Swirling Flow Through Annular Diffusers With Conical Walls

1979 ◽  
Vol 101 (2) ◽  
pp. 224-229 ◽  
Author(s):  
R. P. Lohmann ◽  
S. J. Markowski ◽  
E. T. Brookman
Keyword(s):  
Swirling Flow ◽  
Meridional Flow ◽  
Tangential Component ◽  
Meridional Velocity ◽  
Flow Swirl ◽  
Swirl Angle ◽  
Inlet Swirl ◽  
Flow Through ◽  
High Degree ◽  
Degree Of Similarity

The performance of a series of diffusers of various lengths, area ratios and cant angles was determined experimentally over a range of inlet flow swirl angles between axial and 48 degrees. The results indicate that increases in the inlet swirl angle and the cant angle, particularly in combination, lead to increased distortion of the meridional velocity profile at the diffuser exit. With a swirling throughflow separation occurs at the inner wall and is encountered at progressively lower area ratios as the inlet swirl angle is increased. The tangential component of the flow is relatively independent of the meridional flow in that the angular momentum is essentially conserved and a high degree of similarity is found in these profiles at the diffuser exit.

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.

scholarly journals The Development of Swirling Decaying Laminar Flow in an Annular Pipe

2018 ◽  
Vol 51 ◽  
pp. 03001
Author(s):  
Baiman Chen ◽  
Frank G.F. Qin ◽  
Youyuan Shao ◽  
Hanmin Xiao ◽  
Simin Huang ◽  
...  
Keyword(s):  
Turbulent Flows ◽  
Pipe Flow ◽  
Tangential Component ◽  
Duct Flow ◽  
Mean Flow ◽  
Entry Length ◽  
Swirl Angle ◽  
Practical Engineering ◽  
Inlet Swirl ◽  
Annular Pipe

Work on the hydrodynamic entry length of pipe and duct flow has been well studied over the years. The assumption of fully developed flows is commonly used in many practical engineering applications (e.g. Moody's chart). For laminar axial pipe flow, the hydrodynamic entry length can be found through the monomial proposed by Kays, Shah and Bhatti (KSB) (Lh=0.056ReDh). In contrast, several approximations exist for fully turbulent flows (i.e. 10Dh-150Dh). Through theoretical and numerical investigations, the hydrodynamic entry length for swirling decaying pipe flow in the laminar regime is investigated. It was found that, the development length Lh for the axial velocity profile changes when a tangential component is added to the mean flow. The reduction in the hydrodynamic length was found to be dependent on the inlet swirl angle θ. The results indicate that a modification can be made on the KSB equation for two-dimensional swirling annular pipe flow.

CFD Analysis of Circle Grid Fractal Plate Thickness on Turbulent Swirling Flow

2013 ◽  
Vol 465-466 ◽  
pp. 109-113 ◽  
Author(s):  
Bukhari Manshoor ◽  
Izzuddin Zaman ◽  
Mohamad Jaat ◽  
Amir Khalid
Keyword(s):  
Pressure Drop ◽  
Swirling Flow ◽  
Plate Thickness ◽  
Tangential Velocity ◽  
Flow Characteristics ◽  
Turbulent Model ◽  
Swirl Angle ◽  
Ansys Cfx ◽  
Flow Through ◽  
Different Thickness

In this paper, steady state, incompressible, swirling turbulent flow through circle grid fractal plate has been simulated. The aim of the simulation is to investigate an effect of the circle grid fractal plate thickness in order to reduce swirling due to swirl disturbance in pipe flow. The simulation and analysis were carried out using finite volume CFD solver ANSYS CFX. Three different thickness of fractal plate were used in the simulation work with the thickness of 1 mm, 3 mm and 6 mm. The simulation results were compared with the pressure drop correlation of BS EN ISO 5167-2:2003 and turbulent model used, standard k-ε model gave the best agreement with the ISO pressure drop correlation. The effects of circle grid fractal plate thickness on the flow characteristics which are swirl angle and tangential velocity have been investigated as well.

Effects of casing angle on the performance of parallel hub axial annular diffuser

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hardial Singh ◽  
B.B. Arora
Keyword(s):  
Static Pressure ◽  
Swirling Flow ◽  
Pressure Recovery ◽  
Recovery Coefficient ◽  
Pressure Loss Coefficient ◽  
Swirl Angle ◽  
Annular Diffuser ◽  
Inlet Swirl ◽  
Total Pressure Loss Coefficient ◽  
Pressure Recovery Coefficient

Abstract In this paper, the effects of non-swirling and swirling flow on the performance of parallel hub axial annular diffuser has been investigated. The study was conducted on a fully developed swirling flow and non-swirling flow to predict the separation of the flow from the wall. Three different annular diffusers were used with casing wall angles of 3°, 6°, and 9°. Furthermore, various swirl angles (0–25°) at the inlet of diffusers have been investigated to analyze the performance across the length. It was found that parallel hub axial annular diffuser performance increases up to a certain length as the inlet swirl angle increases. However, the performance also improves as the diffuser area ratio (AR) increases. The performance is evaluated based on the static pressure recovery coefficient (Cp) and the total pressure loss coefficient (CTL). The highest possible pressure recovery is achieved by the 12° swirl angle with a casing angle of 6°.

Strut Losses in a Diverging Annular Diffuser With Swirling Flow

2006 ◽  
Author(s):  
G. K. Feldcamp ◽  
A. M. Birk
Keyword(s):  
Total Pressure ◽  
Swirling Flow ◽  
Pressure Recovery ◽  
Swirl Number ◽  
Pressure Losses ◽  
Swirl Angle ◽  
Wide Range ◽  
Annular Diffuser ◽  
Inlet Swirl ◽  
The Ideal

An experimental investigation into the overall influence of struts spanning a double divergent annular diffuser followed by a straight cored annular diffuser has been undertaken in order to determine the performance of various strut configurations over a wide range of inlet swirl conditions. Two strut profiles have been investigated in four and eight strut configurations. Results have shown that the presence of struts under no swirl conditions have a relatively small effect on the overall total pressure loss. Increasing the inlet swirl angle to 20° has shown that the struts are able to assist in recovery of the swirling flow such that the pressure recovery nearly approaches that without struts, despite increased total pressure losses. Performance at 40° swirl is highly dependent on strut profile; the higher thickness-to-chord ratio strut configurations show minimal decrease in pressure recovery compared to 20° swirl, while the lower thickness-to-chord ratio configurations experiences a significant decrease as the result of significant flow separation from the struts. The exit swirl number has been shown to correlate strongly with the strut profile shape, while the number of struts had only a secondary influence. The exit velocity profiles show significant distortions at 40° swirl, and as a result the ideal pressure recovery calculated from the inlet and exit profiles change with strut configuration at 40° swirl.

Effects of Scalloping on the Mixing Mechanisms of Forced Mixers With Highly Swirling Core Flow

2012 ◽  
Author(s):  
Alex Wright ◽  
Zhijun Lei ◽  
Ali Mahallati ◽  
Mark Cunningham ◽  
Julio Militzer
Keyword(s):  
Swirling Flow ◽  
Separation Bubble ◽  
Three Dimensional ◽  
Suction Surface ◽  
Reduced Pressure ◽  
Core Flow ◽  
Pressure Losses ◽  
Swirl Angle ◽  
Inlet Swirl ◽  
Mixing Rates

This paper presents a detailed experimental and computational investigation of the effects of scalloping on the mixing mechanisms of a scaled 12-lobe turbofan mixer. Scalloping was achieved by eliminating approximately 70% of the lobe sidewall area. Measurements were made downstream of the mixer in a co-annular wind tunnel and the simulations were carried out using an unstructured RANS solver, Numeca FINE/Hexa, with k-ω SST model. In the core flow, the swirl angle was varied from 0° to 30°. At high swirl angles, a three-dimensional separation bubble was formed on the lobe’s suction surface penetration region and resulted in the generation of a vortex at the lobe valley. The valley vortex quickly dissipated downstream. Most of the swirl was removed by the lobes, but scalloping allowed residual swirl to persist downstream of the mixer. The interaction of the swirling flow and the vortices resulted in improved mixing rates for the scalloped mixer. Inlet swirl up to 10° provided improved mixing rates, reduced pressure loss and thrust loss for both mixers. High inlet swirl resulted in improved mixing but produced higher pressure and thrust losses as compared to the zero swirl case. At high swirl, the scalloped mixer resulted in better mixing and lower pressure losses than the unscalloped mixer, but at the expense of reduced thrust.

scholarly journals Effects of casing angle on the performance of parallel hub axial annular diffuser

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hardial Singh ◽  
B.B. Arora
Keyword(s):  
Static Pressure ◽  
Swirling Flow ◽  
Pressure Recovery ◽  
Recovery Coefficient ◽  
Pressure Loss Coefficient ◽  
Swirl Angle ◽  
Annular Diffuser ◽  
Inlet Swirl ◽  
Total Pressure Loss Coefficient ◽  
Pressure Recovery Coefficient

AbstractIn this paper, the effects of non-swirling and swirling flow on the performance of parallel hub axial annular diffuser has been investigated. The study was conducted on a fully developed swirling flow and non-swirling flow to predict the separation of the flow from the wall. Three different annular diffusers were used with casing wall angles of 3°, 6°, and 9°. Furthermore, various swirl angles (0–25°) at the inlet of diffusers have been investigated to analyze the performance across the length. It was found that parallel hub axial annular diffuser performance increases up to a certain length as the inlet swirl angle increases. However, the performance also improves as the diffuser area ratio (AR) increases. The performance is evaluated based on the static pressure recovery coefficient (Cp) and the total pressure loss coefficient (CTL). The highest possible pressure recovery is achieved by the 12° swirl angle with a casing angle of 6°.

scholarly journals The Development of Swirling Decaying Laminar Flow in an Annular Pipe

2018 ◽  
Vol 51 ◽  
pp. 03001
Author(s):  
Baiman Chen ◽  
Frank G.F. Qin ◽  
Youyuan Shao ◽  
Hanmin Xiao ◽  
Simin Huang ◽  
...  
Keyword(s):  
Turbulent Flows ◽  
Pipe Flow ◽  
Tangential Component ◽  
Duct Flow ◽  
Mean Flow ◽  
Entry Length ◽  
Swirl Angle ◽  
Practical Engineering ◽  
Inlet Swirl ◽  
Annular Pipe

Work on the hydrodynamic entry length of pipe and duct flow has been well studied over the years. The assumption of fully developed flows is commonly used in many practical engineering applications (e.g. Moody's chart). For laminar axial pipe flow, the hydrodynamic entry length can be found through the monomial proposed by Kays, Shah and Bhatti (KSB) (Lh=0.056ReDh). In contrast, several approximations exist for fully turbulent flows (i.e. 10Dh-150Dh). Through theoretical and numerical investigations, the hydrodynamic entry length for swirling decaying pipe flow in the laminar regime is investigated. It was found that, the development length Lh for the axial velocity profile changes when a tangential component is added to the mean flow. The reduction in the hydrodynamic length was found to be dependent on the inlet swirl angle θ. The results indicate that a modification can be made on the KSB equation for two-dimensional swirling annular pipe flow.

Flow Investigations on Swirling Compressible Flow Through a Vaneless Radial Diffuser

1987 ◽  
Author(s):  
D. P. Agrawal ◽  
S. M. Yahya ◽  
D. N. Reddy
Keyword(s):  
Mach Number ◽  
Compressible Flow ◽  
Performance Parameters ◽  
Flow Angle ◽  
Swirl Generator ◽  
Swirl Angle ◽  
Inlet Swirl ◽  
Flow Through ◽  
Swirl Vane ◽  
Nozzle Type

The present study deals with the experimental investigation of Swirling compressible flow through a parallel walled vaneless radial diffuser. Swirl generator of vortex nozzle type is used for supplying swirling compressible flow at the diffuser inlet up to a Mach number of 0.8. The desired flow angles are achieved by adjusting inlet swirl vane setting angles from 2.5° to 12.5°. The results are presented in terms of performance parameters such as pressure recovery and loss coefficient for various diffuser inlet Mach numbers from 0.3 to 0.8 and flow angle range from 20° to 35°. The effect of Mach number and swirl angle on the performance of the vaneless radial diffuser are discussed.

scholarly journals Effect of swirl flow on the performance of parallel hub axial annular diffuser

2021 ◽  
Author(s):  
Hardial Singh ◽  
◽  
Arora B.B ◽  
Keyword(s):  
Swirling Flow ◽  
Cone Angle ◽  
Axial Flow ◽  
Swirl Flow ◽  
Recovery Coefficient ◽  
Pressure Loss Coefficient ◽  
Swirl Angle ◽  
Annular Diffuser ◽  
Inlet Swirl ◽  
Result Analysis

In the present work, the parallel hub axial flow annular diffuser's performance characteristics with divergent casing varying between equivalent cone angle (10°, 15°, and 20°) with area ratio 3 have been evaluated computationally as well as experimentally. The performance of three diffusers were tested at different inlet swirl angles (from 0° to 25°) for swirling and non-swirling flow. Simulations have been carried out on a fully developed flow at Reynolds number 2.5×105. The results were analyzed based on the velocity profiles, static pressure recovery coefficient, and the total pressure loss coefficient. The result analysis shows that the inlet swirl flow improves the recovery of pressure and also delays the flow separation on the casing. Moreover,the findings also show that the best performance was achieved in equivalent cone angle 10° at the inlet swirl angle of 7.5° compared to other diffusers.

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