Thermal Engineering

Chapter 6

Flow Through Steam Nozzles

6.1 ❐ INTRODUCTION

The steam nozzle is a passage of varying cross-section by means of which a part of the enthalpy of steam is converted into kinetic energy as the steam expands from a higher pressure to a lower pressure. Therefore, a nozzle is a device designed to increase the velocity of steam. Steam nozzles are of three types, namely convergent nozzle, divergent nozzle, and convergent–divergent nozzle. If the cross-section of the nozzle decreases continuously from the entrance to exit, then it is called a convergent nozzle, as shown in Fig. 6.1(a). If the cross-section increases, then it is called a divergent nozzle, as shown in Fig. 6.1(b). If the cross-section of the nozzle first decreases and then increases, ...