Quiz 1

The wave is defined by local Mach number that corresponds to three wave

Mach angle

In oblique shock interactions the flow is governed only by the ______ components of the velocity. ______ Component of flow velocity is constant

Normal, Tangential

The _______ consists of infinite number of Mach waves diverging from a sharp corner

Expansion

In aerodynamics the concept of ____ is not used because it's not a relevant or useful parameter for compressible airflow around airfoils. Instead it is treated as a bulk property that varies with altitude and temperature

Total Density

As the upstream Mach number increases ______

Wave angle decreases

Tuck under occurs when ______

The aircraft reaches Mcr

Air passes through a compression wave. Which of the following statements is correct?

The pressure increases

First-Order Approximation is the well-known linear theory to the incremental pressure change through an oblique shock wave created by deflecting a supersonic stream of unit Mach number M through a small angle θ

Ackeret

______ drag may be represented as the sum of the contributions developed by four basic types: skin friction form (or pressure) induced wave

Profile

Drag increases with flow and lift decreases but greater than the lift increase resulting in symmetrical airfoils. Which shape will give the highest possible lift-drag ratio?

Bi-convex airfoil

The ____ may be considered to be the minimum practical airfoil cross-sectional shape to give the least drag per unit span

Flat Airfoil

A _____ surface formed by segments of straight lines

Parabol

A ____ has its sections at an aft end normal to the surface face of the base and therefore it forms a corner when attached to a cylinder

Conical ogive

____ nose cones are employed when rocket motors are used for propulsion

Conical

Applied to that force which results from the negative pressure on the aft near portion of an airfoil

Profile drag

This shockwave is unattached to the surface and is ahead of the leading edge

Bow Shock / Detached Shock

If the Mach number upstream of the normal shock is greater than 1 Mach number downstream is

Always less than 1

Across the shockwave the static temperature ______ while the total temperature _________

Increases, constant

The Mach number downstream of a normal shock wave is

Always subsonic

Normal shockwaves are _______

adiabatic

In a subsonic flowthe total pressure that is being measured by a pitot tube is ___________

Freestream total pressure

In a supersonic flow the total pressure that is being measured by a pitot tube is _______

Total pressure behind the shock wave

As air flows through a shock wave

Static pressure increases, density increases, temperature increases

At speeds above the critical Mach number the lift coefficient

Will start to decrease

The airflow behind a normal shock wave will

Always be subsonic and in the same direction as the original airflow

As the upstream Mach number increases _______

wave angle decreases

As the deflection angle increases _______

wave angle increases

Oblique and Expansion shockwaves are _______

Two dimensional

Normal shockwaves are _______

One dimensional

Wave that is said to be an infinite collection of Mach waves _______

Expansion

Changes across an oblique shock wave are governed only by the component of velocity _______ to the wave

normal

Why is the energy conversion that takes place at the upstream stagnation point?

Kinetic energy to pressure energy

Which statement is correct about an expansion wave in a supersonic flow? i. The upstream temperature of an expansion wave is higher than the downstream temperature. ii. The upstream Mach number of an expansion wave is lower than the downstream Mach number

Statement 1 and statement 2 are correct

Tuck under occurs when ___________

The aircraft reaches Mcrit

The angle which the Mach line makes with the free stream direction and it is defined by the relative velocities between the free stream velocity and the speed of sound in the stream

Mach angle

Air passes through a compression wave. Which of the following statements is correct?

The pressure increases