Phenomenon in Nozzles Operating Off the Design Pressure Ratio: Consider a convergent nozzle as shown in Fig. 4. Figure 19.5 shows the actual expansion of steam through nozzle. A convergent divergent adiabatic steam nozzle is supplied with steam at 10 bar and 250°c.the discharge pressure is 1.2 bar.assuming that the nozzle … A duct which decreases the velocity of a fluid and causes a corresponding increase in pressure is a. In the nozzle, the velocity of the fluid is so high that there is hardly any time available for fluid to exchange heat with the surroundings. Most of the friction in convergent-divergent nozzle is assumed to occur between the throat and exit. Introduction to Slotting Machine : The actual heat drop (h1 – h3) is known as a useful heat drop. The result of thermal analysis shows that thermal loads have a great effect in generating a huge amount of stresses on the nozzle structure (more than 60% from the total stresses on the nozzle). (i) When pressure P2 is equal to Pt, there is no decrease in pressure and therefore mass-flow rate is zero. 2. It is a point, where the saturation line meets the initial pressure (P1) line. The density of supersaturated steam is greater than the equilibrium density at the same pressure. Situation second: When back pressure is less than the critical pressure divergent nozzle is used. Let us see the nozzle which is fitted at … Turbo machines like steam turbines, water turbines and gas turbines produce power by utilising the kinetic energy of the jets produced by passing high pressure steam, water and gas through the devices called nozzles. The steam in states between S and B is supersaturated or a metastable state. (ii) When pressure P2 is less than P1, but more than critical pressure; distribution along the axis is shown by curve (II). Now the actual expansion of steam in the nozzle is expressed by the curve AB’ (adiabatic expansion) instead of AB (isentropic expansion). 3. Divergent nozzle: Cross-sectional area is increases continuously from entrance to exit. But by using convergent nozzle we cannot obtain super-sonic flow. As the expansion of steam ends at the pressure P2, therefore a final condition of steam is obtained by drawing a horizontal line through C to meet the final pressure (P2) Line at B’. Therefore, a nozzle is a device designed to increase the velocity of steam. if the fluid is steam, then the nozzle is called as Steam nozzle. The flow of steam through nozzles may be taken as adiabatic expansion. If the area of the exit section of a nozzle is such that the fluid expands to a pressure at this section less than that of the discharge region. The achievement of equilibrium between the liquid and vapour phase is therefore delayed and vapour continues to expand in a superheated or dry state. The efficiency of a nozzle generally varies from 0.85 to 0.95. UNIT I STEAM NOZZLE 9. If Mach number is equal to one, flow is sonic. Nozzles are used for flow measurement e.g. There are three main types of welding nozzles: hand, speed, and tacking (Fig. If What you looking for is not here, you may send a request to modify articles, Notes, and Content modification, Feedback, Suggestions here (Team will reply as early as Possible ):  Contact Form or Using Whatsapp, © 2021 Copyright Learn Mechanical Engineering, What is Steam Nozzle | Types Of Steam Nozzle shapes. Thank you For Visiting. 3. In case (IV), pressure is critical at throat and exit pressure Pe is design pressure. 4. A choke valve is also provided, to start the engine from cold. If the exit pressure is more than the designed pressure but less than critical pressure, the flow is not isentropic in the divergent part and it is accompanied by highly irreversible phenomena known as shocks. 19.6. For a nozzle, velocity of the fluid should increase continuously from entrance to exit. In this nozzles are grouped in 3 to 5 or more groups and each group of nozzle is supplied steam controlled by valves. Convergent Nozzle 2. 2. Sign in to download full-size … This leakage of... Slotter Machine - Types, Parts, Operations, Diagram, Specification. 6.7). Types of Steam Turbines. Situation first: It is used when the backpressure is equal or more than the critical pressure ratio. As this lower pressure stream emerges into the higher pressure discharge region, there is a sudden increase in pressure, an act that sets up compression pressure waves, much stronger than sound waves. 2. [gravityform id="1" title="false" description="false" ajax="true"]. Fluid velocity. The flow of the fluid is assumed to be one dimensional. It is a point, where the saturation line meets the initial pressure (P1) line. Thermodynamic and mechanical properties are uniform across planes normal to the axis of a duct. When the back pressure is increased the shock moves upstream and disappears at the nozzle throat where pressure Pe has some value P3. Let us see the nozzle which is fitted at … Hollow cone nozzles-Disc and core type These are used … But in actual case, the friction losses occur. (iii) When exit pressure P2 is equal to critical pressure, the nozzle operates with maximum mass flow rate and the pressure distribution is shown by curve (III). Injectors for pumping feed water to boilers. ME8595 Important Questions THERMAL ENGINEERING II General-Flow Analysis 4. This tells that, for sub-sonic flow, the duct must be convergent. Case Studies in Thermal Engineering 24 (2021) 100833 12 [10] Y. Amini, M. Mokhtari, M. Haghshenasfard, M.B. Turbo machines like steam turbines, water turbines and gas turbines produce power by utilising the kinetic energy of the jets produced by passing high pressure steam, water and gas through the devices called nozzles. Calendar found that the Wilson line approximately follows the 97% dryness line. Let this heat drop be shown as AC instead of AB. Save my name and email in this browser for the next time I comment. 2. Now draw a vertical line through A to meet the final pressure (P2) line. Read, highlight, and take notes, across web, tablet, and phone. Shocks occur only when the flow is supersonic and after the shock the flow becomes sub-sonic and the rest of the diverging portion acts as a diffuser. Nozzle effeciency is defined as: “ The ratio of the actual enthalpy drop to the isentropic enthalpy drop between the same pressures. In nozzle … It also gives information which type of duct should be used for a particular application. In the impulse turbine, the steam is expanded only in fixed nozzles. “ Due to friction between the fluid and the walls of the nozzle within the fluid itself the expansion process is irreversible although still approximately adiabatic. However, the density increases by a large percentage that the velocity decreases, with the result that the computed mass flow of super­saturated steam is greater than the computed flow of equilibrium steam, given the initial state and throat area. Many gas atomizer designs are known. 2. Critical Pressure Ratio 7. Convergent-Divergent Nozzle Convergent Nozzle: A typical convergent nozzle is shown in fig. This jump in pressure outside the nozzle occurs when the back-pressure is above the exit pressure. In other words they also act as the nozzles. Nozzle is an engineering device which will accelerate the fluid and hence fluid velocity or kinetic energy of fluid will be increased while pressure of fluid will be reduced. 19.10. When pressure Pe is equal to inlet pressure Pr there is no flow. Report a Violation 11. If the cross-section of a duct decreases gradually from inlet to exit, the duct is said to be convergent. Privacy Policy 9. (2) To direct the fluid jet at the specific angle known as nozzle angle. Steam turbines may be classified into different categories depending on their construction, working pressures, size and many other parameters. Effect of Friction 8. Since oil is a liquid it has the tendency to 'leak' through every gas/slot it finds during movement. 3. Convergent-Divergent Nozzle. Let us consider a convergent-divergent nozzle as shown in Fig. Content Filtration 6. Welding nozzles are interchangeable and are mounted at the front of the welding gun. The section where cross-sectional area is minimum is called ‘throat’ of the nozzle. When a steadily flowing fluid is decelerated in a duct causing rise in pressure along the stream, then the duct is called a diffuser. Divergent nozzle… Increase in the dryness-fraction of steam. to shaft-engine propulsions, so it is the nozzle to jet propulsion, since it is in the nozzle that thermal energy (or any other kind of highpressure energy source) transforms into kinetic energy of the exhaust, - and its associated linear momentum producing thrust. Friction. Of course the flow should be computed for the throat section since this is where it is limited. At subsonic speeds (Ma<1) a decrease in the area increases the speed of flow. Now the actual expansion of steam in the nozzle is expressed by the curve AB’ (adiabatic expansion) instead of AB (isentropic expansion). Nozzles are used to remove air from a condenser. It is also used for non – compressible fluids. A steam nozzle is a duct or passage of smoothly varying cross-sectional area which converts heat energy of steam into kinetic energy. When discharge from a nozzle is actually measured it is found to be from 2 to 5% greater than the calculated discharge. Hydraulic seals - Definition, Types, Diagram , Function, Failure, Application. Convergent Nozzle 2. 3. 1. … There are following applications of a nozzle are: 1. ... • Type … if the fluid is steam, then the nozzle is called as Steam nozzle. The Mollier Chart shows the isentropic flow (1 -1 – 2) of steam through a convergent-divergent nozzle. Super Saturated or Metastable Flow 10. The divergent portion acts as a super-sonic nozzle with a continuous decrease in pressure and continuous increase in velocity. Nature of the fluid and its state, 6. Solved Problems: 1. This non-equilibrium behaviour as a superheated vapour does not continue indefinitely and at point B, restoration of equilibrium quickly occurs and is after the throat in divergent portion of the nozzle. This is due to low initial velocity. Divergent nozzles slow fluids, if the flow is subsonic, but accelerate sonic or supersonic fluids. Angle of divergence. A nozzle is a device, a duct of varying cross-section area in which a steadily flowing fluid can be made to accelerate by a pressure drop along the duct. But from the first law of thermodynamics, The change in Kinetic energy for unit mass is-. Point A represents a steam in superheated region at pressure P1. 4.25), and internal mixing.The closed nozzle designs are also called close-coupled nozzle designs. A wide variety of spray nozzle applications use a number of spray characteristics to describe the spray.. Spray nozzles … Convergent Nozzle 2. Plagiarism Prevention 5. The fluid stream suffers a loss of momentum while flowing past the blades that is absorbed by the rotating wheel entailing the production of torque. The suction pressure will act on nozzle only. At throat, the velocity is sonic. So when a fluid flows through a nozzle, its velocity increases continuously and pressure decreases continuously. So if the inlet fluid condition is known, we can select the nozzle as below: 1. Note: Nozzle … 2. Steam Nozzles. Today we will learn about what is turbine and types of turbines used in mechanical industries. The arc of admission is limited to 180º or less. Prohibited Content 3. 1. types of nozzle. Image Guidelines 4. The main use of a steam nozzle is in steam turbine, which produces a jet of steam with high velocity. Convergent Nozzle 2. It is a device in which velocity decreases n pressure increases from inlet to … R. Myllymaki, in Welding in Energy-Related Projects, 1984 The Stresses. It is denoted by K, K = Useful Heat Drop / Isentropic Heat Drop. (M) is less than 1. i.e. He also likes to write articles related to the mechanical engineering field and tries to motivate other mechanical engineering students by his innovative project ideas, design, models and videos. The moving blades move as a result of the impulse of steam (caused by the change of momentum) and also as a result of the expansion and acceleration of the steam relative to them. It may be considered as a vertical shaper. In equilibrium flow, the energy released by condensing the molecules is provided for increasing the kinetic energy of the steam as it passes through the nozzle. 1. … 3.3 Types of Nozzles: 1. They are classified as free fall, confined or closed nozzles (Fig. … It is used to measure the discharge of fluid.- e.g. validation of ANSYS for thermal and structural analysis is done first for simple problems, then the analysis done with the nozzle. This expansion is irreversible and gives rise to pressure oscillations as shown by curve (IV). Type 2 is the bullet-shaped nozzle and Type 3 is the simple cone-shaped nozzle, where both types of nozzle … The initial conditions are kept constant and exit pressure P2 is reduced gradually from the initial pressure P1 by a valve. (1) To convert pressure energy and thermal energy into kinetic energy and. This state is called as ‘chocked flow’ or the nozzle is said to be ‘chocked’. Refer Fig. The flow of steam through nozzles may be taken as adiabatic expansion. 1. 5. W‘ Example 18.11. Since the mass of steam which is passed through any section of the nozzle remains’ constant. If the Mach number is less than one, flow is sonic, and the nozzle is convergent. The shape of the nozzle is designed such that it will perform this conversion of energy with minimum loss. Since there is now a sudden decrease in pressure on the jet, expansion waves are initiated. The change in area and curvature along the axis of the duct are gradual. If the cross-section of the nozzle increases continuously from entrance to exit, it is called a divergent nozzle. We will assume heat the nozzle is horizontal, The fluid is just flowing through a duct. By using this convergent nozzle, the flow of the fluid can be increased to sonic velocity. The temperature of the supersaturated steam at B will be below the normal temperature of steam for that pres­sure; this state is known as undercooled state, the amount of undercooling being the difference between the normal temperature and the actual temperature. The convergent-divergent nozzle is used for convert sub-sonic flow into super-sonic flow. Convergent-Divergent Nozzle. d. Nozzle friction losses: These losses are occurred due to the friction in the nozzle. 3. Steam nozzles are of three types, namely convergent nozzle, divergent nozzle, and convergent–divergent nozzle. The condition is shown by case (a). (i) Friction between sides of nozzle (wall of nozzle) and fluid. 8. 1. In this case, the cross-sectional area first decreases from its entrance to the throat and then increases from throat to exit.it is widely used in many types of steam turbines. A duct which decreases the velocity of a fluid and causes a corresponding increase in pressure is a diffuser . Huge Collection of Essays, Research Papers and Articles on Business Management shared by visitors and users like you. d. Nozzle friction losses: These losses are occurred due to the friction in the nozzle. 1. If the cross-section initially decreases and then increases, the duct is called a convergent-divergent nozzle. Increase in discharge by 2 to 5% due to increase in density due to super cooling. But there are two basic types … It is used in a case, where the back pressure is less than the critical pressure ratio. Convergent-divergent nozzles … 2. Disclaimer 8. Content Guidelines 2. are normally obtained by using Mollier Chart. When the steam flows through a nozzle, some loss in its enthalpy or total heat takes place due to friction between the nozzle surface and the flowing steam. If C1, the initial or approach velocity is neglected, then. A steam nozzle is a passage of varying cross section, which converts heat energy of steam into kinetic energy. In the convergent part the velocity of fluid is increased from sub-sonic to sonic condition. During the first part of the nozzle, the steam increases its velocity. At subsonic speeds (Ma<1) a decrease in the area increases the speed of flow. Phenomenon in Nozzles Operating Off the Design Pressure Ratio. A steam nozzle is a passage of varying cross section, which converts heat energy of steam into kinetic energy. ME8595 Important Questions THERMAL ENGINEERING II . The same duct may be either a nozzle … Learn how your comment data is processed. The heat drop (h1 – h2) is known as the isentropic heat drop. Correspond­ing to the fluids used, the nozzles are called steam nozzles, water nozzles and gas nozzles. Thermal … Introduction to Seals : this type of losses is occurred due to the temperature difference between turbine casing and surroundings. Thermal Engineering. In Mollier Chart, 1 -t- 2′ is the actual expansion of steam through nozzle. So the divergent section acts as a sub-sonic diffuser in which the pressure increases and velocity decreases. A steam turbine is a device that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. A spray nozzle is a precision device that facilitates dispersion of liquid into a spray.Nozzles are used for three purposes: to distribute a liquid over an area, to increase liquid surface area, and create impact force on a solid surface. Steam Nozzle major function is to produce steam jet with high velocity to drive steam turbines. The energy conversion is brought about in the following ways: 1. Construction And Working Of Steam Jet Refrigeration System, Venturimeter – Parts, Diagram, Working, Advantages, Application, Centrifugal Compressor – Diagam, Parts, Working, Efficiency, Advantages, Introduction to Bernoulli’s equation and It’s Application, Steam Turbine and Steam Nozzle | Interview Question and Answers, Types Of Cooling Fins | Fin Efficiency, Applications, Advantages, Steam Condenser | Types , Function , Diagram , Advantages. It is the ratio of useful heat drop to the isentropic heat drop. 778 THERMAL ENGINEERING This will result in 0.97% increase in discharge as specific volume will not be aifected by velocity of approach. 5. The smallest section of the nozzle is called the throat. 2. Since the mass of steam which is passed through any section of the nozzle remains’ constant. The fluid stream suffers a loss of momentum while flowing past the blades that is absorbed by the rotating wheel entailing the production of torque. So that Pe/Pt is less than 1 but greater than critical pressure ratio, the velocity increases in the convergent region of the nozzle, but mach number (m) is less than 1 at throat. A convergent-divergent nozzle … The slotter or slotting machine is also a reciprocating type of machine tool similar to a shaper. That the dynamic stress system near the inlet nozzle is complex is not surprising when one considers the geometry of a 150 mm diameter nozzle in a 300 mm diameter header as well as the thermal effects. When Pe is reduced to the pressure denoted by curve (II). If on the other hand the area of the exit section is such that the fluid expands to a pressure at this section greater than that in the discharge region, under-expansion has occurred. Terms of Service 7. Steam Nozzles and Types Nozzle is a duct by flowing through which the velocity of a fluid increases at the expense of pressure drop. Faculty of Mechanical Engineering SMEX1009-THERMAL ENGINEERING Types of Nozzles: 1. Define the term stream nozzle. Rent and save from the world's largest eBookstore. Convergent and Divergent nozzle: Cross-sectional area of nozzle first continuously decreases and then increases from entrance to exit. Size and shape of the nozzle. 9. Correspond­ing to the fluids used, the nozzles are called steam nozzles, water nozzles and gas nozzles. to shaft-engine propulsions, so it is the nozzle to jet propulsion, since it is in the nozzle that thermal energy (or any other kind of highpressure energy source) transforms into kinetic energy of the exhaust, - and its associated linear momentum producing thrust. A typical convergent nozzle is shown in fig. When the velocity of fluid is less than sonic velocity (i.e. Type 1 is therefore selected as a reference nozzle. Increase in final dryness-fraction and increase in enthalpy. First of all, locate the point A for the initial conditions of the steam. Types and Shapes of nozzles, Flow of steam through nozzles… So only in convergent-divergent nozzle, the sub-sonic flow is converted into super-sonic flow. 6. Also if P2 = 0, the mass flow rate is zero. Define nozzle efficiency. Velocity Coefficient 9. Its modern manifestation was invented by Charles … The geometry of this nozzle and its position in the mixing chamber are recommended by an ejector manufacturer for the ejector heat pump. A spray nozzle is a precision device that facilitates dispersion of liquid into a spray.Nozzles are used for three purposes: to distribute a liquid over an area, to increase liquid surface area, and create impact force on a solid surface. A steam turbine converts the energy of high-pressure, high-temperature steam produced by a steam generator into shaft work. If the steam does not condense, then the energy for this increase in kinetic energy come by reduction in the temperature and therefore the steam is called super-cooled. It is best for the expansion in the nozzle to occur to just the right (designed) discharge pressure. This has four rows of 320 nozzles for a total of 1280 nozzles and 1200 dpi resolution. 3. For steam nozzles the values of enthalpy (h1, h2, ht etc.) ME6404 THERMAL ENGINEERING 3.3 Flow Through Nozzles A nozzle is a duct that increases the velocity of the flowing fluid at the expense of pressure drop. The high-velocity steam coming out of the nozzles impinges on the blades mounted on a wheel. The high-pressure, high-temperature steam first expands in the nozzles emanates as a high-velocity fluid stream. 1. when the flow is sub-sonic), the match no. 4. Get Textbooks on Google Play. The pressure-drop from critical pressure to P2 takes place after the nozzle. Here mach number (m) is equal to one at the throat but divergent portion acts as a sub-sonic diffuser in which pressure increases and velocity decreases. A steam nozzle may be defined as a passage of varying cross-section, through which heat energy of steam is converted to kinetic energy. Convergent Nozzle: A typical … Explain various types of nozzles. The flow of the fluid is assumed to be steady flow. Thank you For Visiting. Many gas atomizer designs are known. (Ans. ) And more fuel less air (i.e., rich mixture) will go to engine and engine starts. In supersonic flows (Ma>1), the effect of area changes are different. Where, ht = specific enthalpy at the throat conditions. At this point, the random kinetic energy of the molecules has fallen to a level which is insufficient to overcome the attractive forces of the molecules and some of the slow moving molecules start to form tiny droplets to condensate. 3. 4. Super Saturated or Metastable Flow through Nozzle: The ideal case of isentropic expansion of a superheated vapour to a state in the wet region is shown in T-S diagram and h-s diagram of Fig. ME8595- THERMAL ENGINEERING – II Syllabus 2017 Regulation,ME8595,THERMAL ENGINEERING – II Syllabus 2017 Regulation,ME8595- THERMAL ENGINEERING – II Syllabus ... To understand the concept of utilising residual heat in thermal systems. A wide variety of spray nozzle applications use a number of spray characteristics to describe the spray.. Spray nozzles … Definition of Nozzle 2. 3. Convergent-Divergent Nozzle Convergent Nozzle: A … The moving blades move as a result of the impulse of steam (caused by the change of momentum) and also as a result of the expansion and acceleration of the steam relative to them. Mechanical MCQ Objectives Question and Answers, Mechanical Subjectwise Basic Concept Notes ,Articles, Thermal Engineering - Articles , Notes , Interview Q & A. Sachin is a B-TECH graduate in Mechanical Engineering from a reputed Engineering college. The smallest section of the nozzle … Injectors for pumping feed water to boilers. Nozzle is an engineering device which will accelerate the fluid and hence fluid velocity or kinetic energy of fluid will be increased while pressure of fluid will be reduced. The smallest section of the nozzle is called the throat. This can be best understood with the help of h-s diagram or Mollier chart, as shown in Figure: 1. The energy conversion is brought about in the following ways: 1. We have heard many time the word “turbine”, but most of us don’t know more about It. Your email address will not be published. Types of Nozzles: 1. 3. Diffusers are used in centrifugal compressor. Similar to nozzle, there are three types of diffusers: The given duct will work as a diffuser or a nozzle depending upon the fluid velocity at the inlet of a duct. Divergent Nozzle 3. Types of Nozzle in IC Engine : Pintle Nozzle, Single Hole Nozzle, Multihole Nozzle, Pintaux Nozzle

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