Design a new model of Invelox with a curtain in intake and a vertical outlet

Mohammad Bakir Doctor of Mechanical and Electrical Engineering Faculty

By designing the new model, similar the original model, with the addition of a cylinder-shaped outlet with a diameter of (5.3 m) and a height (4.32 m) which contains inside two guides of air flow up and down to change the direction of airflow up and down. This new model of INVELOX uses double nested cone concept and eight baffles with 360° wind intake capability. This unit is scaled to fit a (1.8 m) diameter wind turbine at the Venturi location. The speed ratio of the velocity at the Venturi V (i) over that of the external free wind V (free), SR=V(i)/V(free), an important design factor. The outlet is cylinder-shaped which contains inside it two guides of airflow up and down.

Figure 2 shows the Physical model of new INVELOX

Figure 3 shows the dimensions of new INVELOX model

2. CFD (computational fluid dynamics) models

The computational domain used in the ANSYS computations had a size of 140 m length, 90 m width and 70 m height. The flow domain was discretized with a mesh of tetrahedral elements. Mesh sizes 9,800,000 elements & 0693011 nodes were used for solution convergence tests in the ANSYS computations, the threedimensional Reynolds-Averaged NaviereStokes (RAN-S) equations were solved numerically with a second-order accuracy upwind schemes and K-omega turbulence model closures with standard wall functions. For the inlet air source, 5% turbulence intensity was used and a length scale of turbulence 1.0 m were used in the computations. Higher mesh resolution was used near the wall regions in the computations.

“Extra Fine” mesh was used in the Venturi duct sections. A constant input velocity field, representing the free stream wind, was assigned to the entire frontal plane of the flow domain. The magnitude of the velocity was set at 6.7 m/s (15 mph).In the simulations, the ground was considered as wall with no-slip conditions. The reference pressure was assumed the atmospheric pressure throughout the domain. Figure. 4 shows mesh distribution on a median cross section of INVELOX.

Figure. 4 mesh distribution on a median cross section of INVELOX

3. Results and Discussion

We study the original and new model of the INVELOX, for seven angles of 0 (0 °, 30°, 60 °, 90 °, 120 °, 150 °, 180 °), so that 0 is the angle confined between the tunnel outlet axis and the direction of free wind. The seven angles covers three sides of the model and considers the rest of the angles similar to the studied angles. For shortcut, we will be display the Velocity contour and streamline airflow in cutaway slice on the plane of symmetry for original and new INVELOX model for three angles (0 °, 90 °, 180 °) and will display the velocity values in Venturi for all angles in Table. 1.

Figure 5 the angle 0 confined between the tunnel outlet axis and the direction of free wind

Figure 6 Velocity contour and streamline airflow in cutaway slice on the plane of symmetry for original INVELOX model. Where (0=°0)

Figure 7 Velocity contour and streamline airflow in cutaway slice on the plane of symmetry for original INVELOX model. Where (0=°O)

Figure 8 Velocity contour and streamline airflow in cutaway slice on the plane of symmetry for original INVELOX model. Where (9=°0)

From the previous figures of the original INVELOX model, shows a lot of the air is passes from the intake to the nozzle and the original INVELOX outlet. The airflow lines inside the original INVELOX model are passed from the intake to the outlet of the tunnel when the angle (0 = 0 °), and the average velocity at the neck is (15.2 m / sec). In addition, when the angle (0 = 90 °), part of the air is passes from the intake to the nozzle and outlet of the tunnel and the other part of air exits from the opposite side of the intake openings. Because of the large turbulence of pressure on both sides of the intake and influence of wind direction in the original INVELOX outlet. The airflow lines inside the original INVELOX model are passes from the intake to the outlet of the tunnel and the mean velocity in the neck is (11.2 m / sec). Moreover, when the angle (0 = 180 °), the total amount of confrontation air for the intake original INVELOX model exits from the opposite side of the intake openings. The speed direction is completely opposite to the direction of the tunnel exit, and the average velocity value is at neck (-8.8 m / sec).

Figure. 9 Velocity contour and streamline airflow in cutaway slice on the plane of symmetry for new INVELOX model. Where (O=°0).

Figure 10 Velocity contour and streamline airflow in cutaway slice on the plane of symmetry for new INVELOX model. Where (0=°O). the plane of symmetry for new INVELOX model. Where (9=°0)

Figure 11 the relationship between velocity values

From the previous figures of the new INVELOX model, shows the total amount of confrontation air for the intake new INVELOX model. The airflow lines inside the new From the previous figures of the new INVELOX model, shows the total amount of confrontation air for the intake new INVELOX model pass inside tunnel .the airflow lines inside the new INVELOX model are passes from the intake to the outlet of the tunnel.

Simulations of airflow for original INVELOX model and new INVELOX model .were performed for angles for seven angles (0 °, 30 °, 60 °, 90 °, 120 °, 150 °, 180 °),so that it covers three sides of the model and considers the rest of the angles similar to the studied angles at inlet air velocity of 6.71 (m/s). The average velocity value in Venturi is given in Table.1

Table 1 shows velocity values at Venturi and velocity values free wind.

Table 2 shows speed ratio for original INVELOX and new INVELOX

Figure 12The effects of wind direction on the speed ratio

Conclusions

The new INVELOX model achieves prevention of reverse flow inside it so that all amount of air passes intercepted by the intake of new INVELOX model passes from the intake to the outlet. In addition, the velocity value in the Venturi region is almost constant and its average value is (16.084 m/sec). The value of SR is almost constant and its average value is 2.39.

References

1. BURTON. T, & JENKINS.N, & SHARPE. D, & BOSSANYI. E, 2011- Wind Energy Handbook. John Wiley & Sons, Second Edition, New York, p741.

2. A Ducted Horizontal Wind Turbine for Efficient Generation I.H. Al-Bahadly and A.F.T. Petersen Massey University New Zealand.

3. Innovatory designs for ducted wind turbines.

4. INVELOX: Description of a new concept in wind power and its performance evaluation.

5. Turbine-intake tower for wind energy conversion systems.

6. Power generating skin structure and power generation system therefor.

7. INVELOX with multiple wind turbine generator systems.

8. Numerical study on the geometrical parameters affecting the aerodynamic performance of Invelox.

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