orifice, and it can be set to 0.5 when calculating the sonic conductance in engineering applications. The formula proposed in this study is highly accurate with a mean error of <3%.

Modeling of a Steam Turbine Including Partial Arc Admission for Use in a Process Simulation Software Environment

2011 ◽  
Author(s):  
Eric Liese
Keyword(s):  
Steam Turbine ◽  
Process Simulation ◽  
Process Model ◽  
Constant Pressure ◽  
Pressure Ratio ◽  
Simulation Software ◽  
State Variables ◽  
Steam Turbines ◽  
Software Environment ◽  
Last Stage

A dynamic process model of a steam turbine, including partial arc admission operation, is presented. Models were made for the first stage and last stage, with the middle stages presently assumed to have a constant pressure ratio and efficiency. A condenser model is also presented. The paper discusses the function and importance of the steam turbines entrance design and the first stage. The results for steam turbines with a partial arc entrance are shown, and compare well with experimental data available in the literature, in particular, the “valve loop” behavior as the steam flow rate is reduced. This is important to model correctly since it significantly influences the downstream state variables of the steam, and thus the characteristic of the entire steam turbine, e.g., state conditions at extractions, overall turbine flow, and condenser behavior. The importance of the last stage (the stage just upstream of the condenser) in determining the overall flowrate and exhaust conditions to the condenser is described and shown via results.

Super-Fine Structure in the Critical Flow-Rate of Critical Flow Venturi Nozzles

2002 ◽  
Author(s):  
Masahiro Ishibashi
Keyword(s):  
Fine Structure ◽  
Steady State ◽  
Discharge Coefficient ◽  
Constant Pressure ◽  
Pressure Ratio ◽  
Critical Flow ◽  
Time Intervals ◽  
Critical Flow Rate ◽  
A Value ◽  
Long Time

It is shown that critical flow Venturi nozzles need time intervals, i.e., more than five hours, to achieve steady state conditions. During these intervals, the discharge coefficient varies gradually to reach a value inherent to the pressure ratio applied. When a nozzle is suddenly put in the critical condition, its discharge coefficient is trapped at a certain value then afterwards approaches gradually to the inherent value. Primary calibrations are considered to have measured the trapped discharge coefficient, whereas nozzles in applications, where a constant pressure ratio is applied for a long time, have a discharge coefficient inherent to the pressure ratio; inherent and trapped coefficients can differ by 0.03–0.04%.

Film Cooling Mechanism of Combined Hole and Saw-tooth Slot

2019 ◽  
Vol 36 (4) ◽  
pp. 425-433
Author(s):  
Wei Zhang ◽  
Shuai Zhou ◽  
Zhuang Wu ◽  
Guangchao Li ◽  
Zhihai Kou
Keyword(s):  
Film Cooling ◽  
Numerical Data ◽  
Diameter Ratio ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Inclination Angles ◽  
Cylindrical Holes ◽  
Cooling Mechanism ◽  
Experimental Values

Abstract Film cooling performance of one row of cylindrical holes integrated with saw-tooth slots was numerically studied at blowing ratios of 0.5, 1.0 1.5 and 2.0 respectively. The saw-tooth slot concept combines the advantages both of easy machining for the slot and of the high film cooling effectiveness caused by the anti-vortex induced by the shaped hole. The film holes have an inclination angles of 30°, length to diameter ratio of 4 and pitch to diameter ratio of 3. The corner angles of the saw-tooth are 60°, 90°, 120°, 150° and 180° respectively. The 180° corner angle corresponds to a standard transverse slot. The emphasis of this other is on the influence of the corner angles of the saw-tooth on film cooling effectiveness. The flow field and thermal field were obtained to explain the mechanism of film cooling performance improvement by the saw-tooth slot. The results show that the numerical data agrees with the experimental values for the cylindrical holes. Relatively small corner angles generate uniform local film cooling effectiveness and high spanwise averaged film cooling effectiveness due to the coolant ejected from the hole smoothly flowing into the slot. The effect of corner angles strongly depends on blowing ratios. The increase of x/D decreases the differences of film cooling effectiveness between various corner angles. At low blowing ratios, an anti-vortex can be found with the spanwise angle of 60° and 120°. At high blowing ratios, an anti-vortex can be found with the spanwise angle of 60°.

scholarly journals Numerical investigation about backflow of film cooling in static turbine blade leading edge

2019 ◽  
Vol 11 (11) ◽  
pp. 168781401988581
Author(s):  
Chao Gao ◽  
Haiwang Li ◽  
Huimin Zhou ◽  
Yiwen Ma ◽  
Ruquan You
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Hole Diameter ◽  
Computational Method ◽  
Coverage Area ◽  
Slowing Down ◽  
Film Cooling Holes ◽  
Blade Leading Edge

In this article, film cooling characteristics, especially the phenomenon of backflow for the straight turbine blade leading edge, are investigated. Shear stress transport k-ω turbulence model and structured grids are employed to assure the accuracy of the simulation, and the computational method is verified by the available experimental data. The influences of blow ratio, hole diameter, and the spacing between holes in each row are analyzed. The formation mechanism of backflow is discussed to prevent it from happening or relieve the degree of backflow, thereby to improve the cooling efficiency. The results showed that backflow can be avoided by adjusting the structure and the layout of film cooling holes. With increase in blow ratio, the cooling film becomes more obvious at first and then fades gradually for departing from the blade surface. The jet flow is influenced by the total pressure ratio between coolant cavity and surface of blade leading edge. Smaller film hole diameter and larger hole spacing makes it easier to eject coolant and form continuous film by slowing down the pressure in the cavity. Increasing ratio of hole spacing to hole diameter ( p/ d) can effectively prevent backflow, whereas larger p/ d also makes the film coverage area smaller.

The Effects of Seawater Immersion on the Bearing Strength of Woven-Glass–Epoxy Prepreg Pin-Loaded Joints

2011 ◽  
Vol 21 (2) ◽  
pp. 153-170 ◽  
Author(s):  
AyŞe Öndürücü
Keyword(s):  
Failure Modes ◽  
Failure Load ◽  
Diameter Ratio ◽  
Hole Diameter ◽  
Natural Seawater ◽  
Bearing Strength ◽  
Specimen Width ◽  
Bearing Load ◽  
Mechanically Fastened ◽  
Ultimate Failure

This study considers the bearing strengths and failure modes of woven-glass–epoxy prepreg composite mechanically fastened joints. For the study, the specimens were immersed in natural seawater in the laboratory for over 1 year. The edge distance-to-hole diameter ( E/ D) ratio and the specimen width-to-hole-diameter ratio ( W/ D) were systematically altered during experiments. Failure modes were determined by observing the failure regions on the specimens. Damage progression in pin-loaded specimens prepared from woven-glass–epoxy prepreg was also examined using a scanning electron microscopy for three different percentages of ultimate failure load. According to the experimental investigation results, it was observed that the bearing load values obtained from the specimens immersed in seawater decreased considerably in comparison to unimmersed specimens.

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