aero midterm

Question 1

Temperature is a measure of the average ______ energy of the particles in a gas

Answer 1

kinetic

Question 2

A perfect gas is one in which intermolecular forces are negligible.

Answer 2

True

Question 3

the equation of state for a perfect gas is given by…

Answer 3

p = rhoRT

Question 4

What are the sources of aerodynamic forces acting on a body

Answer 4

pressure distribution and shear stress distribution over the surface

Question 5

In isothermal regions of the standard atmosphere, temperature s said to change as altitude changes

Answer 5

False

Question 6

in both the gradient and isothermal regions of the standard atmosphere, the pressure ____ with an increase in altitude

Answer 6

decreases

Question 7

The continuity equation for steady fluid flow states that

Answer 7

rho1A1V1 = rho2A2V2

Question 8

For incompressible flow

Answer 8

rho1 = rho2

Question 9

You are given a convergent duct for which the inlet area A1 is greater than the outlet area A3. Assuming that flow in this duct is incompressible, the velocity of the flow will _____ as it moves through the duct.

Answer 9

increase

Question 10

An inviscid flow is one that is frictionless

Answer 10

true

Question 11

An isentropic process is one that is both adiabatic and reversible. Thus, an isentropic process is one in which there is _____ .

Answer 11

neither heat exchange nor any effects due to friction

Question 12

the speed of sound in a perfect gas depends only on the temperature of the gas.

Answer 12

true

Question 13

Mach number is the ratio of the flow velocity to the speed of sound. If a flow has M = 1, the flow is said to be ____ .

Answer 13

sonic

Question 14

Consider a subsonic wind tunnel with a typical upstream-to-downstream arrangement consisting of a reservoir, nozzle, test section, and diffuser. In such a wind tunnel, the test section pressure is ______ than the reservoir pressure.

Answer 14

smaller than

Question 15

In a subsonic wind tunnel, a manometer is used to measure the _____ difference between the nozzle and test section.

Answer 15

pressure

Question 16

The ____ at a given point in a flow is the pressure that would exist if the flow were slowed down isentropically to zero velocity.

Answer 16

total pressure

Question 17

A pressure gauge connected to a pitot static probe measures the difference between the ____.

Answer 17

total and static pressure

Question 18

Flow speeds below M = 0.3 are

Answer 18

incompressible

Question 19

Flow speeds above M = 0.3 are

Answer 19

compressible

Question 20

shock waves are very thin regions of the flow across which some severe changes in the flow properties take place. Assuming that the perfect gas assumption exists, as a fluid element flows through a shock wave, the total temperature T0 _____.

Answer 20

stays the same

Question 21

Consider an airplane flying at some true airspeed at some altitude. It’s equivalent airspeed at this condition is defined as the velocity at which it would have to fly at standard sea level to experience the dame dynamic pressure.

Answer 21

True

Question 22

The area velocity relation states that, for supersonic flows (M>1), the cross sectional area must _____ for the velocity to increase.

Answer 22

increase

Question 23

Flow speeds below Mach 0.3 are typically treated as incompressible because the ____ is essentially constant at these speeds.

Answer 23

density

Question 24

flow that consits of friction is known as _____ flow

Answer 24

viscous

Question 25

flow that consists of friction is known as _____ flow

Answer 25

viscous

Question 26

The flow in a boundary layer consists of a velocity profile which exhibits a change in flow velocity between the object’s surface and the outer edge of the boundary layer. Let the velocity at the surface be given by V1 and the velocity at the outer edge of the boundary layer be given by V2. Which of the following describes the velocity profile in the boundary layer?

Answer 26

V1 < V2

Question 27

Consider viscous flow over a flat plate. As the air flows across the surface from the leading edge to the trailing edge (ie. front to back), one would expect the thickness of the boundary layer to _______.

Answer 27

increase

Question 28

Laminar flow is one in which the streamlines break up and a fluid element moves in a random, irregular, and tortuous fashion.

Answer 28

False

Question 29

Consider viscous flow over a surface. The flow in the boundary layer may be categorized as laminar or turbulent. The presence of fiction creates a shear stress at the surface tau-w . Let tau-w-laminar represent this shear stress in the case of laminar flow and tau-w-turbulent represent this shear stress in the case of turbulent flow. Which of the following is accurate?

Answer 29

tau-w-laminar < tau-w-turbulent

Question 30

Under the same flow conditions, a turbulent boundary layer will be thicker than a laminar boundary layer.

Answer 30

True

Question 31

Consider a flat plate boundary layer in a compressible flow. In such a case, for a constant Reynolds number, the effect of increasing the freestream Mach number M_inf is to _______ the local skin friction coefficient c_f_x.

Answer 31

decrease

Question 32

The major consequences of flow separation over an airfoil are _______ .

Answer 32

a large decrease in lift and a large increase in drag

Question 33

In the presence of an adverse pressure gradient, fluid elements along a streamline within the boundary layer tend to _______ .

Answer 33

slow down

Question 34

Skin friction drag is caused by flow separation at the surface of the object.

Answer 34

False

Question 35

Pressure drag due to separation can be reduced by establishing a turbulent boundary layer on the surface.

Answer 35

True

Question 36

The lift of an airfoil L is always defined as the component of the aerodynamic force _______ to the _______.

Answer 36

perpendicular/ relative wind

Question 37

The normal and axial forces of an airfoil may be related to the lift and drag of the airfoil through the angle of attack.

Answer 37

True

Question 38

The moment coefficient c_m is obtained by dividing the moment M by which of the following?

Answer 38

q_inf*S*c

Question 39

The lift slope is given by the slope of the linear portion of a plot of:

Answer 39

cl vs alpha

Question 40

A positively cambered airfoil will have a non-zero value of cl at zero angle of attack.

Answer 40

true

Question 41

At some angle of attack larger than that corresponding to cl_max , the flow around an airfoil typically remains attached.

Answer 41

False

Question 42

At high subsonic Mach numbers in a flow, the associated compressibility effects have no influence on the low-speed pressure coefficient.

Answer 42

False

Question 43

Consider a flat plate at a positive angle of attack in a flow field with freestream velocity of M_inf > 1. At the leading edge on the upper surface of this flat plate, one would observe a/an _______ .

Answer 43

expansion wave

Question 44

At subsonic speeds below the drag-divergence Mach number, one would expect to have a significant amount of wave drag.

Answer 44

false

Question 45

For values of Mach number between M = M_dragdivergence and M = 1 , one would expect _______ in the drag coefficient cd.

Answer 45

an increase

Question 46

The only two sources of Aerodynamic forces on a body are

Answer 46

Pressure and Shear Stress

Question 47

Total Pressure is the pressure you would feel if you were traveling along with a fluid element in a flow

Answer 47

False

Question 48

Static Pressure is the pressure you would feel if you were traveling along with a fluid element in a flow

Answer 48

True

Question 49

Compressible flows that are isentropic (adiabatic and reversible) have constant static temperatures throughout the flow since both heat addition and friction are ignored

Answer 49

False

Question 50

As altitude increases in the troposphere below the tropopause, the speed of sound

Answer 50

decreases

Question 51

At sea level, the true and equivalent velocities are equal

Answer 51

True

Question 52

Assuming compressible, steady, isentropic flow, and a constant mass flow rate, if the flow entering a duct is supersonic, to decrease its velocity, you must ____ the area along the direction of the flow.

Answer 52

decrease

Question 53

when you have achieved choked flow in the throat of a nozzle you can continue to increase the mass flow rate by continuing to decrease the pressure at the exit of the nozzle.

Answer 53

False

Question 54

The equation of state for an ideal gas states the relationship between pressure, temperature, and density of an ideal gas at different points in the same flow

Answer 54

false

Question 55

The assumptions used to derive both Bernoulli's Equation and the energy equation result in both total pressure and total temperature being constant along a streamline.

Answer 55

True

Question 56

Aerodynamics is defined as the science that deals with the transfer of energy

Answer 56

False

Question 57

Pressure is a scalar quantity and can be defined in cartesian space by one component

Answer 57

True

Question 58

velocity is just another word for speed; there is no technical difference between them.

Answer 58

False

Question 59

The static pressure at a given point is the pressure we would feel if the flow were brought isentropically to rest at that point.

Answer 59

False

Question 60

The conservation of momentum is another form of Newton's Second Law of motion

Answer 60

True

Question 61

The velocity always increases in a convergent nozzle

Answer 61

False

Question 62

Because there is no heat transfer in an isentropic process, the temperature of the flow must remain constant everywhere in the flow.

Answer 62

False

Question 63

The total pressure and total temperature remain constant across a shock wave.

Answer 63

False (total pressure decreases)