Showing posts with label Flow. Show all posts
Showing posts with label Flow. Show all posts

Sunday 22 March 2020

Hypersonic Flow over a Two Dimensional Heated Cylinder

     This post is about the simulation of hypersonic flow over a heated circular cylinder, in two dimensions.

     Equation 1 is used as a relationship between Mach and the Reynold number.

M= Re*μ*√(R*T) ÷ d*P*√γ     (1)

     w.r.t. equation 1, the parameters represent the following quantities.

     M     Freestream Mach number at 17.6
     Re    Reynolds number at 376,000
     μ     Dynamic viscosity at 1.329045e-5 Ns.m-2
     R     Specific gas constant at 286.9 J.(kg.K)-1
     T     Freestream temperature 200 K
     d     Cylinder diameter at 5.6730225e-4 m
     P     Freestream pressure at 101325 Pa
     γ     Specific heat ratio at 1.4
     Tw  Wall temperature of cylinder at 500 K
     Pr    Prandtl number at 0.736

     The boundary conditions were taken from [1]. A comparison with [1] is shown in Fig. 1. Inside Fig. 1, the red dotted line with circles represents the data from [1]. The black solid line represents the data from the present simulation. Within Fig. 1, 0° represents the stagnation point. The velocity, pressure, Mach number and temperature contours are shown in Fig. 2.


Fig. 1 A comparison with previous research [1].


Fig. 2, Top Row, L-R: Velocity and pressure contours. Bottom Row, L-R: Mach number and temperature contours.

The computational mesh and the computational domain with boundary conditions visible are shown in Fig. 3-4, respectively. The computational domain had a size of 20D x 20D. The mesh had 836,580 total cells and 944 cells were located at the solid fluid boundary. Several local mesh controls were employed to capture the shockwave properly.


Fig. 3, The computational mesh.


Fig. 4, The computational domain.

     The solution method is Finite Volume method. SIMPLE-R is the solver employed. Implicit central difference scheme for diffusion terms, second-order Upwind scheme for convective terms and first-order implicit for temporal terms are used. The mesh created uses the Cartesian mesh with Immersed Boundary method.


     Reference:

     Thank you for reading. If you would like to collaborate on research projects, please reach out. I am looking for a PhD position, any guidance would be appreciated.

Monday 17 March 2014

Comparison between Down-Force and Drag Produced by a Legacy Spoiler VS a Spoiler with Tubercles (Humpback Whale Fin's Inspired)

Following data was obtained from Simulations carried out in SolidWorks Flow Simulation Premium.

Without Bumps

Air Speed in Km/h

Down Force in N

Drag in N

120
98.682
33.234
110
82.88
27.957
100
68.266
23.02
90
55.299
18.668
80
43.529
14.697
70
33.284
11.255
60
24.438
8.272
50
16.982
5.769
40
10.83
3.688
30
6.08
2.081
20
2.681
0.929
10
0.648
0.235


With Bumps

Air Speed in Km/h

Down Force in N

Drag in N

120
108.238
30.47
110
90.599
25.549
100
74.818
21.047
90
60.423
17.014
80
47.695
13.443
70
36.441
10.27
60
26.682
7.532
50
18.504
5.228
40
11.82
3.352
30
6.613
1.886
20
2.909
0.841
10
0.685
0.211

Comparison between Down Force and Drag

Air Speed in Km/h
Percentage Less Drag
Percentage More Down Force
120
8.32
8.83
110
8.61
8.51
100
8.57
8.76
90
8.86
8.48
80
8.53
8.73
70
8.75
8.66
60
8.95
8.41
50
9.38
8.23
40
9.11
8.38
30
9.37
8.06
20
9.47
7.84
10
10.21
5.4





It is clear that the spoiler with humpback whale's fin's inspired profile not only produce more down force at a particular velocity but also less drag.

Data for Spoiler without Humpback Whale's Fin's Inspired Bumps:

Wing Span: 100 cm
Chord Length: 17.5 cm
Air Velocity: 0-120 Km/h head on
Vertical Pitch: 22.5 Degree Downwards
Gravity Considered
Fluid: Dry Air at STP
Mesh Settings: Coarse (3/10)


Data for Spoiler with Humpback Whale's Fin's Bumps:

Wing Span: 100 cm
Chord Length Large: 17.5 cm
Chord Length Small: 15.75 cm
Air Velocity: 0-120 Km/h head on
Vertical Pitch: 22.5 Degree Downwards
Gravity Considered
Fluid: Dry Air at STP
Mesh Settings: Coarse (3/10)



Let's now take a look at visual representation of data.


This Plot Shows Air Velocity VS Drag, Down-Force by the Spoiler without Bumps


This Plot Shows Air Velocity VS Drag, Down-Force by the Spoiler with Bumps

As you can see from above two plots; the spoiler with the whale's fin like profile generates more down force and less drag.



This Plot Shows Air Velocity VS Down-Force Generated by the Spoilers

The green line represents the Down-Force generated by the spoiler with whale's fin's inspired design. It is around eight percent more at each velocity.


This Plot Shows Air Velocity VS Drag Generated by the Spoilers

The green line represents the Drag generated by the spoiler with whale's fin inspired design. It is around nine percent less at each velocity.


This Plot Shows Air velocity VS Down-Force to Drag Ratio

It is clear from this plot that Down-Force to Drag ratio is around sixteen percent more for whale's fin's inspired spoiler than the legacy one at each velocity.



This Plot Shows Air Flow Around the Spoiler without Bumps at 120 Km/h from the Right Side.


This Plot Shows Air Flow Around the Spoiler without Bumps at 120 Km/h.


This Plot Shows Air Flow Around the Spoiler with bumps at 120 Km/h.


This plot Shows Air Flow Around the Spoiler with bumps at 120 Km/h.

A simple stress analysis was carried out on both spoilers at 120 Km/h. FOS was greater than 1 for both cases.

Advantages of Spoilers:

The main benefit of installing a spoiler on a car is to help it maintain traction at very high speeds. Particularly at speeds around 90 Km/h. A car with a spoiler installed will be easier to handle at highway speeds. Rear spoilers such as the one's analysed in this study; push the back of the car down so the tires can grip the road better and increase stability. It also increases the braking ability of the car.

To build the prototypes and complete the study further, I need donations. To donate your part send an email to fadoobaba@live.com , tweet @fadoobaba, PM at https://www.facebook.com/ThreeDimensionalDesign orhttps://grabcad.com/fahad.rafi.butt or comment with your contact details and I will contact you!. Thank you for reading!

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