tailieunhanh - Ebook Fundamentals of compressible fluid mechanics: Part 2

(BQ) Part 2 book "Fundamentals of compressible fluid mechanics" has contents: Normal shockin variable duct areas, nozzle flow with external forces, isothermal flow, fanno flow, evacuating and fillinga semi rigid chambers, rayleigh flow,. And other contents. | CHAPTER 6 Normal Shock in Variable Duct Areas In the previous two chapters, the flow in a variable area duct and a normal shock (discontinuity) were discussed. A discussion of the occurrences of shock in flow in a variable is presented. As it is was presented before, the shock can occur only in steady state when there is a supersonic flow. but also in steady state cases when there is no supersonic flow (in stationary coordinates). As it was shown in Chapter 5, the gas has to pass through a converging–diverging nozzle to obtain a supersonic flow. In the previous chapter, the flow in a convergent– divergent nuzzle was presented when the pressure ratio was above or below the special range. This Chapter will present the flow in this special range of pressure ratios. It is c interesting to note that a normal a Subsonic shock must occur in these situations (pressure ratios). d In Figure () the reSupersonic duced pressure distribution in b the converging–diverging nozdistance, x zle is shown in its whole range of pressure ratios. When the Fig. : The flow in the nozzle with different back prespressure ratio, P B is between sures 0& ( ' ©§)%& $ %# # 7 6 ¡35 w ic flo subson shock a 4 2 ¡31 123 after 124 CHAPTER 6. NORMAL SHOCK IN VARIABLE DUCT AREAS point “a” and point “b” the flow is different from what was discussed before. In this case, no continuous pressure possibly can exists. Only in one point where P B = Pb continuous pressure exist. If the back pressure, P B is smaller than Pb a discontinuous point (a shock) will occur. In conclusion, once the flow becomes supersonic, only exact geometry can achieve continuous pressure flow. In the literature, some refer to a nozzle with an area ratio such point b as above the back pressure and it is referred to as an under–expanded nozzle. In the under–expanded case, the nozzle doesn’t provide the maximum thrust possible. On the other hand, when the nozzle exit area is too large a shock will occur and other phenomenon such as

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• Fundamentals of compressible fluid mechanics
• Compressible fluid mechanic
• Normal shockin variable duct areas
• Nozzle flow with external forces
• Isothermal flow
• Fanno flow
• Evacuating and fillinga semi rigid chambers
• Basic fluid mechanics
• Speed of sound
• Isentropic flow
• Normal shock
• Fundamentals of fluid mechanics
• Fluid mechanics
• Viscous flow in pipes
• Flow over immersed bodies
• Open channel flow
• Compressible flow
• Ebook Fluid mechanics
• Momentum analysis of flow systems
• Dimensional analysis
• Flow in pipes
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