Recombination and Condensation Processes in High Area Ratio Nozzles

ARS Journal ◽  
1962 ◽  
Vol 32 (5) ◽  
pp. 672-680 ◽  
Author(s):  
WALTER T. OLSON
Keyword(s):  
Area Ratio ◽  
High Area

The Effect of Area Ratio Change via Increased Hole Length for Shaped Film Cooling Holes With Constant Expansion Angles

2017 ◽  
Author(s):  
Shane Haydt ◽  
Stephen Lynch ◽  
Scott Lewis
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Area Ratio ◽  
Lateral Expansion ◽  
Blowing Ratio ◽  
High Area ◽  
Expansion Angle ◽  
Ratio Change ◽  
Adiabatic Effectiveness ◽  
Film Cooling Holes

Shaped film cooling holes are used as a cooling technology in gas turbines to reduce metal temperatures and improve durability, and they generally consist of a small metering section connected to a diffuser that expands in one or more directions. The area ratio of these holes is defined as the area at the exit of the diffuser, divided by the area at the metering section. A larger area ratio increases the diffusion of the coolant momentum, leading to lower average momentum of the coolant jet at the exit of the hole and generally better cooling performance. Cooling holes with larger area ratios are also more tolerant of high blowing ratio conditions, and the increased coolant diffusion typically better prevents jet liftoff from occurring. Higher area ratios have traditionally been accomplished by increasing the expansion angle of the diffuser while keeping the overall length of the hole constant. The present study maintains the diffuser expansion angles and instead increases the length of the diffuser, which results in longer holes. Various area ratios have been examined for two shaped holes: one with forward and lateral expansion angles of 7° (7-7-7 hole) and one with forward and lateral expansion angles of 12° (12-12-12 hole). Each hole shape was tested at numerous blowing ratios to capture trends across various flow rates. Adiabatic effectiveness measurements indicate that for the baseline 7-7-7 hole, a larger area ratio provides higher effectiveness, especially at higher blowing ratios. Measurements also indicate that for the 12-12-12 hole, a larger area ratio performs better at high blowing ratios but the hole experiences ingestion at low blowing ratios. Steady RANS simulations did not accurately predict the levels of adiabatic effectiveness, but did predict the trend of improving effectiveness with increasing area ratio for both hole shapes. Flowfield measurements with PIV were also performed at one downstream plane for a low and high area ratio case, and the results indicate an expected decrease in jet velocity due to a larger diffuser.

scholarly journals Design of High-Area-Ratio Nozzle Contours Using Circular Arcs

2016 ◽  
Vol 32 (1) ◽  
pp. 188-195 ◽  
Author(s):  
K. Schomberg ◽  
J. Olsen ◽  
G. Doig
Keyword(s):  
Area Ratio ◽  
Circular Arcs ◽  
High Area

Hierarchical self-supported Ni(OH)2@Ni12P5 for supercapacitor electrodes with ultra-high area ratio capacitance

2021 ◽  
pp. 139605
Author(s):  
Jiang Liao ◽  
Ao Ju ◽  
Wenhao Jiang ◽  
Yan Ju ◽  
Xueliang Liu ◽  
...  
Keyword(s):  
Area Ratio ◽  
High Area ◽  
Supported Ni

Novel High Area Ratio T-Burner for Characterizing Metalized Propellants

1974 ◽  
Vol 11 (8) ◽  
pp. 574-578
Author(s):  
C. M. MlHLFEITH ◽  
L. H. SAYER
Keyword(s):  
Area Ratio ◽  
High Area

Effects of Area Ratio and Mean Rise Angle on the Aerodynamics of Inter-Turbine Ducts

2014 ◽  
Author(s):  
Yanfeng Zhang ◽  
Shuzhen Hu ◽  
Ali Mahallati ◽  
Xue-Feng Zhang ◽  
Edward Vlasic
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Computational Study ◽  
Pressure Rise ◽  
Adverse Pressure Gradient ◽  
Boundary Layer Separation ◽  
Area Ratio ◽  
Wake Flow ◽  
High Area ◽  
Inlet Swirl

The present work, a continuation of a series of investigations on the aerodynamics of aggressive inter-turbine ducts (ITD), is aimed at providing detailed understanding of the flow physics and loss mechanisms in four different ITD geometries. A systematic experimental and computational study was carried out for varying duct mean rise angles and outlet-to-inlet area ratio while keeping the duct length-to-inlet height ratio, Reynolds number and inlet swirl constant in all four geometries. The flow structures within the ITDs were found to be dominated by the counter-rotating vortices and boundary layer separation in both the casing and hub regions. The duct mean rise angle determined the severity of adverse pressure gradient in the casing’s first bend whereas the duct area ratio mainly governed the second bend’s static pressure rise. The combination of upstream wake flow and the first bend’s adverse pressure gradient caused the boundary layer to separate and intensify the strength of counter-rotating vortices. At high mean rise angle, the separation became stronger at the casing’s first bend and moved farther upstream. At high area ratios, a 2-D separation appeared on the casing. Pressure loss penalties increased significantly with increasing duct mean rise angle and area ratio.

Obtaining a high area ratio free-standing silicon microchannel plate via a modified electrochemical procedure

2008 ◽  
Vol 18 (3) ◽  
pp. 037003 ◽  
Author(s):  
Xiaoming Chen ◽  
Jilei Lin ◽  
Ding Yuan ◽  
Pengliang Ci ◽  
Peisheng Xin ◽  
...  
Keyword(s):  
Area Ratio ◽  
Microchannel Plate ◽  
Free Standing ◽  
High Area
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