POF MOCK 7-10-19

Considering subsonic incompressible airflow through a Venturi, which statements are correct or incorrect?

1) The dynamic pressure in the undisturbed airflow is the same as in the throat.

2) The total pressure in the undisturbed airflow is higher than in the throat.

• 1) is correct, 2) is correct.

• 1) is incorrect, 2) is correct.

• 1) is correct, 2) is incorrect.

• 1) is incorrect, 2) is incorrect.

Considering subsonic incompressible airflow through a Venturi, which statements are correct or incorrect?

1) The dynamic pressure in the undisturbed airflow is lower than in the throat.

2) The total pressure in the undisturbed airflow and in the throat is the same.

• 1) is correct, 2) is incorrect.

• 1) is incorrect, 2) is incorrect.

• 1) is incorrect, 2) is correct.

• 1) is correct, 2) is correct.

Which of the following statements about drag and lift is correct?

• Drag is acting in the direction of the chord line and lift is perpendicular to the chord line.

• Drag is acting in the direction of relative wind (airflow) and lift is perpendicular to the relative wind (airflow).

• Drag is acting in the direction of horizon and lift is perpendicular to the horizon.

• Drag is acting in the direction of longitudinal axis and lift is perpendicular to the longitudinal axis.

Bernoulli's equation can be written as (P_T = total pressure, P_S = static pressure, q = dynamic pressure):

• P_T = P_S - q

• P_T - q = P_S

• P_T + P_S = q

• P_T = q - P_S

Assuming no flow separation, which of these statements about the flow around an aerofoil as the angle of attack decreases are correct or incorrect?

1) The stagnation point moves up.

2) The point of lowest static pressure moves forward.

• 1) is correct, 2) is incorrect.

• 1) is correct, 2) is correct.

• 1) is incorrect, 2) is correct.

• 1) is incorrect, 2) is incorrect.

Which statement is correct?

• The centre of pressure is the point on the aerofoil leading edge where the airflow splits up.

• As the angle of attack increases, the stagnation point on the aerofoil's profile moves downwards on the profiles leading edge.

• The stagnation point is another name for centre of pressure.

• The stagnation point is always situated on the chord line, the centre of pressure is not.

Which of these statements about the strength of wing tip vortices are correct or incorrect?

1) Assuming no flow separation, the strength of wing tip vortices is not affected by the angle of attack.

2) The strength of wing tip vortices decreases as the aspect ratio increases.

• 1) is incorrect, 2) is incorrect.

• 1) is correct, 2) is correct.

• 1) is correct, 2) is incorrect.

• 1) is incorrect, 2) is correct.

Which statement concerning the local flow pattern around a wing is correct?

• Slat extension, at a constant angle of attack and normal extension speeds, will increase the lift coefficient, which will also increase the induced drag coefficient.

• By fitting winglets to the wing tip, the strength of the wing tip vortices is reduced which in turn reduces induced drag.

• Sweepback reduces drag since, compared with a straight wing of equal area, the span increases.

• Vortex generators on the wing partially block the spanwise flow over the wing leading to a reduction in induced drag.

Which of these statements about the strength of wing tip vortices are correct or incorrect?

1) Assuming no flow separation, the strength of wing tip vortices increases as the angle of attack increases.

2) The strength of wing tip vortices decreases as the aspect ratio increases.

• 1) is incorrect, 2) is incorrect.

• 1) is incorrect, 2) is correct.

• 1) is correct, 2) is correct.

• 1) is correct, 2) is incorrect.

Which of these statements about induced drag are correct or incorrect?

1) A rectangular spanwise lift distribution generates more induced drag than an elliptical lift distribution.

2) Induced drag decreases with increasing aspect ratio.

• 1) is incorrect, 2) is correct.

• 1) is incorrect, 2) is incorrect.

• 1) is correct, 2) is correct.

• 1) is correct, 2) is incorrect.