Normal Shock Wave
A shock wave is a very thin region (of the order of a few molecular mean free paths) across which the
static pressure, temperature, and density increase whereas the velocity decreases. If the shock wave is
perpendicular to the ?ow, it is called a normal shock wave. The ?ow is supersonic ahead of the normal
shock wave and subsonic behind it. Figure 3.7.2 shows the ?ow conditions across a normal shock wave
which is treated as a discontinuity. Since there is no heat added or removed, the ?ow across the shock
wave is adiabatic. By using Equations 3.7.2 the normal shock equations can be written as
One-Dimensional Flow with Heat Addition
Consider one-dimensional ?ow through a control volume as shown in Figure 3.7.3. Flow conditions
going into this control volume are designated by 1 and coming out by 2. A speci?ed amount of heat per
unit mass, q, is added to the control volume. The governing equations relating conditions 1 and 2 can
be written as onedimensional
?ow with heat addition. This curve is called the Rayleigh curve and is drawn for a set of
given initial conditions. Each point on this curve corresponds to a different amount of heat added or
removed. It is seen from this curve that heat addition always drives the Mach numbers toward 1. For a
certain amount of heat addition, the ?ow will become sonic. For this condition, the ?ow is said to be
choked. Any further increase in heat addition is not possible without adjustment in initial conditions.
For example, if more heat is added in region 1, which is initially supersonic, than allowed for attaining
Mach 1 in region 2, then a normal shock will form inside the control volume which will suddenly change
the conditions in region 1 to subsonic. Similarly, in case of an initially subsonic ?ow corresponding to
region 1¢, any heat addition beyond that is needed to attain Mach 1 in region 2, the conditions in region
1¢ will adjust to a lower subsonic Mach number through a series of pressure waves
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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