Aerodynamics Exam Flashcards
Why are there different kinds of aerodynamic effects (pressure, force, moment, etc.) ?
As wind effects are dependent on time an d space on the surface
Based on which theortical assumption are streamlimes used for the pressure analysis?
Bernoulli equation and continuity equation, assuming a steady flow
Which wind parameters are influence by the terrain roughness surrounding in a specific location?
a) Turbulence intensity
b) Average velocity
c) Return periode
d) Integral length scale
A)
B)
D)
Why is the underlying averaging time for wind velocity an important information?
A) The maximum values depent on the averaging time
B) With increasing time, the wind velocity increases too
C) For the structual calculation normally values with an averging time of 2-3s are needed
D) Dependent on the building size, an appropriate averaging time needs to be selected
A)
C)
What is true for the integral length scale Lux?
A) Describes the average diameter of a gust vortex
B) Describes a flow relation between time and space
C) Is a measure of flow the correlation in space
A)
B)
C)
What is the adventage of aerodynamic coefficients?
A) They are valid for each kind of geometry
B) They are valid independent on wind zone and roughness category
C) For most objects they are not dependent on scale
B)
C)
What is the right formula to determine a force coefficient based on a force F measured in the wind tunnel?
A) cf = qm/F
B) cf = F/(qm*A)
C) cf = F*qm/ A
B)
Based on which hydrodynamic relations can the pressure coefficients be derived?
A) Strouhal and Reynolds relation
B) Stagnation and geometry relation
C) Bernoulli and Continuity relation
C)
How can cpe1 and cpe10 values be measured/analyzed based on experimental investigation ?
A) Using time filtering
B) Using many pressure taps in a small area
C) Using sensors with different precision
A)
B)
In which situation is an effect-related force coefficient more favorable compared to a set of pressure coefficients?
A) Overall design of building cladding system
B) Total force for the foundation design
C) Permeable structures like lattice structure
B)
C)
What is a know disadventage of the pressure coefficients for vertical walls and roofs provided in Eurocode?
A) They do not consider the correlation effect
B) They are simplified with respect to the wind direction
C) They are overasfe for highrise structures
B)
How can cpe1 and cpe10 values be measured/analyzed based on experimenatl investigations?
a) Using time filtering
b) Using many pressure
c) Using sensors with different precision
a)
b)
What is different with respect to sharpe-edged / rounded objects in aerodynamics?
a) Forces are limited / unlimited
b) Pressure separation points are fixed/ variable
c) Lateral forces are asymmetric / symmetric
b)
