Experimental and CFD Study of an Exhaust Ejector With Round Entraining Diffuser

2007 ◽  
Author(s):  
Qi Chen ◽  
A. M. Birk
Keyword(s):  
Computational Study ◽  
Flow Temperature ◽  
Primary Flow ◽  
Flow Rates ◽  
Wall Functions ◽  
Experimental Configuration ◽  
Swirl Angle ◽  
Inlet Swirl ◽  
Air Ejector ◽  
Velocity Pressure

This paper presents experimental and CFD data for the performance of a round straight air-air ejector with a 4-ring entraining diffuser. The effects of inlet swirl angle and flow temperature on the ejector pumping, back pressure, wall pressure distribution, and diffuser pressure recovery were studied. The ejector experiments were carried out on a hot flow wind tunnel that can provide primary flow rates up to 2.2 kg/s at ambient temperature and 1.8 kg/s at 500°C. Velocity, pressure and temperature measurements were taken in the annulus upstream of the primary nozzle, on the mixing tube and diffuser walls, and at the mixing tube and diffuser ring exits. A parallel computational study was conducted along with the experimental study. A commercial CFD solver, Fluent 6.216, was used for simulation. The Realizable k-ε turbulence model and non-equilibrium wall functions were implemented on the cases. The CFD inlet boundary conditions were chosen to replicate the experimental configuration.

Performance of a Round Ejector With 22.5° Bent Entraining Diffuser

2010 ◽  
Author(s):  
Qi Chen ◽  
A. M. Birk
Keyword(s):  
Outer Side ◽  
Similar Data ◽  
Flow Temperature ◽  
Flow Rates ◽  
Hot Gas ◽  
Flow Swirl ◽  
Swirl Angle ◽  
Mass Flow Rates ◽  
Core Cooling ◽  
Velocity Pressure

This paper presents experimental data for the performance of a round ejector with a 22.5° bent entraining diffuser. The experiments were carried out on a hot gas wind tunnel that could provide primary mass flow rates up to 2.2 kg/s at ambient temperature and 1.8 kg/s at 500°C. Velocity, pressure and temperature were measured in the annulus upstream of the primary nozzle, on the mixing tube and diffuser walls, at the diffuser gap inlets and at the diffuser exit. The inlet flow swirl angle and flow temperature were varied to study their effect on ejector pumping, wall pressure, and wall temperature distribution. The data from bent ejectors were compared with similar data for a round straight ejector. The results showed that the 22.5° bent entraining ejector had better hot core cooling performance than the straight entraining ejector since the hot core was cooled by the tertiary flow more efficiently at the outer side of the bend.

Experimental Study of an Exhaust Ejector With Entraining Diffuser

2005 ◽  
Author(s):  
Qi Chen ◽  
A. M. Birk
Keyword(s):  
Gas Turbine ◽  
Exhaust System ◽  
Industrial Applications ◽  
Area Ratio ◽  
Pressure Recovery ◽  
Entrainment Ratio ◽  
Wide Range ◽  
Inlet Swirl ◽  
Air Ejector ◽  
Velocity Pressure

Air-air ejectors are used in a wide range of industrial applications. In gas turbine installations, ejectors are typically used for entraining ventilation air or cooling of exhaust ducting. In some gas turbine applications, the exhaust system must be cooled to limit temperatures inside the structure or to manage heat signatures. The ducts are usually cooled by ejectors with film or effusion cooled diffusers. Entraining diffusers typically have poor pressure recovery and as a result, the ejector performance is affected. This paper presents experimental results on the performance of an air-air ejector with an entraining diffuser. The effects of inlet swirl, and primary nozzle area ratio on the diffuser pressure recovery and ejector pumping were studied. The ejector experiments were carried out on a cold flow wind tunnel that can provide primary air flow rates up to 2.2 kg/s at ambient temperature. Velocity, pressure and temperature measurements were taken in the annulus upstream of the primary nozzle, at the nozzle exit, at the diffuser inlet, on the diffuser walls, and at the diffuser exit. The results show that swirl strongly improves flow non-uniformity at the diffuser exit. The peak pumping performance and the strongest diffuser gap flows was observed with 20° of swirl in the primary nozzle flow. At the no swirl condition, the nozzle area ratio slightly affected the overall entrainment ratio. However, the large nozzle area ratio resulted in the best pumping when swirl was applied.

Experimental Study of Oblong Exhaust Ejectors With Multi-Ring Oblong Entraining Diffusers

2008 ◽  
Author(s):  
Qi Chen ◽  
A. M. Birk
Keyword(s):  
Film Cooling ◽  
Surface Film ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Hot Gas ◽  
Swirl Angle ◽  
Inlet Swirl ◽  
Mass Flow Rates ◽  
Overall Performance ◽  
Velocity Pressure

This paper presents experimental data for the performance of two oblong, straight, air-air ejectors with 4-ring oblong entraining diffusers. The effects of inlet swirl angle, nozzle diameter and flow temperature on the ejector pumping, back pressure, wall pressure distribution, diffuser pressure recovery and surface film cooling effectiveness were studied. The experiments were carried out on a hot gas wind tunnel that could provide primary mass flow rates up to 2.2 kg/s at ambient temperature and 1.8 kg/s at 500°C. Velocity, pressure and temperature were measured in the annulus upstream of the primary nozzle, on the mixing tube and diffuser walls, at the diffuser gap inlets and at the diffuser exit. A comparison between the performance of the oblong ejector and a round ejector indicated that for a short length ejector, the oblong ejector provided better overall performance in terms of pumping and velocity and temperature distributions.

Experimental and Computational Evaluation of an Ejector System Utilizing a Primary S-Bend Transition Duct

2004 ◽  
Author(s):  
J. C. Mateer ◽  
A. M. Birk ◽  
D. Poirier
Keyword(s):  
Turbulence Modeling ◽  
Computational Study ◽  
Flow Measurements ◽  
Wall Functions ◽  
Cold Flow ◽  
Aerospace Applications ◽  
Computational Evaluation ◽  
Experimental Apparatus ◽  
Ejector System ◽  
Air Ejector

An experimental and computational study of an air-air ejector system applicable to aerospace applications was conducted. The geometry of the ejector consists of a primary S-bend duct that expels into an oblong mixing tube. The focus of this study was to determine the performance and practicality of an ejector implemented downstream of an S-bend duct. Experimental and computational results were compared to determine computational adequacy. The experimental apparatus utilized a cold flow blower delivering air through an annulus to an S-bend duct that incorporated a downstream mixing tube. Flow measurements were made at the inlet and outlet of the duct as well as at the outlet of the mixing tube. This allowed losses of the primary duct as well as ejector pumping performance to be evaluated. The computational work involved using a commercial CFD package implementing k-ε turbulence modeling and non-equilibrium wall functions.

Experimental Study of Oblong Exhaust Ejectors With Multiring Oblong Entraining Diffusers

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Qi Chen ◽  
A. M. Birk
Keyword(s):  
Film Cooling ◽  
Surface Film ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Hot Gas ◽  
Swirl Angle ◽  
Inlet Swirl ◽  
Mass Flow Rates ◽  
Overall Performance ◽  
Velocity Pressure

This paper presents experimental data for the performance of two oblong, straight, air-air ejectors with four-ring oblong entraining diffusers. The effects of inlet swirl angle, nozzle diameter, and flow temperature on the ejector pumping, backpressure, wall pressure distribution, diffuser pressure recovery, and surface film cooling effectiveness were studied. The experiments were carried out on a hot gas wind tunnel that could provide primary mass flow rates up to 2.2kg∕s at ambient temperature and 1.8kg∕s at 500°C. Velocity, pressure, and temperature were measured in the annulus upstream of the primary nozzle, on the mixing tube and diffuser walls, at the diffuser gap inlets, and at the diffuser exit. A comparison between the performance of the oblong ejector and a round ejector indicated that for a short length ejector, the oblong ejector provided better overall performance in terms of pumping and velocity and temperature distributions.

Computational Comparison of an Air-Air Ejector System Utilizing a Primary S-Bend Transition Duct Employing the Realizable k-ε Turbulence Model

2005 ◽  
Author(s):  
J. C. Mateer ◽  
A. M. Birk ◽  
D. Poirier
Keyword(s):  
Turbulence Model ◽  
Computational Study ◽  
Back Pressure ◽  
Experimental Results ◽  
Tube Length ◽  
Complex Flow ◽  
Inlet Swirl ◽  
Ejector System ◽  
Inlet Conditions ◽  
Air Ejector

A computational study of an air-air ejector system, utilizing a primary S-bend transition duct, was compared with experimental results. Two primary ducts, differing in offset, consisted of an annular-to-circular-to-oblong transition which incorporated a total area increase of 62.4% with the duct performing 16% diffusion. The ducts were analyzed both alone and in ejector configuration under varying degrees of inlet swirl. The ejector geometry consisted of the duct with a downstream mixing tube. Several mixing tubes, of oblong cross sectional shape, differing in both length and area, were tested in various parametric configurations. Ejector performance was established on the basis of pumping capability, duct back pressure, and outlet effective area. Experimental work commenced on a cold flow test rig, with duct inlet conditions being measured with four 3-hole pitot probes. The duct outlet profiles were measured using a 7-hole probe which traversed the entire exit area. Three conditions of inlet swirl were analyzed: 0°, 20° and 40°. Experimental results showed an increase in pumping performance with increased inlet swirl, mixing tube length, area ratio and standoff. An optimum standoff value of 0.25Dh2 was observed. CFD simulations were based on experimental mass flow inlet conditions utilizing the realizable k-ε turbulence model. CFD results showed that the realizable k-ε turbulence model was quite capable of modeling the complex flow for the associated geometry, and correctly predicted flow features as well as performance trends for all geometrical configurations tested. However, the CFD was unable to properly predict the duct inlet static pressure leading to erroneous back pressure results.

Computational Study of a Two-Passage Turbine Guide-Vane Cascade With End-Wall Contouring

2001 ◽  
Author(s):  
Bin Zhu ◽  
Yu-Liang Lin ◽  
Tom I-P. Shih ◽  
Rohit Oke ◽  
Terry W. Simon ◽  
...  
Keyword(s):  
Stokes Equations ◽  
Computational Study ◽  
Guide Vane ◽  
Turbulence Models ◽  
Leading Edge ◽  
Experimental Setup ◽  
Flow Rates ◽  
Wall Functions ◽  
Linear Cascade ◽  
Periodic Linear

Abstract CFD simulations based on the ensemble-averaged compressible Navier-Stokes equations, closed by two different turbulence models — the standard k-ε model with wall functions and the two-layer model of Chen and Patel — were performed to guide the design of a two-passage experimental setup, which models a linear cascade by using only three airfoils. Results generated show that the angle of the tailboards can be adjusted to give the same flow rates through the two passages. Results also show that once the flow rates are nearly the same, the pressure distributions become nearly periodic, indicating that the two-passage experimental setup does indeed mimic a linear cascade. The discrepancies between the two-passage experimental setup and a truly periodic linear cascade include the location of the stagnation zone about the airfoil’s leading edge and the shape of the pressure distribution in the trailing-edge region.

Performance characteristics of flow in annular diffuser using CFD

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hardial Singh ◽  
Bharat Bhushan Arora
Keyword(s):  
Swirling Flow ◽  
Flow Behavior ◽  
Pressure Recovery ◽  
Ansys Fluent ◽  
Pressure Loss Coefficient ◽  
Swirl Angle ◽  
Swirl Intensity ◽  
Annular Diffuser ◽  
Inlet Swirl ◽  
Total Pressure Loss Coefficient

Abstract An annular diffuser is a critical component of the turbomachinery, and its prime function is to reduce the flow velocity. The current work is carried to study the effect of four different geometrical designs of an annular diffuser using the ANSYS Fluent. The numerical simulations were carried out to examine the effect of fully developed turbulent swirling and non-swirling flow. The flow behavior of the annular diffuser is analyzed at Reynolds number 2.5 × 105. The simulated results reveal pressure recovery improvement at the casing wall with adequate swirl intensity at the diffuser inlet. Swirl intensity suppresses the flow separation on the casing and moves the flow from the hub wall to the casing wall of the annulus region. The results also show that the Equal Hub and Diverging Casing (EHDC) annular diffuser in comparison to other diffusers has a higher static pressure recovery (C p  = 0.76) and a lower total pressure loss coefficient of (C L  = 0.12) at a 17° swirl angle.

Effects of Area Ratio and Mean Rise Angle on the Aerodynamics of Interturbine Ducts

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Yanfeng Zhang ◽  
Shuzhen Hu ◽  
Ali Mahallati ◽  
Xue-Feng Zhang ◽  
Edward Vlasic
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Static Pressure ◽  
Computational Study ◽  
Pressure Rise ◽  
Adverse Pressure Gradient ◽  
Boundary Layer Separation ◽  
Wake Flow ◽  
Height Ratio ◽  
Inlet Swirl

This work, a continuation of a series of investigations on the aerodynamics of aggressive interturbine 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 by varying duct outlet-to-inlet area ratios (ARs) and mean rise angles 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 boundary layer separation and counter-rotating vortices 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 AR 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 ARs, a two-dimensional separation appeared on the casing and resulted in increased loss. Pressure loss penalties increased significantly with increasing duct mean rise angle and AR.

Analysis of the Vortex Series Around Tabs in the Bent Marine Exhaust Ejector

2017 ◽  
Author(s):  
Aoyu Ren ◽  
Hai’ou Sun ◽  
Zhongyi Wang ◽  
Xudong Chen
Keyword(s):  
High Performance ◽  
Streamwise Vortex ◽  
Streamwise Vorticity ◽  
Gas Temperature ◽  
Cross Sectional ◽  
Swirl Angle ◽  
Calculation Results ◽  
Inlet Swirl ◽  
Hybrid Grid ◽  
Tube Exit

In order to facilitate the application of special structural ejectors, which improve the ability of pumping the secondary flow without additional power consumption, reducing the flue gas temperature at the export and enhancing the ship viability under the threat of infrared guided weapons, this paper regardes the 90 ° bend tabs ejector as the research object according to the actual situation of our country’s ships, focuses on the inner effect of the existence of tabs on the flow field in the bent channel, and mainly revealed the transformation of the vortex around the tabs, for providing an explanation to a certain extent about how the tabs affect the macro performance of ejector. With ANSYS software, ring 8 equilateral triangles tabs were designed with 120 ° wall surface mounting angle. With adjusting the blocking ratio of the main outlet area based on the similar zoom, setting inlet swirl angle, and building a hybrid grid to compute, the vortex structure distribution and the development around tabs were observed. The maximum vorticity of vortex at different distances in the mixing tube to the mix tube exit had been calculated to reflect the change of vortex intensity. The final results show that although the streamwise vortices are still located in an axial symmetrical distribution, the swirl angle leads to an uneven distribution of the flow on both sides of a single tab. The inlet swirl angle can make the symmetry of the steamwise vortex vaguer, but the effect of the convection to the vortex is enhanced. The blocking area ratio of the nozzle cross-sectional surface has a large effect on the vorticity of the streamwise vortex. The calculation results show that the larger the blocking area is, the greater the vorticity of streamwise vortex is, which also shows that when the tab shape is fixed, the tab surface area will increase the streamwise vorticity. Through the above research, the shape and the change of the streamwise vortex generated by the tabs in the bent ejector are clearly demonstrated, which can be a reference for the design of high performance bent ejector.

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