Question

Both qualitatively and quantitatively understand how the properties of a flow change through a normal shock. Know why a normal shock is called a normal shock. Know what object shapes cause normal shocks to form, and what object shapes cause attached oblique shocks to form. Know where to find a normal shock or normal shocks on an airplane or rocket for any Mach number ldentify shocks in photographs, and characterize important parts of the flow (supersonic vs subsonic, etc) Qualitatively compare the Mach number of different flows from photographs. Understand the difference between static property values and total property values. Qualitatively compare static and total values of pressure, temperature, and density for different points of a flow before and after a bow shock. Understand the difference between Mach waves and normal shocks. Properties you should be able to calculate: P, Po, P. T, TO, T*, ρ, ρο, ρ*, M, v, a, ao, a*, M* Calculate properties for flows that are ISENTROPICALLY accelerated or decelerated. Calculate any of the flow properties before or after a normal shock using equations or property tables. Calculate properties for flows other than air Calculate force from pressure and area.

Answer 1

When there is a shock in a flow, the physical properties of the flow change very abruptly over a very small distance
Across a shock wave, the static pressure, temperature, and gas density increases almost instantaneously. Because a shock wave does no work, and there is no heat addition, the total enthalpy and the total temperature are constant. But because the flow is non-isentropic, the total pressure downstream of the shock is always less than the total pressure upstream of the shock. There is a loss of total pressure associated with a shock wave. The ratio of the total pressure is shown on the slide. Because total pressure changes across the shock, we can not use the usual (incompressible) form of Bernoulli's equation across the shock. The Mach number and speed of the flow also decrease across a shock wave.

A normal shock is called a normal shock because in this case the shockwave is normal to the flow direction and hence the name normal shock

normal shock are formed by large buff objects near their surfaces like pipe entry, walls etc where as attached oblique shocks are formed by more streamlined bodies allowing flow to move aside as well like airplane fuselage nose etc

in a shock, if the region behind the shock is subsonic than the region ahead of the shock is supersonic and vice versa
stron shocks ar emore close to normal shocks in shapes than oblique shocks and hence oblique shocks are weaker
the following image outlines important parts of a shock

When there is a shock in a flow, the physical properties of the flow change very abruptly over a very small distance Across a shock wave, the static pressure, temperature, and gas density increases almost instantaneously. Because a shock wave does no work, and there is no heat addition, the total enthalpy and the total temperature are constant. But because the flow is non-isentropic, the total pressure downstream of the shock is always less than the total pressure upstream of the shock. There is a loss of total pressure associated with a shock wave. The ratio of the total pressure is shown on the slide. Because total pressure changes across the shock, we can not use the usual (incompressible) form of Bernoulli's equation across the shock. The Mach number and speed of the flow also decrease across a shock wave. A normal shock is called a normal shock because in this case the shockwave is normal to the flow direction and hence the name normal shock