The numerical simulations of compressible flow passing through a 2d convergentdivergent nozzle with a fixed geometry and different nozzle pressure ratios are presented. Using above relations, we calculated both the nozzle thrust coe cient and the discharge coe cient for all the cases in the instance. In a convergent nozzle, there is an increase in velocity. The upstream length convergent section of the nozzle is 150mm with convergence angle 7. The nozzle exits were located at the left edge of the windows so that the complete shock cell structure could be observed as shown in fig. There is a relatively simple equation that you can use to calculate the throat area of the nozzle a for 1 dimensional round crosssection nozzle isentropic flow the flow so smooth that the gas entropy doesnt change during its entire journey. Alexandria university faculty of engineering mechanical engineering department under the supervision of dr.
As a liquid enters the smaller crossarea, it needs to accelerate because of the production of mass. Convergent divergent nozzle shock wave cfd results youtube. The coding was done in matlab to obtain the contour of the divergent section for seven different exit mach numbers viz. To get a basic feel for the behavior of the nozzle imagine performing the simple experiment shown in figure 2. If the steam floe rate is 1 kgs and the initial velocity of steam is negligible, find the minimum area of the nozzle.
In the divergent parts, the friction loss may be taken as 0. A convergingdiverging nozzle with a centered throat. Energy is required for compression and energy in lost in any nozzle. The program that i use for the programming is matlab. A design method for a supersonic axisymmetric nozzle for use in. The convergent length should be very small because the flow is accelerated, but the wall angle of the divergent should be 7 degrees or less, in order to no produce boundary layer detachment. The flow of air through three convergentdivergent nozzles was studied theoretically.
To quantify variation in the minimum length of the nozzle divergent section with respect to the exit mach number, a throat of constant height 0. The experiment was conducted using computational fluid dynamics and the results produced were compared with the theoretical results to present the accuracy of the. Fluent compressible flow in a nozzle simcafe dashboard. Quasionedimensional flow in convergentdivergent nozzles. Design and numerical investigation to visualize the fluid flow and. Cfd results for shock wave inside the divergent part of the convergent divergent nozzle. To keep up a consistent measure of liquid traveling through the confined bit of the spout, the liquid must move faster.
This nozzle configuration is called a convergentdivergent, or cd, nozzle. Alexandria university faculty of engineering mechanical engineering department under the. Consider air flowing at highspeed through a convergent divergent nozzle having a circular crosssectional area, a, that varies with axial distance from the throat, x, according to the formula a 0. Media in category convergent divergent nozzles the following 27 files are in this category, out of 27 total. The convergent nozzles are used to increase fluid velocity and thus convert most of the fluid energy into its. Flow analysis in a convergentdivergent nozzle using cfd. Numerical investigation of transonic resonance with a convergentdivergent nozzle chingy. How to calculate the length of convergent divergent nozzle. Convergent divergent 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. In a convergent nozzle, there is an increase in velocity and. In a cd nozzle, the hot exhaust leaves the combustion chamber and converges down to the minimum area, or throat, of the nozzle.
Values of the index n and the critical pressure ratio r, for different fluids are given in the table below. The reference length, the nozzle height at the throat, is constant at 22. Over and under expanded jets have been studied a lot in the past, so you can find lots of papers on how to setup and solve such problems. Apr 11, 2015 cfd results for shock wave inside the divergent part of the convergent divergent nozzle.
I am also simulating convergent and divergent nozzle, my problam convergent is subsonic condition and throat sonic, divergent supersonic condition. Convergent divergent nozzle flow velocity and area equation. It gives the profile for the divergent part of the cd nozzle. But the design of trinozzle is optimized to have high expansion coefficient than single nozzle without altering the divergent angle. Develop a matlab code that performs a quasi 1d study to size the nozzles exittothroat area ratio. The downstream geometry length 117mm is varied with nozzle. To maintain a constant amount of fluid moving through the restricted portion of the nozzle, the fluid must move faster. Cfd analysis of convergent divergent supersonic nozzle.
This is a very simple program for designing convergent divergent cd nozzle. Two different nozzles were used with a convergent nozzle and a convergentdivergent nozzle. The convergent divergent nozzle finds application in many areas of industry and technology. Zaman national aeronautics and space administration glennresearchcenter cleveland,ohio445 abstract at pressure ratios lower than the design value, convergentdivergent cd nozzles often undergo a. Us7032835b2 convergentdivergent nozzle with modulated. Apr 12, 2015 andres adam oriol crespo joan palleja video about our second assignment that will probably bore you if you are not part of the class.
The throat size is chosen to choke the flow and set the mass flow rate through the system. The cd nozzle exhausts this air into cylinder b, which takes the place of the tank. The nozzle is assumed to have impermeable and adiabatic walls with a flow straightener in the upstream side and is connected to a plenum surrounding the nozzle geometry and. Numerical investigation of transonic resonance with a. This paper aims to study the behavior of flow in convergent divergent nozzle by analyzing various parameters like pressure, temperature and velocity using computational fluid dynamics softwarec. As the nozzle transitions between positions, the divergent flap seals move relative. Our predictions, in comparison with the experimental measurements, are shown in the next subsection. Computational results are in good agreement with the experimental results taken from the literature. Supersonic flow in cdnozzles presents a rich behaviour, with shock waves and expansion. Oct 10, 2015 this is a very simple program for designing convergent divergent cd nozzle.
A convergentdivergent nozzle is capable of producing supersonic flow, but that is not what you want in an air intake. Convergent divergent nozzle is designed for attaining speeds that are greater than speed of sound. Modeling and simulation of convergentdivergent nozzle. It is used to accelerate a hot, pressurized gas passing through it to a higher supersonic speed in the axial thrust direction, by converting the heat energy of the flow into kinetic energy. A convergingdiverging nozzle with reservoir pressure fixed. Cylinder a contains air at high pressure, and takes the place of the chamber. Convergentdivergent nozzle flow velocity and area equation and calculator throat velocity equation.
Convergent divergent nozzle flow velocity and area. These results were further plotted comparing them with. Convergent divergent nozzle flow velocity and area equation and calculator throat velocity equation. Convergentdivergent nozzle spectreeng automotive 11 jul 06 15. The coding was done in matlab to obtain the contour of the divergent section for seven different. A convergentdivergent nozzle has an exit mach number of 1.
Design and numerical simulation of convergent divergent nozzle. The convergent parts of the nozzle are sharp and frictionless. Apr 04, 20 it seems to me that no matter what convergent nozzle is used, it will get choked exit air will be sonic if the inlet pressure is more than about 2 times the outlet pressure so, for a convergingonly nozzle or a straight tube with no area change, the critical pressure ratio of 0. Please note these problems are difficult to solve even when inviscid isentropic flow is assumed due to the resulting complex wave structure e. The nozzle will become choked even if you eliminated the throat altogether and just had a converging nozzle. Pdf cfd analysis of convergentdivergent and contour nozzle. Here we use a converging diverging nozzle to connect two air cylinders. Flow simulation of a two dimensional rectangular supersonic. It generally means the ability to give the correct answer to standard questions that do not require significant creativity, for instance in most tasks in school and. Modeling and simulation of convergentdivergent nozzle using. I am also simulating convergent and divergent nozzle, my problam convergent is subsonic condition and throat sonic,divergent supersonic condition. In the present paper, flow through thetrinozzle and.
Convergent and divergent nozzle essay example graduateway. Part 2 of the work is on prediction of optimal axial gap convergent divergent nozzle study is carried out by using a finite volume commercial code, fluent 6. May 05, 2015 a nozzle is a relatively simple device, just a specially shaped tube through which hot gases flow. Volume 4 flow analysis in a convergentdivergent nozzle using cfd. I am currently working on the simulation of the flow through a convergentdivergent nozzle at different back pressures as a part of a project at the university. Matlab programs for computation of isentropic compressible flow. As a fluid enters the smaller crosssection, it has to speed up due to the conservation of mass. Convergentdivergent nozzle article about convergent. The area ratio is accurate for mach number m up to 5. Experimental and analytical studies on the shock wave. Convergentdivergent nozzle automotive engineering other.
The agreement is excellent for the quantities compared. Request pdf design and numerical simulation of convergent divergent. How to design a convergentdivergent supersonic nozzle. What are the functions of divergent and convergent nozzle. For isentropic flow in a convergingdiverging nozzle the ratio of local duct area to the area at the throat is uniquely related to the value of ma. The onedimensional inviscid isentropic flow in a convergent divergent nozzle is a classical text book problem which can be further solved by. A nozzle system includes a multiple of circumferentially distributed convergent flaps, divergent flaps and interflap seals which circumscribe an engine centerline and define the radial outer boundary of a gas path. Assessment of turbulence modeling for gas flow in two. Nozzle geometry, expansion ratios, flow and boundary conditions have been drawn on the basis of the literature survey. This nozzle configuration is called a convergent divergent, or cd, nozzle. The coding was done in matlab to obtain the contour of the divergent section. Based on user values for the nozzle pressure ratio, nozzle area ratio, and specific heat ratio of the gas, the flow inside the nozzle is plotted, showing shocks and. It seems to me that no matter what convergent nozzle is used, it will get choked exit air will be sonic if the inlet pressure is more than about 2 times the outlet pressure so, for a convergingonly nozzle or a straight tube with no area change, the critical pressure ratio of 0.
Consider air flowing at highspeed through a convergentdivergent nozzle having a circular crosssectional area, a, that varies with axial distance from the throat, x, according to the formula a 0. I am currently working on the simulation of the flow through a convergent divergent nozzle at different back pressures as a part of a project at the university. Nozzles are actually used to modify the flow of a fluid i. 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. Simulation of expansion is carried on ansys fluent 14software using. This is a very simple program for designing convergentdivergent cd nozzle. It is used to accelerate a hot, pressurized gas passing through it to a higher supersonic speed in the axial thrust direction, by converting the heat energy of the. The onedimensional inviscid isentropic flow in a convergentdivergent nozzle is a classical text book problem which can be further solved by. Ramjets and rockets typically use a fixed convergent section followed by a fixed divergent section for the design of the nozzle. Steam expands in a set of nozzle from 10 bar, 300 0c to 1 bar.
A cfd analysis of compressible flow through convergent. Design of a twodimensional supersonic nozzle for use in wind. In a steady internal flow like a nozzle the mach number can only reach 1 at a minimum in the cross. Each divergent flap includes a multiple of cooling channels with respective intakes and outlets. The convergent nozzle is a spout that begins large and gets smaller, an abatement in crosssectional region. Andres adam oriol crespo joan palleja video about our second assignment that will probably bore you if you are not part of the class. The nozzle geometry modeling and grid generation has been done using gambit 2. Output of matlab code the code that follows gave this output. The present work focuses on the cfd simulation of a convergentdivergent nozzle undergoing compressible.
An initial design of the nozzle is made from the method of characteristics. The convergentdivergent nozzle finds application in many areas of industry and technology. A divergent nozzle is used to increase the pressure and thus produce high thrust like aircraft jet engines or rocket propulsion engines. The present work focuses on the cfd simulation of a convergent divergent nozzle undergoing compressible. Nozzle is defined as a device intended to control the speed and direction, or alteration of a liquid stream particularly to expand speed as it exits or enters an encased chamber or pipe. Convergent thinking is a term coined by joy paul guilford as the opposite of divergent thinking. A convergent nozzle is a nozzle that starts big and gets smallera decrease in crosssectional area. Instructions for matlab simulation of quasi1d nozzle flow. Creation of twodimensional geometry of the nozzle and meshing is done on workbench of ansys 14. The choking flow in micronanochannel convergentdivergent nozzle for different mach numbers is simulated using dsmc, which is generally used to simulate.
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