International Journal on Mechanical Engineering and Robotics (IJMER)
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Analysis of Fluid Structure Interaction in Mixing Fluids
1
A. Eswara Kumar, 2Naveen Janjanam, 3Nagaraju.M & 4Diwakar. V
1,2
Dhanekula Institute of Engineering & Technology1,3,4K L University
Email: [email protected], [email protected]
Abstract - Typically power plant especially at condensers
contains many junctions to mix hot and cold fluids. The
effectiveness of mixing will depends on the type of the
mixing chamber, velocity or mass flow rate of the fluids
and turbulence intensity. This stage plays a major role to
effectively utilize the energy of the hot fluids. In this study,
the effect of velocities of hot and cold fluids, Temperatures
of hot and cold fluids on outlet temperature, outlet velocity,
outlet turbulence kinetic energy, total deformation of
structure and von mises stress for selected mixing chamber
are observed,
Index Terms —Fluid structure interaction; Turbulence
kinetic energy; Ansys cfx; One way fluid structure
interaction.
I. INTRODUCTION
In most power plants mixing of hot and cold fluids is
very common process. To utilize the enthalpy of the hot
fluids, generally this mixing phenomenon will be
existed. The effectiveness of the mixing will be typically
depends on the type of the fluids, type of the chamber
used to mix the fluids, mass flow rate of the fluids and
turbulence of the fluids. In pressure applications after
mixing they will exert pressure on the wall of the
structure due to the convergent or divergent mixing
chambers. It is also necessary to know the deformation
and stresses produced in the structure to avoid the
bursting of the pipes.
Elmabruk et al [1] investigated the mixing efficiency of
single T-junction and double T junction having
rectangular cross sections and conclude that double Tjunction has higher mixing efficiency. Gianni et al [2]
performed the mixing of ethanol-water, water-water at
two Reynolds numbers (100, 230) and showed that at
lower Reynolds’s number mixing of water-ethanol is
better than water-water. Achouri et al [3] observed the
effect of fluid viscosity in a stirred tank with Rushton
turbine. They changed the viscosity by adding the
carbon methyl cellulose. Venkateswara Rao et al [4]
performed the 2-D analysis for mixing of hot and cold
fluids by placing the nozzle at two different locations in
Ansys fluent software. Linling et al [5] observed the
sensitivity of mixing fluids by changing the Reynolds’s
number and Richardson number in axial pipe lines.
Dular et al [6] predicted the different features of non-
Newtonian fluids mixing process by selecting simple
impeller for mixing of carboxymethyl cellulose. They
observed the vortex formation above the impeller.
Gianni et al [7] observed the mixing dynamics of two
miscible fluids with in a T-shaped micro mixer for
water-water case and water-ethanol case. They said that
at lower Reynolds’s number there is no vortex
formation.
II. PROBLEM STATEMENT
The objective of the work is to study the effectiveness of
the mixing fluids and response of the pipe in which the
fluids are flowing by changing the input parameters. The
mixing fluid is used in this case is water which is cold at
the inlet 1 and hot at the inlet 2,3 as shown in the Fig 1.
The inlet parameters include velocities of inlet 1, 2, 3
and temperatures of inlet 1, 2, 3. The output parameters
include outlet temperature, outlet velocity, outlet
turbulence kinetic energy, total deformation and von
mises stress.
The design of the structure is modelled in Ansys
workbench 12 version. It contains totally 3 inlets and
one outlet. Cold fluid flows through the inlet 1 and hot
fluid flows through the inlet 2,3
Fig 1: Model of the geometry
All these will mix in the mixing chamber. In Fig. 1 the
green color indicates fluid region and remaining volume
is pipe lines made of structural steel. The total analysis
contains two parts, out of which one is fluid analysis in
this output parameters of fluid flow will be examined
and other part is structure part. In this pressure from
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ISSN (Print) : 2321-5747, Volume-3, Issue-3,2015
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International Journal on Mechanical Engineering and Robotics (IJMER)
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fluid analysis is imported into the structural analysis and
response of the structure will be examined.
A. Meshing
It is the process of converting the geometrical entities
into elements and nodes. Both fluid region and solid
region are meshed with fine mesh to get the meshing
convergence. Higher order tetrahedron element is used
to mesh the volumes.
Fig 2: Meshing of the fluid region
III. RESULTS & DISCUSSIONS
A. Contours
Fig 7 shows the typical diagram how mixing is
happening in the chamber. It can be observed that, a
proper mixing is happening in the mixing chamber. All
the inlets having the same velocity and after mixing the
outlet velocity changes as shown in Fig 7.
Fig 3: Meshing of solid region
A. Loads and boundary conditions
Fig 7: Mixing phenomenon
Fig 8 shows response of the solid region in the view of
total deformation and von mises stress. The deformation
and von mises stress is higher in the mixing chamber.
The inlet-1 temperature is taken as 27oC and inlet 2, 3
temperatures are as 100oC in fluid analysis. For solid
regions all the inlet and outlet cross sections are fixed as
shown in Fig 4. The imported pressure is applied on the
inner face of the solid region as shown in Fig 6.
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Turbulence kinetic
energy
12
10
8
6
4
2
0
Fig 8: Total deformation
0
20
40
Velocity of inlet 2,3
Total deformation
Figure 10c: Variation of outlet T.K.E w.r.t velocity of
inlet 2,3
1.2
1
0.8
0.6
0.4
0.2
0
0
20
40
Velocity of inlet 2,3
Figure10d: Variation of total deformation w.r.t velocity
of inlet 2,3
Fig 9: Von mises stress
Von mises stress
100
90
80
70
60
0
20
0
20
40
40
Figure 10e: Variation of von mises stress w.r.t velocity
of inlet 2,3
Velocity of Inlet 2,3
Fig. 10a. Variation of outlet tempeature w.r.t velocity of
inlet 2,3
Outlet Velocity
350
300
250
200
150
100
50
0
Velocity of inlet 2,3
80
70
60
50
40
30
20
10
0
0
20
40
Outlet temperature
Outlet temperature
B. Graphs
100
90
80
70
60
0
20
40
Velocity of inlet 1
Fig. 11a. Variation of outlet tempeature w.r.t velocity of
inlet 1
Velocity of inlet 2,3
Figure 10b: Variation of outlet velocity w.r.t velocity of
inlet 2,3
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80
70
60
50
40
30
20
10
0
0
20
40
Outlet temperature
Outlet velocity
International Journal on Mechanical Engineering and Robotics (IJMER)
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120
100
80
60
40
40
12
10
8
6
4
2
0
40
Velocity of inlet 1
Figure 12a: Variation of outlet temperature w.r.t
temperature of inlet 2,3
Outlet temperature
Turbulence kinetic
energy
Figure 11b: Variation of outlet velocity w.r.t velocity of
inlet 1
20
140
Temperture of inlet 2,3
Velocity of inlet 1
0
90
120
115
110
105
100
0
50
100
Temperture of inlet 1
Total deformation
Figure 11c: Variation of outlet T.K.E w.r.t velocity of
inlet 1
Figure 12b: Variation of outlet temperature w.r.t
temperature of inlet 1
1.2
1
0.8
0.6
0.4
0.2
0
0
20
40
Velocity of inlet 1
Von mises stress
Figure 11d: Variation of total deformation w.r.t velocity
of inlet 1
350
300
250
200
150
100
50
0
From the above figure it can be observed that as the
velocity of the inlet 2, 3 increases, the outlet
temperature, out- let velocity, turbulence kinetic energy,
total deformation and von mises stress are also
increasing. These are shown in Fig 10a to 10e. As the
velocity of the inlet 1 is increasing, the outlet
temperature is decreasing but outlet velocity, turbulence
kinetic energy, total deformation and von mises stress
are increasing as shown in Fig. 11a to 11e. As the
temperature of the inlet 2, 3 is increasing, the outlet
temperature is increasing as shown in Fig. 12a, but
remaining parameters does not effected. As the
temperature of the inlet 1 is increasing, the outlet
temperature is increasing, but remaining parameters are
not effected as shown in Fig 12b.
IV. CONCLUSIONS
0
20
40
Velocity of inlet 1
Figure 11e: Variation of von mises stress w.r.t velocity
of
inlet 1
From the above observations it can be concluded that as
the velocities of the inlet 2, 3 increases, the outlet
temperature, velocity, T.K.E, total deformation and von
mises are increasing. As the velocity of the inlet 1
increases except outlet temperature, remaining output
parameters are increased. As the temperatures of the
inlet 1, 2, 3 are increasing, only outlet temperature is
increasing and remaining parameters are not affected.
The application where outlet temperature is required as
high, then increase the inlet temperatures and inlet
velocities.
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International Journal on Mechanical Engineering and Robotics (IJMER)
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simulation of hot and cold fluid mixing in T-pipe
by placing nozzle at different places”,
International journal of research in engineering
and technology, Vol.03,Issue 09.
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