Effect of Geometric Parameters on the Performance of a Radial Flow Pressure Exchange Ejector

2010 ◽  
Author(s):  
Muhammad Umar ◽  
Charles A. Garris
Keyword(s):  
High Pressure ◽  
Radial Flow ◽  
Energy Levels ◽  
Cone Angle ◽  
Interface Pressure ◽  
Complex Flow ◽  
Transfer Energy ◽  
Two Fluids ◽  
Flow Pressure ◽  
Pressure Exchange

The “Pressure exchange” is a novel concept in turbomachinery whereby two fluids, at different energy levels, come in direct contact with each other to transfer energy and momentum between them through non-steady interface pressure forces. The rotating jets of the high pressure primary fluid, often referred to as pseudoblades, resemble solid blades on the impeller of a conventional turbomachine. The low pressure secondary fluid, ahead of the pseudoblades, is pressurized by the action of interface pressure forces. The current paper seeks to provide an insight into the complex flow phenomena occurring inside the radial flow pressure exchange ejector. This research presents the results of the first successful numerical simulation to explore the effects of spin angle, rotor cone angle and number of nozzles on the performance of a radial flow pressure exchange ejector. If this new concept is shown to be viable for gas compression at sufficiently high pressure ratios, then, in refrigeration applications, it would enable environmentally benign refrigerants to replace the harmful chlorofluorocarbons (CFC) and reduce the effluence of greenhouse gases. Applications in many other areas, where conventional ejectors are currently used, are also possible.

Effect of Fluid Dynamic Parameters on the Performance of a Radial Flow Pressure Exchange Ejector

2012 ◽  
Author(s):  
Muhammad Umar ◽  
Charles A. Garris
Keyword(s):  
Radial Flow ◽  
Fluid Dynamic ◽  
Pressure Ratio ◽  
Energy Levels ◽  
Interface Pressure ◽  
Complex Flow ◽  
Transfer Energy ◽  
Two Fluids ◽  
Flow Pressure ◽  
Pressure Exchange

The “Pressure exchange” is a novel concept in turbomachinery whereby two fluids, at different energy levels, come in direct contact with each other to transfer energy and momentum between them through non-steady interface pressure forces. The rotating jets of the high pressure primary fluid, often referred to as pseudoblades, resemble solid blades on the impeller of a conventional turbomachine. The low pressure secondary fluid, ahead of the pseudoblades, is pressurized by the action of interface pressure forces. The current paper seeks to provide an insight into the complex flow phenomena occurring inside the radial flow pressure exchange ejector. This research presents the results of the first successful numerical simulation to explore the effects of primary to secondary total pressure ratio and primary to secondary total temperature ratio on the performance of a radial flow pressure exchange ejector.

On Mutual Deflection for the Radial Rotating Jet Pressure Exchange Mechanism

2009 ◽  
Author(s):  
Muhammad Umar ◽  
Charles A. Garris
Keyword(s):  
High Pressure ◽  
Near Field ◽  
Energy Levels ◽  
Mixing Layer ◽  
Angular Deviation ◽  
Interface Pressure ◽  
Complex Flow ◽  
Transfer Energy ◽  
Pressure Exchange ◽  
Secondary Fluid

The “Pressure exchange” is a novel concept in turbomachinery whereby two fluids, at different energy levels, come in direct contact with each other to transfer energy and momentum between them through non-steady interface pressure forces. The rotating jets of the high pressure primary fluid, often referred to as pseudoblades, resemble solid blades on the impeller of a conventional turbomachine. The low pressure secondary fluid, ahead of the pseudoblades, is pressurized by the action of interface pressure forces. The current paper seeks to provide an insight into the complex flow phenomena occurring inside the radial flow pressure exchange ejector. The primary mechanisms controlling the process are pressure exchange and mixing. The angular deviation, between an actual pseudoblade and the pseudoblade with no secondary fluid, was calculated for the first time. The results revealed that the angular deviation is small in the near field, where pressure exchange dominates, and becomes larger in the far field as the mixing layer tends to grow. If this new concept is shown to be viable for gas compression at sufficiently high pressure ratios, then, in refrigeration applications, it would enable environmentally benign refrigerants to replace the harmful chlorofluorocarbons (CFC) and reduce the effluence of greenhouse gases. Applications in many other areas, where conventional ejectors are currently used, are also possible.

On Length Scales for the Radial Rotating Jet Pressure Exchange Mechanism

2008 ◽  
Author(s):  
Muhammad Umar ◽  
Charles A. Garris
Keyword(s):  
Momentum Transfer ◽  
Near Field ◽  
Exchange Process ◽  
Energy Levels ◽  
Mixing Layer ◽  
Complex Flow ◽  
Transfer Energy ◽  
Length Scales ◽  
Pressure Exchange ◽  
Energy And Momentum

The crypto-steady rotating jet pressure exchange ejector is a novel concept in turbomachinery where two fluids, at different energy levels, come in direct contact with each other to transfer energy and momentum between them through non-steady interface pressure forces. The current paper seeks to provide an insight into the complex flow phenomena occurring inside the radial flow pressure exchange ejector. The primary mechanisms controlling the process are pressure exchange and mixing. This paper will seek to discriminate between energy transfer by each respective mechanism. The energy and momentum transfer in the near field is shown to be mainly due to the pressure exchange process, as the mixing layer does not develop substantially in this region. As the radius increases, the mixing layer tends to grow and the energy and momentum transfer is governed by the mixing process. As a consequence, the length scales of the pressure exchange zone are small, thus making the pressure exchange ejector more compact in size. The paper will delineate between the two length scales. If this new concept is shown to be viable for gas compression at sufficiently high pressure ratios, then, in refrigeration applications, it would enable environmentally benign refrigerants to replace the harmful chlorofluorocarbons (CFC) and reduce the effluence of greenhouse gases. Applications in many other areas, where conventional ejectors are currently used, are also possible.

Flow-Field Analysis and Performance Prediction of Pressure-Exchange Ejector

2011 ◽  
Vol 236-238 ◽  
pp. 1587-1592 ◽  
Author(s):  
Wen Jing Zhao ◽  
Da Peng Hu ◽  
Pei Qi Liu ◽  
Yu Qiang Dai ◽  
Chun Rong
Keyword(s):  
Numerical Model ◽  
Flow Field ◽  
Field Analysis ◽  
Pressure Waves ◽  
Transfer Energy ◽  
Two Fluids ◽  
Working Cycle ◽  
Rotary Speed ◽  
Pressure Exchange ◽  
Opening And Closing

In order to transfer energy between two fluids directly and more efficiently, a novel pressure-exchange ejector was designed, and a multi-period numerical model considering leakage and gradual opening and closing of the ports was set up. The numerical model was validated by experiment and results proved that it could capture the shock wave accurately and predict the performance of pressure-exchange ejector effectively. The pressure waves in one working cycle and the flow field were displayed based on numerical simulation. Results shew that the energy was transfered by pressure waves and the vortexes generated during gradual opening and closing process led to a significant mixing between fluids and a distortion contact interface. Finally the effects of rotary speed and the gaps between ports and channels were investigated. With the increase of the inlet gap, the performance of the device reduced, while the outlet gap had a slight influence on performance. Besides, there was an optimal rotary speed for a fixed geometrical arrangement.

scholarly journals Transient Formation of Super-Explosives under High Pressure for Fast Ignition

2008 ◽  
Vol 63 (1-2) ◽  
pp. 35-41 ◽  
Author(s):  
Friedwardt Winterberg
Keyword(s):  
High Pressure ◽  
Energy Levels ◽  
Strong Shock ◽  
Dense Matter ◽  
Fast Ignition ◽  
Molecular Configuration ◽  
Exploding Wire ◽  
X Ray ◽  
Wire Arrays ◽  
Thermonuclear Target

Dense matter, if put under high pressure, can undergo a transformation from an atomic to a molecular configuration, where the electron orbits go into lower energy levels. If the rise in pressure is very sudden, for example by a strong shock wave, the electrons change their orbits rapidly under the emission of photons, which for more than 100 Mbar can reach keV energies. With the opacity of dense matter going in proportion to the density, the photons can be efficiently released from the surface of the compressed matter by a rarefaction wave. The so produced X-ray photons can be used for the fast ignition of a thermonuclear target.The proposed mechanism may be also responsible for the large keV X-ray bursts observed in exploding wire arrays, which can not be explained by conversion of kinetic into thermal energy.

The Port Width and Position Determination for Pressure-Exchange Ejector

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Wenjing Zhao ◽  
Dapeng Hu ◽  
Peiqi Liu ◽  
Yuqiang Dai ◽  
Jiupeng Zou ◽  
...  
Keyword(s):  
High Pressure ◽  
Performance Optimization ◽  
Pressure Ratio ◽  
Low Pressure ◽  
Operating Conditions ◽  
Maximum Deviation ◽  
Dimensionless Time ◽  
Pressure Flow ◽  
Outlet Pressure ◽  
Pressure Exchange

A pressure-exchange ejector transferring energy by compression and expansion waves has the potential for higher efficiency. The width and position of each port are essential in pressure-exchange ejector design. A dimensionless time τ expressing both port widths and the positions of port ends was introduced. A prototype was designed and the experimental system was set up. Many sets of experiment with different geometrical arrangements were conducted. The results suggest that the efficiency greatly changes with the geometrical arrangements. The efficiency is about 60% at proper port widths and positions, while at improper geometrical arrangements, the efficiency is much lower and the maximum deviation may reach about 20%. The proper dimensionless port widths and positions at different operating conditions are obtained. For a fixed overall pressure ratio, the widths of the high pressure flow inlet and middle pressure flow outlet increase as the outlet pressure increases and the low pressure flow inlet width is reduced with a larger outlet pressure. The middle pressure flow outlet (MO) opening end remains constant at different outlet pressures. The positions of the high pressure flow inlet (HI) closed end and the low pressure flow inlet (LI) open end increase with the elevation of outlet pressure, however, the distance between the HI closing end and the LI opening end is constant. The port widths and positions have a significant influence on the performance of the pressure-exchange ejector. The dimensionless data obtained are very valuable for pressure-exchange ejector design and performance optimization.

A Performance Autopsy of Three Centrifugal Compressors for a Small Gas Turbine

2010 ◽  
Author(s):  
Colin Rodgers ◽  
Dan Brown
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Radial Flow ◽  
Pressure Ratio ◽  
Test Results ◽  
Design Features ◽  
Centrifugal Compressors ◽  
High Pressure Ratio ◽  
Flow Type ◽  
The One

Three 140mm tip diameter centrifugal compressors were designed and tested to determine the one exhibiting the best performance most suitable for eventual application to a small 60KW radial flow type gas turbine. The design features, and stage test results of these three moderately high pressure ratio impellers are presented, together with a comparison of their respective test and CFD computed performance maps.

The Influence of Upstream Flow Angle Variation on Intermediate Turbine Duct

2014 ◽  
Vol 670-671 ◽  
pp. 705-708
Author(s):  
Yang Wang
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
Flow Condition ◽  
Quantitative Result ◽  
Complex Flow ◽  
High Pressure Turbine ◽  
Angle Variation ◽  
Flow Angle ◽  
Intermediate Turbine Duct ◽  
Upstream Flow

Intermediate turbine duct represent the flow path between the high pressure and low pressure turbine. Caused by the complex flow mechanism, the outlet flow condition of the high pressure turbine is easily changed. Since the upstream flow condition from the high pressure turbine has a significant effect on the internal flow field of intermediate turbine duct, the study in the upstream condition is of high value. Through numerical simulation, the influence of upstream flow angle variation on intermediate turbine duct is observed. It is found that the main influence of the flow angle variation is near the hub side of the duct, and the quantitative result shows that a larger flow angle has a positive effect on the flow field and can reduce loss.

Experimental Investigation of the Time-Averaged Flow in an Intermediate Turbine Duct

2008 ◽  
Author(s):  
Lars-Uno Axelsson ◽  
T. Gunnar Johansson
Keyword(s):  
Experimental Investigation ◽  
High Pressure ◽  
Low Pressure ◽  
Jet Engines ◽  
Mean Flow ◽  
Complex Flow ◽  
Turbofan Engines ◽  
Intermediate Turbine Duct ◽  
Static Pressure Distribution ◽  
Complex Flow Structure

Intermediate turbine ducts are used in modern multi-spool jet engines to connect the high pressure turbine with the low-pressure turbine. The trend towards turbofan engines with larger by-pass ratios requires the radial off-set between the high-pressure and low-pressure turbines to increase with a corresponding increase in radial off-set for the intermediate turbine ducts. Other improvements of the ducts is to make them shorter and more diffusing but this strive towards more aggressive design increases the risk for separation. This paper deals with an experimental investigation of the time-averaged mean flow field and turbulence development in an aggressive intermediate turbine duct (downstream a rotating turbine stage) using a 5-hole probe and 2-component hot-wire anemometry. In addition the duct endwall static pressure distribution is discussed. The investigation revealed the complex flow structure development within the duct, where co-rotating vortices emanating from the break-up of the tip gap shear-layer dominates the flow pattern.

Numerical Investigation of Non-Axisymmetric Endwalls in a High Pressure Axial Flow Turbine

2015 ◽  
Author(s):  
Zhenzhe Na ◽  
Bo Liu
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
Incidence Angle ◽  
Axial Flow ◽  
Field Calculation ◽  
Complex Flow ◽  
Flow Angle ◽  
Optimization System ◽  
Flow Loss ◽  
Stage Performance

In this paper, an optimization system was applied to design the non-axisymmetric endwalls for the stator of a high pressure axial flow turbine. This optimization system combines the endwall parameterization, 3D Navier-Stokes flow field calculation and genetic algorithm based on artificial neural network, which has the advantages of flexible geometry representation and automatic design of the optimal non-axisymmetric endwalls. And, the 3D steady flow field calculation was carried out to analyze the detailed behavior of complex flow structures pre and post optimization and to examine the influences of the optimized endwalls on the stage performance as well. The results of investigation show that the optimized non-axisymmetric endwalls can significantly decrease the flow loss in the stator, but also affect other aerodynamic parameters at the stator exit, especially the flow angle, and then the flow loss at the rotor exit caused by both the passage vortex in the rotor passage and the tip leakage vortex were increased by changing the incidence angle of the rotor due to the non-axisymmetric endwalls. Finally, the stage performance of the HP turbine is not improved as expected.

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