Lecture notes compressible fluid dynamics mechanical. Two broad classes of viscous ow will be illustrated in this. The steam possessesa very high velocity at the end of the expansion, and the enthalpy decreases as. Nozzles and diffusers efficiency and critical pressure nptel. To enable the pressure distribution through the nozzle to be plotted, a search tube or probe of stainless steel may be traversed along the axis of the nozzle. For the love of physics walter lewin may 16, 2011 duration. Calculation of flow through nozzles and orifices neutrium. Jun 12, 2014 the exit velocity, pressure, and mass flow through the nozzle determines the amount of thrust produced by the nozzle. There are many types of losses of head for flowing liquids such as friction, inlet and outlet losses. This form is used to calculate the flow rate of a nozzle given the pressure. Adiabatic flow through nozzles but the actual process is irreversible adiabatic. Mod01 lec31 choking in a converging nozzle youtube. View notes lecture5nozzlesanddiffusers from smbs 12 at vellore institute of technology.
Isentropic flow through convergingdiverging nozzles nptel. Nozzles and mouthpieces head loss pipes fluid mechanics. Part 1 basic principles of fluid mechanics and physical. There are, of course, losses in the nozzle itself, and the actual velocity of discharge will be less than the theoretical value by one to five percent. If the flow through nozzle is isentropic find the number of nozzles and steam. The flow through oblique cut laval nozzle is the same as the supersonic flow around an obtuse angle. Unit iii unit iii steam nozzles and turbines flow of steam through nozzles, shapes of nozzles, effect of friction, critical pressure ratio,supersaturated flow.
Convergentdivergent type of nozzles are mostly used for supersonic flows because it is impossible to create supersonic flows mach number more than one in convergent type of nozzle and therefore it restricts us to a limited amount of mass flow through a. Oct 15, 2016 nozzle is a duct by flowing through which the velocity of a fluid increases at the expense of pressure drop. In the case of a simple concentric restriction orifice the fluid is accelerated as it passes. Because pressure cannot travel upstream through the supersonic flow, the exit pressure can be. This article provides calculation methods for correlating design, flow rate and pressure loss as a fluid passes through a nozzle or orifice. The flow of steam through nozzles may be takenas adiabatic expansion. In an axial flow turbine, the flow enters and leaves in the axial direction. Lecture5nozzlesanddiffusers adiabatic flow through. Types of nozzles the axisymmetric convergentdivergent bell nozzle that has been used as the example to this point is the standard for rocket nozzles, for several reasons. Nozzle requirements calculators washington state university.
Lowering the exit static pressure further will not increase the mass flow rate through the nozzle. The statement of the numerical is in nozzles of a 100 kilopascal kilo watt capacity. Compressible flow through nozzle when an incompressible fluid passes through a converging nozzle with particular velocity then the exit velocity depends only on. Lecture series on steam and gas power systems by prof. Compressible flow compressible flow compressible flow part 4 of 4 choked flow this video discusses choked flow, its importance and critical pressure. However, for accurate analyses when density variations are to. Flow calculating shock position in cd nozzle how do we calculate the position of a normal shock in a convergingdiverging cd nozzle. Whenever a gas is forced through a tube, the gaseous molecules are deflected by the tubes walls. This expansion fan is developed on shortly side of the nozzle. Impulse and reaction principles, compounding, velocity diagrams for simple and multistage turbines, speed regulationsgovernors and nozzle governors. As we know that for the flow through a nozzle the change in enthalpy dh cdc change in kinetic energy and from momentum equation we have write that.
Vtunptelnmeict project progress report the project on. A nozzle is often a pipe or tube of varying cross sectional area, and it can be used to direct or modify the flow of a fluid liquid or gas. Jul 23, 2012 for the love of physics walter lewin may 16, 2011 duration. In the impulse type turbine blade profile the entire enthalpy drop occurs in the nozzle reaction 0. The flow mechanism is similar to that for the orifice see flow through a sharpedged orifice. The major loss is that due to frictional resistance of the. Critical flow nozzles are also called sonic chokes. Introduction to fluid machines and compressible flow. A nozzle is a device designed to control the direction or characteristics of a fluid flow especially to increase velocity as it exits or enters an enclosed chamber or pipe. All gases flow from upstream higher pressure sources to downstream lower pressure sources. Marsch said he thought that flow through nozzles should be merged with nozzle. Fluid mechanics phenomena in rocket nozzles some features.
Unit 4 flow through nozzles velocity and heat drop, mass discharge through a nozzle, critical pressure ratio and its significance, effect of friction, nozzle efficiency, supersaturated flow, design pressure ratio. The differential pressure sensor attached between points 1 and 2 records the pressure difference p1p2 between these two points which becomes an indication of the flow rate of the fluid through the pipe when calibrated. This calculator uses this formula to determine the flow. Introduction it is assumed that the head h is the head behind the nozzle, and that all pipeline and valve losses have been accounted for elsewhere. If there is supersonic flow inside a oblique cut nozzle then the stream of the gas is deviated through an expansion fan from the nozzle axis. Introduction to fluid machines and compressible flow by prof. Most of the analysis we considered so far neglected density variations.
There are two types of axial flow turbine blade profile design. Pressure drop devices based on bernoulli principle a venturi b orifice plate c pitot tube 2. Introduction to fluid machines and compressible flow online. The maximum gas flow through a nozzle is determined by critical pressure. It is used to measure flow rates of the liquid discharged into the atmosphere. No one objected to that idea, although admittedly it was only out there for a few days. Studies will be made on how to express losses caused by a. Method of characteristics pdf effects of particles in nozzle flow pdf. Introduction to fluid machines, and compressible flow prof. Though geometrically different from an orifice plate, a flow nozzle is conceptually similar to it. Here velocity at exit is 500 ms which is more than sonic velocity thus nozzle shall be converg ingdiverging nozzle as shown. Find the nozzle requirements for a given pressure or flow rate.
Nozzles and orifices are often used to deliberately reduce pressure, restrict flow or to measure flow rate. Converging nozzle in a subsonic flow will have decreasing area along the flow direction. This form is used to calculate the needed diameter of a nozzle for a specific pressure and flow rate. Nelson fcn flow control nozzle uneven water distribution through your sprinkler system may be caused by field elevation difference, excessive pipe friction loss or variations in pump pressure. To accelerate a flow beyond sonic velocity it is first necessary to reduce the flow area. Compressible flow through a nozzle diffuser interactive simulation describes how to use an interactive simulation that models flow through an ideal nozzle or diffuser. A small crosshole in the search tube connects with a highgrade pressure gauge, which registers the pressure at any point in the nozzle. The nelson fcn flow control nozzle is designed to automatically compensate for these factors, allowing you to achieve a more uniform application of. In addition, the pressure of the gas at the exit of the expansion portion of the exhaust of a nozzle must not be too low. Flow through pipes 71 friction losses of head in pipes 72 secondary losses of head in pipes 73 flow through pipe systems 71 friction losses of head in pipes. Nozzles are actually used to modify the flow of a fluid i. During the flow of steam through the nozzle, heat is neither supplied nor rejected. The theory of the nozzles be can use for calaculation of a flow through a group of turbine stages at change of state of the gas in front of or behind this group of the stages.