Over expanded and under expanded nozzles, ejector and variable area nozzles, interaction of nozzle flow with adjacent surfaces, thrust reversal. Why are adjustable area jet engine nozzles mostly limited to. Google has not performed a legal analysis and makes no representation. The cycle performance is reported for different mixing section constant diameters. Glover research was performed to optimize highefficiency jet ejector geometry holtzapple, 2001 by varying nozzle. The ejectors tested had a constant exit area and variable primary area to provide nozzle area ratios from 1. Ejector performance with two working fluids r152a and r600a is analysed. A sdvosb service disabled veteran owned small business. By changing the spindle position sp, the area ratio r a can be changed. Conceptual development and cfd evaluation of a high. Theoretical and experimental investigations of different area. Performance evaluation and parametric studies on variable nozzle. Best a generalized ejector model was successfully developed for gas ejector design and performance analysis.
Inventions free fulltext current advances in ejector. Analysis and testing of twodimensional slot nozzle. After exiting the nozzle, it interacts with the secondary flow and is accelerated through an entrainmentinduced effect. Previous 1d analytical models can be derived from this new. Brown variable ejector for iris nozzles 2 sheetssheet 1 filed dec. Ar decides the velocity and pressure of the driving flow at the nozzle exit. Impulse and reaction principles, compounding, velocity diagrams for simple and multistage turbines, speed regulationsgovernors and nozzle governors. A variable area nozzle helps to adjust the exit pressure of the combustion gases to ambient pressure. By reducing the nozzle throat area, the primary mass flow rate also decreases. All of the archive files of this validation case are available in the unix compressed tar file eject. Analysis and testing of twodimensional slot nozzle ejectors. The variable area ratios of ejectors a 2 a t were used with a range from 10.
The variable area mixing ejector has been developed based on a onedimensional. In order to overcome this problem, an advanced ejector was developed that changes its. Ejector extension cooling for exhaust nozzle united. This invention relates to a system for cooling the side wall and flaps of a variable area nozzle for a gas turbine engine and particularly to a system that includes a cooling extension for an ejector and the. The principle of operation of ejectors is based on the venturi effect of a convergingdiverging nozzle to convert the pressure energy of a motive fluid primary flow to kinetic energy to entrain a suction fluid secondary flow, and then recompress the mixed fluids by converting kinetic energy back into pressure energy figure 1. Analysis on performance characteristics of ejector with. Effect of nozzle exit position nxp on variable area. All stainless steel vacuum ejector smc corporation. The ejector essentially consists of an assembly comprising of nozzle, converging section, mixing tubethroat and diffuser. A supersonic ejector utilizes the energy and momentum of a primary motive jet to entrain and compress a secondary coflow. Variable area nozzles are used for adjusting the exit area for different operating conditions of the engine. The variable area mixing ejector has been developed based on a. It is a pure aerodynamic device that has no moving parts and the flow is brought about by just gas dynamics of the two flows confined within a variable area duct.
Thrust nozzles for supersonic transport aircraft citeseerx. Pdf effect of the nozzle exit position on the efficiency of. Variablearea ejectors, plug nozzles, and modifications of. This paper focuses on a convergent nozzle ejector and proposes a lumped parameter model with variable efficiencies provided by a cfd analysis. Ejector refrigeration is a promising technology for the integration into solar driven cooling systems because of its relative simplicity and low initial cost. A variable formulation for the ejector efficiencies can be obtained by literature data 17, experimental investigations 18 or cfd analysis 19,20. The thermophysical properties of librh2o solution are estimated using the.
The variable area mixing ejector has been developed based on a one. So this is indeed a related concept and helps to optimize performance both at low and high. The method assumes a constant rate of change of momentum within the duct. When they leave the turbine, the combustion gases have still some remaining pressure which is converted into speed by a convergent contour of the nozzle. The variable area mixing ejector has been developed based on a one dimensional constant rate momentum change. The very latest ejector designs are now available at the click of a. Variable flow ejectors are based on proven gea jet pump. Tests were conducted at nozzle pressure ratios ranging from.
Maximum turbojet engine size was desired because of takeoff and transonic thrust requirements. As the spindle tip travels forward, the primary nozzle throat area decreases, and consequently r a increases. Optimization of a highefficiency jet ejector by computational fluid dynamics software. The variable geometry was done by a movable spindle. A test program was run to provide twodimensional ejector test data for verification of the computer analysis. Variable area jet nozzle for noise reduction using shape. Comparison of predicted and experimental wall temperatures. Authority us united states prior art keywords exhaust nozzle flaps actuating flap means prior art date 19650427 legal status the legal status is an assumption and is not a legal conclusion. Comparison of cfd and experimental performance results of a. If the amount of leakage is known based on the effective sectional area of the side with the leakage, the vacuum pressure can be estimated in accordance with the ejectors flowrate characteristics. The results from the trnsys simulation of dennis 20 showed that the variable geometry ejector achieved an 8% higher solar fraction than the fixed geometry one. Review on ejector efficiencies in various ejector systems.
A that the entry speed can be neglected, only modifies the flow inside the nozzle, but not the exit conditions. Pdf effect of the nozzle exit position on the efficiency of ejector. Variable area exhaust nozzle download pdf info publication number us3295764a. Comparison of cfd and experimental performance results of. R600a is a good choice for working fluid in the range of tested conditions. As a specific result, they found that for a fixed geometry, the ejector is very sensitive to variations in operating conditions which can have an adverse effect on the ejector performance. Controlling ejector performance pumps operating on the ejector principle are in use on many processes.
Preliminary design and computational analysis of an ejector. The variable area mixing ejector has been developed based on a onedimensional constant rate momentum change. If the exit diameter of nozzle is 25 mm, find the number of. A tertiary inlet ejector nozzle for a jet engine having spaced outer and inner casings forming a cooling flow passage around the engine, l l. While both these areas are fixed in many engines i. A number of numerical and experimental studies have been devoted to the modeling of highperformance steadyflow ejectors in different fields of application. Initially sun 19 suggested that an ejector should have a variable area ratio with a variable length in order to work for a full range of condenser and generator temperatures. Therefore, they react to control impulses in a manner peculiar to their. The optimum length and diameter of the throat section, the nozzle position, and the radius of the inlet curvature before a convergence section in a constantarea jet ejector design are investigated for. Six different area ratios of ejector using air as working fluid in this study were proposed and tested experimentally. Propelling nozzles may have a fixed geometry, or they may have variable. Unit iii unit iii steam nozzles and turbines flow of steam through nozzles, shapes of nozzles, effect of friction, critical pressure ratio,supersaturated flow. Considerable leakage from the suction surface if a workpiece is made of porous material or if there is air leakage from the area between the pad and the workpiece, use a nozzle with a.
A motive nozzle needle allows precise adaption on varying. Mar 20, 1973 an ejector as claimed in claim 1 including an elongated fixed plug disposed in said duct in axial alignment with said elongated movable plug and defining with said duct a diffuser nozzle. Due to the symmetric nature of the ejector nozzle and mixing section, only half of the ejector was modeled numerically. Review on ejector efficiencies in various ejector systems fang liu shanghai university of electric power. Oct 24, 2019 a number of numerical and experimental studies have been devoted to the modeling of highperformance steadyflow ejectors in different fields of application. Variable area nozzles are used for adjusting the exit area for different. Analysis of hybrid ejector absorption cooling system. Theoretical and experimental investigations of different.
We proceed now to develop equations that help us determine. Development and performance of an advanced ejector cooling. The variable area fan nozzle tries to do for the fan flow what the regular nozzle does for the core flow of a jet. The variable area iris nozzle consists of a series of moving, overlapping petals with a nearly circular nozzle crosssection and is convergent to control the operation of the engine. A test rig was also assembled in order to test the ejector performance under controlled laboratory conditions and to elaborate a control algorithm for the variable geometry. The areas of both the propelling nozzle and turbine nozzle set the mass flow through the engine and the maximum pressure. The results indicated that the entrainment ratio, pressure recovery ratio and critical area ratio were strongly affected by both primary and secondary pressures. A few literature researchers have studied the effect of nozzle diameter on jet ejector performance. The major drawback of such a system is associated with its relatively low coefficient of performance cop under variable operating conditions. Two sets of ejectors a and c are studied and examined depend on the kind of nozzle. Effect of nozzle exit position nxp on variable area mixing.
The files can then be accessed by the commands uncompress eject. For this test it was required that the nozzle be held at a well defined minimum area under all loads, but also it must be able to hold a progra mmed area up to 20% larger as. An integrated lumped parametercfd approach for offdesign. Effect of the nozzle exit position on the efficiency of ejector cooling system using r4a. Pdf effect of nozzle exit position nxp on variable area mixing. Since an ejector has no valves, rotors, pistons or other moving parts, it is a relatively lowcost component is easy to operate and requires relatively little maintenance. Why are adjustable area jet engine nozzles mostly limited to military use.
Research and technology development activities were carried out at the rollsroyce university technology center for high mach propulsion, purdue university. Why are adjustable area jet engine nozzles mostly limited. A prototype was constructed with two independent variable geometrical factors. The definitions of overall ejector efficiency and ejector component efficiencies in literature are. A propelling nozzle is a nozzle that converts the internal energy of a working gas into. The study is focused on evaluating the feasibility of an ejector whose nozzle area is adjustable while the rest of the ejector dimensions are fixed, thus being more feasible than completely variable geometry ejectors. This invention relates to a system for cooling the side wall and flaps of a variable area nozzle for a gas turbine engine and particularly to a system that includes a cooling extension for an ejector and the option of including means for varying the exit flow of the ejector. The efficiency of the ejector cycle is very sensitive to the ejector efficiency. Ejectors are essentially a fixed capacity device since the diffuser area is constant. In an increasing number of applications it is necessary to apply controls. Preliminary design and computational analysis of an. The ees machine model program is run to thermodynamically analyze the proposed hybrid singleeffect absorption refrigeration system. Selecting an eductor the venturi is a teeshaped device that passes fluid through a restricting nozzle see figure 9, increasing its flow velocity and. This invention relates to jet pumps and more particularly to an ejector having variable primary nozzle area and mixing chamber area.
Read analysis on performance characteristics of ejector with variable arearatio for multievaporator refrigeration system based on experimental data, applied thermal engineering on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. If the aircraft is to fly at supersonic speeds, the afterburner nozzle may be followed by a separate divergent nozzle in an ejector nozzle configuration, as below. The device where the liquid flow and the airflow come into contact with each. The primary nozzle, which is illustrated in detail, has an inlet diameter d 1 of 15 mm, a throat diameter d t of 4 mm and an exit diameter d 2 of 6 mm.
Highlights a numerical analysis of two ejectors with variable geometry is presented using cfd. An ejector as claimed in claim 1 wherein said movable plug concomitantly changes the area of the primary nozzle and the longitudinal crosssectional area. Advantages of the ejector nozzle are relative simplicity and reliability in cases. Pdf the benefits of variable area fan nozzles on turbofan. Nozzle design nozzle geometry affects ejector operation. Circuit diagram exe v p vacuum ejector inline type zu series rohs type high vacuum type large flow type model zu05s zu07s zu05l zu07l nozzle diameter mm 0. A numerical analysis of novel liquidgas jet ejector. When afterburning engines are equipped with a cd nozzle the throat area is. With high and low pressure flow loops, along with multiphase and sand slurrry capabilities, we can guarantee the performance of your ejectors. Cfd study of a variable area ratio ejector using r600a and. A primary converging nozzle with a discharge geometry of 0. In a steamjet ejector, the suction chamber is connected to the vessel or pipeline that is to be evacuated under vacuum.
Optimal spindle positions are presented depending on operating conditions. The maximum allowable engine size to avoid reverse flow in the ejector increases slightly with the primary nozzle area ratio. Variable area ejector results in better performance than fixed geometry design. Numerical investigation of a refrigeration ejector. This study presents a comprehensive numerical, experimental study and analysis on the effect of nozzle exit position nxp on variable area mixing ejector. Pdf effect of the nozzle exit position on the efficiency. Jul 01, 2014 read analysis on performance characteristics of ejector with variable area ratio for multievaporator refrigeration system based on experimental data, applied thermal engineering on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. According to the bernoullis principle, when a motive fluid is pumped through the nozzle of a gasliquid ejector at. Brown variable ejector for iris nozzles 2 sheetssheet 2 inventor. Variable flow ejectors are based on proven gea jet pump technology and often used for heat recovery. Study on the performance of a variable geometry ejector. The mixing between both flows takes place along a constantarea duct called the mixing chamber where complex interactions between the mixing layer. The present experimental study is performed on the basis of an ejector with variable area ratios.