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Correct option is (a) True

The best I can explain: The Kutta-Joukowski theorem is a fundamental theorem of AERODYNAMICS, this can be used for calculating of lift of an airfoil, or of any two-dimensional bodies including CIRCULAR cylinders TRANSLATING in a uniform fluid at a constant speed large ENOUGH so, that the flow seen in the body is fixed FRAME is steady and unseparated.

Right choice is (c) Γ=-2*pi*C

The explanation: The circulation for vortex flow can be GIVEN by –

Γ=2*pi*C where, C – CONSTANT and Γ is the strength of the vortex flow.

When Γ is positive, it means that vortex of positive strength rotates in the clockwise direction and vice VERSA.

Right CHOICE is (b) no slip CONDITION

The explanation is: At the boundary of solids, the velocity at a POINT becomes zero. Dirichlet’s condition is an example of no slip-condition. When the adhesive forces are stronger than cohesive force the particle does not move and HENCE no slip-condition OCCURS.

Correct choice is (a) 0

To explain I would say: In IRROTATIONAL flow, the fluid FLOWS in linear DIRECTION only and if the stream function exits the flow may be either rotational or irrotational. When the stream function satisfies the Laplace equation, it the case of irrotational flow.

Correct option is (a) INTERSECT each other

To explain: Two pathlines can intersect each other because the same PARTICLE or the different particle MAY come again at the same place at different time. Moreover, pathline is just a path followed by the fluid particle. Two or more fluid PARTICLES can FOLLOW the same path.

The correct ANSWER is (b) same

Explanation: A pathline is a path followed by a FLUID flow particle. Whereas, streamline is a point in the fluid flow at which if a tangent is drawn, it gives the direction of the fluid flow. But in a steady flow, the velocity REMAINS constant throughout the flow, hence the pathline and streamline become the same.

Correct answer is (c) SOURCE flow

Easiest explanation: In a source flow, the flow velocity is DIRECTED AWAY from the origin. All the STREAMLINES are the straight lines and they vary inversely with DISTANCE which means as the distance increases the velocity decreases.

Correct answer is (d) stream-tubes

Easiest explanation: A GROUP of streamlines forming a passage through which the FLOW passes is CALLED as stream-tubes. They are bounded by a number of streamlines. The fluid may enter or LEAVE the SURFACE through the ends of the stream-tubes.

The correct answer is (a) Lower part

The best I can EXPLAIN: The stagnation point moves to the lower part of the cylinder, similar to the theoretical flow. If the spin is SUFFICIENTLY increased the stagnation point lifts off the surface. Position of stagnation point is a STRONG FUNCTION of circulation, with zero circulation stagnation point lies at zero.

Right answer is (b) closed body profile

The best I can explain: The shape of the Rankine oval of EQUAL AXES can be given by substituting the STREAM function as zero in the equation Ψ = U*y + ((-u/2*pi*r)*sin θ. When U*y+ ((-u/2*pi*r) =0, a closed profile body is a circular cylinder of radius R with the CENTRE on the doublet.

Correct choice is (a) flow net

To EXPLAIN I WOULD say: The grid OBTAINED by drawing a series of equipotential lines and stream lines is called a flow net. A flow net is an important tool in analyzing two-dimensional flow problems.

Correct choice is (b) steady non-uniform FLOW

Explanation: The flow in a tapering PIPE has variable GEOMETRY. The cross section of the tapered pipe is not uniform but the rate of fluid flow is constant THROUGHOUT the flow. Any duct which has non-uniform cross section but the hydrostatic PARAMETERS remain constant fall under this category.

The correct choice is (b) True

To EXPLAIN I WOULD say: The strength of an infinitesimal portion of the SHEET. This is small section of the source sheet can be treated as a distinct source of strength. The flow is LOCATED at a DISTANCE from dx. The carterian coordinates of ‘P’ are (x, y). This is the small section of the source sheet of strength xds induces an infinitesimally small potential.

The correct OPTION is (d) LOWER and upper surface

The best I can EXPLAIN: Fluid moving along the lower and upper surface of the airfoil should meet at the sharp TRAILING edge. Since viscous dissipation PREVENTS the fluid to turn around the sharp edge. This is known as the Kutta-Condition for real flow.

Right OPTION is (a) LIFT per unit span on the airfoil

The explanation: The Kutta-Joukowski theorem states that lift per unit span on a Two-Dimensional body, is DIRECTLY propositional to the CIRCULATION around the body. It is a fundamental theorem of aerodynamics used for the CALCULATION of the lift of an airfoil and any two-dimensional body.

The correct answer is (a) True

The explanation is: The numerical SOLUTION of potential FLOWS by both SOURCE and vortex panel techniques has revolutionized the analysis of low-speed flows. The purpose of the numerical solution is to introduce the BASIC ideas of the source panel METHOD, which is a technique for the numerical solution of non-lifting flows over arbitrary body.

Correct choice is (a) DUE to viscous effect

The explanation: Drag is due to a viscous effect, which generate a frictional shear stress at the body surface and which CAUSES the flow to separate from the surface on the BACK of the body. At the leading edge of the cylinder, a stagnation point is formed. Where the oncoming flow is brought to rest. The pressure here is EQUAL to the stagnation pressure. At the adjacent to the cylinder surface, a thin boundary layer is formed. Which causes the drag on the cylinder.

Correct option is (b) CONCENTRIC circles

Easy explanation: The free VORTEX flow is a circulatory flow of the fluid such that its stream lines are concentric circles. The velocity COMPONENTS for a free vortex flow are Ur and Uθ and is equal to Ur=0 and Uθ=circulation/ 2*PI*R.

The correct option is (d) free vortex flow

Explanation: The above figure SHOWS the concentric circles ALONG with STREAMLINES. Here, the STREAM function is a function of radius and it is constant VALUE and hence the streamlines are concentric.

Correct choice is (a) Pressure and lift

The EXPLANATION: Kutta and Joukowski discovered that for computing, the pressure and lift of a thin enough airfoil for flow with large enough REYNOLDS number and at small enough angle of attach the flow can be assumed INVISCID in the entire REGION provided the Kutta condition is IMPOSED.

The CORRECT answer is (a) 0

The best explanation: In the source flow, the VELOCITY COMPONENT is only in the RADIAL direction (Vr). The tangential component of the velocity (VT) is zero.

Correct answer is (b) Large number of unsteady flow

For explanation I would say: When there are free vortices outside of the body as MAY be the CASE for a large number of unsteady flow, the flow is rotational. A fluid is said to be rotational if fluid particles are rotating about their own mass CENTER, otherwise, flow is irrotational.

Correct choice is (a) True

To explain: The pressure imbalance creates a net upward force that is a finite lift. Therefore flow over a circular CYLINDER can produce a finite lift, from Bernoulli’s equation that as the VELOCITY INCREASES, and the pressure decreases and hence the pressure on the top of the cylinder is LOWER than on the bottom. This pressure imbalance will create a net upward force, i.e. a finite lift.

Right option is (d) Due to fluctuations in the flow

The explanation: The difference in PRESSURE is caused by the PERIODIC separation of flow over the surface of the CYLINDER. Periodic separation induces fluctuations in the flow and makes cylinder VIBRATE in the wind TUNNEL.

Correct answer is (a) Ψ=0

Easiest explanation: The shape of the Rankine oval of equal axes can be given by substituting the stream function as ZERO in the equation Ψ = U*y + ((-u/2*pi*r)*sin θ. This GIVES US two DIFFERENT solutions for which the shape of oval varies.

The correct answer is (a) P = PFREESTREAM + q

To explain: For Cp=1, the flow BECOMES INCOMPRESSIBLE and in general Cp TELLS us how much p differs from Pfreestream in multiples of the dynamic pressure. When Cp=1, it tells that local pressure is one times the dynamic pressure above freestream STATIC pressure.

Correct option is (b) non-uniform flow

Explanation: The flow in which all the hydrostatic PARAMETERS CHANGE from one point to other is called non-uniform flow. The changes may be in DIRECTION of flow or in the direction perpendicular to the flow. The example of the changes perpendicular to the flow is the flow over the SOLID bodies.

The CORRECT answer is (a) true

The EXPLANATION is: All the HYDROSTATIC parameters change from time to time in unsteady flow including the velocity. The streamline DEFINES the direction of flow when a tangent is drawn from any point in that flow field. As the velocity changes, the STREAMLINES to changes.

The correct choice is (a) True

Easiest explanation: The dynamic pressure can be used in all kinds of FLOW. It is denoted by ‘q’ and is the GROUPING of DENSITY and VELOCITY in which the density is halfed and the velocity is squared.

q=0.5*ρ*V^2.

Right option is (c) 90 degrees

To elaborate: The lower end of the tube is BENT at an ANGLE of 90 degrees. The liquid rises up in the tube due to the conversion of kinetic energy into the pressure energy. The velocity is determined by MEASURING the RISE of the liquid in the tube.

Right option is (c) HIGHER mach numbers

For EXPLANATION: Bernoulli’s principle states that increasing the velocity DECREASES the PRESSURE which gives us a higher lift. If the matches the number increases, gradually the pressure decreases which leads to an increase in lift.

Correct CHOICE is (b) stagnation POINT

Explanation: At stagnation point, the value of velocity is 1 and therefore Cp = 1 – (V2/ V1)^2

GIVES the value of the coefficient of pressure as 1. This is true only for INCOMPRESSIBLE flow. Stagnation point gives the highest value of the coefficient of pressure.

The correct OPTION is (d) throat

To explain: When the flow enters the wind tunnel (convergent-divergent) with a VELOCITY V1 and pressure P1. The velocity increases and the pressure decreases at the MINIMUM area SECTION called the throat. Pressure is minimum at the throat.

The correct ANSWER is (a) drag polar

For explanation I would SAY: It is CALLED drag polar and it gives the relation between the lift and drag of the aircraft. It describes the amount of lift generated per drag PRODUCED. Cl/Cd ratio must be HIGH. The amount of lift generated should be more with relatively less drag.

Right CHOICE is (a) True

To EXPLAIN: An increase in speed of the flow leads to an increase in kinetic energy and DYNAMIC pressure (0.5ρ*V^2). As the dynamic pressure increases that is the density is halved and the velocity is squared, the static pressure DECREASES along with the DECREASE in potential energy and internal energy.

Correct answer is (c) Quasi 1D flow

The explanation: GENERALLY, the flow field properties are UNIFORM across any cross section and hence, they vary only in x-DIRECTION. All the flow parameters are assumed to be the function of x. A=A(x), V=V(x), p=p(x) and SINCE they vary only in one direction they are called quasi 1D flow.

Correct option is (a) directly PROPORTIONAL to each other

To explain: Gay-Lussac’s law states the relationship between temperature and PRESSURE. They are directly proportional to each other. Increase in temperature increases the pressure and VICE versa. When the temperature increases, the gas MOLECULES move FASTER and hence the pressure increases.

Correct answer is (d) ABSOLUTE pressure

The best I can explain: Absolute pressure is MEASURED with respect to vacuum. A vacuum has an absolute pressure of 0 PSI. It is also DEFINED as the sum of gauge pressure and atmospheric pressure.

The correct ANSWER is (b) -1

The best explanation: GENERALLY the gliders have the pressure coefficient of -1 because it indicates the location of total ENERGY and this total energy is USED by variometer (a vertical speed indicator)which reacts to all the vertical movements of the atmosphere.

Correct answer is (b) False

Best explanation: Pitot tubes with FLAT faces are LEAST SENSITIVE. For these tubes, the total pressure measurement varies only 1 percent for misalignment as large as 20 degrees.

The correct choice is (b) Low speed wind TUNNEL

The explanation is: Low speed wind tunnel is a LARGE venturi where the airfoil is driven by a fan connected to some TYPE of motor drive. The wind tunnel fan is similar to the propeller of an aircraft and is designed to DRAW the airflow through the tunnel CIRCUIT.

The correct choice is (a) VENTURI DUCT

Explanation: In venturi duct, the pressure at the throat(P2) is lower than the pressure at the inlet(P1). The pressure DIFFERENCE p2-p1 helps to force the fuel into the airstream and mix it with the airstream downstream of the throat.

The correct answer is (a) temperature

For EXPLANATION: Using venturi, velocity can be measured. We can calculate the PRESSURE DIFFERENCE using venturi. In the duct, we can place pressure GAUGE which will directly give us the pressure difference (p2-p1). This pressure difference can be RELATED to velocity using Bernoulli’s equation and hence, the velocity can be calculated.