scholarly journals Development of Hybrid Airlift-Jet Pump with Its Performance Analysis

2018 ◽  
Vol 8 (9) ◽  
pp. 1413 ◽  
Author(s):  
Dan Yao ◽  
Kwongi Lee ◽  
Minho Ha ◽  
Cheolung Cheong ◽  
Inhiug Lee
Keyword(s):  
Boundary Conditions ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Jet Pump ◽  
Two Phase

A new pump, called the hybrid airlift-jet pump, is developed by reinforcing the advantages and minimizing the demerits of airlift and jet pumps. First, a basic design of the hybrid airlift-jet pump is schematically presented. Subsequently, its performance characteristics are numerically investigated by varying the operating conditions of the airlift and jet parts in the hybrid pump. The compressible unsteady Reynolds-averaged Navier-Stokes equations, combined with the homogeneous mixture model for multiphase flow, are used as the governing equations for the two-phase flow in the hybrid pump. The pressure-based methods combined with the Pressure-Implicit with Splitting of Operators (PISO) algorithm are used as the computational fluid dynamics techniques. The validity of the present numerical methods is confirmed by comparing the predicted mass flow rate with the measured ones. In total, 18 simulation cases that are designed to represent the various operating conditions of the hybrid pump are investigated: eight of these cases belong to the operating conditions of only the jet part with different air and water inlet boundary conditions, and the remaining ten cases belong to the operating conditions of both the airlift and jet parts with different air and water inlet boundary conditions. The mass flow rate and the efficiency are compared for each case. For further investigation into the detailed flow characteristics, the pressure and velocity distributions of the mixture in a primary pipe are compared. Furthermore, a periodic fluctuation of the water flow in the mass flow rate is found and analyzed. Our results show that the performance of the jet or airlift pump can be enhanced by combining the operating principles of two pumps into the hybrid airlift-jet pump, newly proposed in the present study.

scholarly journals Performance investigation of a volute porous tongue of a turbocharger turbine

2020 ◽  
Vol 40 (1) ◽  
pp. 59-66
Author(s):  
Abderrahmane Chachoua ◽  
Mohamed Kamal Hamidou ◽  
Mohammed Hamel
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Turbines ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Recirculation Flow ◽  
Recirculating Flow ◽  
Show Evidence ◽  
The Right

The design for better performance of the spiral housing volute used commonly in radial and mixed inflow gas turbines is of prime importance as it affects the machine stage at both design and off design conditions. The tongue of the scroll divides the flow into two streams, and represents a severe source of disturbances, in terms of thermodynamic parameter uniformity, maximum kinetic energy, the right angle of attack to the rotor and minimum losses. Besides, the volute suffers an undesirable effect due to the recirculating mass flow rate in near bottom vicinity of the tongue. The present project is an attempt to design a tongue fitted with cylindrical holes traversing normal to the stream wise direction, where on account of the large pressure difference between the top and the bottom sides of the tongue will force the recirculating flow to go through the rotor inlet. This possibility with its limitations has not yet been explored. A numerical simulation is performed which might provide our suitable objectives. To achieve this goal the ANSYS code is used to build the geometry, generate the mesh, and to simulate the flow by solving numerically the averaged Navier Stokes equations. Apparently, the numerical results show evidence of favorable impact in using porous tongue. The realization of a contact between the main and recirculation flow by drilled holes on the tongue surface leads to a flow field uniformity, a reduction in the magnitude of the loss coefficient, and a 20 % reduction in the recirculating mass flow rate.

EXPERIMENTAL AND CFD INVESTIGATION OF R410A DISTRIBUTORS FOR AIR CONDITIONER

2014 ◽  
Vol 22 (02) ◽  
pp. 1440002 ◽  
Author(s):  
QING HAN ◽  
CHI ZHANG ◽  
JIANGPING CHEN
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Present Model ◽  
Cfd Simulation ◽  
Operating Conditions ◽  
Maximum Deviation ◽  
Two Phase ◽  
Performance Reduction

In order to obtain a higher heat transfer coefficient of refrigerant flow, the diameter of tubes tends to be smaller and smaller, which leads to large pressure drop of the refrigerant flow. Therefore, multiple numbers of parallel refrigerant passages are employed by using distributors. It is very important to distribute the two-phase refrigerant evenly into each tube, otherwise the thermal performance is significantly deteriorated. The performance reduction by flow mal-distribution could be as large as 20–25%. The goal of this paper is to investigate the influence of different configurations to the performance of refrigerant distributors by experiments and computational fluid dynamic code. The effects of mass flow rate and quality of distributor inlet on the characteristics were also quantitatively considered. In this study, an experiment test rig was built to measure the mass flow rate and quality of four circuits after using distributors under different conditions respectively. Refrigerant R410A was used as working fluids. Three classic types (jet, cyclone and reservoir) of distributors with four paths were manufactured and tested under relevant operating conditions. The inlet temperature was 4°C, mass flow rate range was 50–100 kg/h and the quality range was 0.1–0.3. Experimental results show that the maximum deviation of mass flow rate for jet, cyclone and reservoir type is 13.0%, 21.6% and 10.9%, respectively; the maximum deviation of quality was 0.08, 0.10 and 0.05, respectively. In addition, the standard deviation of mass flow rate and quality over four paths were selected to evaluate the performance of different type distributors. The results show that the performance of jet and reservoir are better than cyclone. The flow behavior of two-phase refrigerant such as phase distribution and separation phenomena was studied by Computational Fluid Dynamics (CFD). The flow pattern of inlet for R410A was investigated and used in the present model. The results in the present model show good and reasonable approximation with experimental data which validate the CFD simulation. CFD simulation analysis elucidates the mechanics which shows how the configuration and operation conditions affect the refrigerant distribution.

scholarly journals Differential Throttling and Fluidic Thrust Vectoring in a Linear Aerospike

2021 ◽  
Vol 6 (2) ◽  
pp. 8
Author(s):  
Michele Ferlauto ◽  
Andrea Ferrero ◽  
Matteo Marsicovetere ◽  
Roberto Marsilio
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Combustion Chambers ◽  
Thrust Vectoring ◽  
Fluidic Thrust Vectoring

Aerospike nozzles represent an interesting solution for Single-Stage-To-Orbit or clustered launchers owing to their self-adapting capability, which can lead to better performance compared to classical nozzles. Furthermore, they can provide thrust vectoring in several ways. A simple solution consists of applying differential throttling when multiple combustion chambers are used. An alternative solution is represented by fluidic thrust vectoring, which requires the injection of a secondary flow from a slot. In this work, the flow field in a linear aerospike nozzle was investigated numerically and both differential throttling and fluidic thrust vectoring were studied. The flow field was predicted by solving the Reynolds-averaged Navier–Stokes equations. The thrust vectoring performance was evaluated in terms of side force generation and axial force reduction. The effectiveness of fluidic thrust vectoring was investigated by changing the mass flow rate of secondary flow and injection location. The results show that the response of the system can be non-monotone with respect to the mass flow rate of the secondary injection. In contrast, differential throttling provides a linear behaviour but it can only be applied to configurations with multiple combustion chambers. Finally, the effects of different plug truncation levels are discussed.

Steady-State and Unsteady Simulations of a High Velocity Jet Into a Venturi Shaped Pipe

2014 ◽  
Author(s):  
Bernhard Semlitsch ◽  
Estelle Laurendeau ◽  
Mihai Mihăescu
Keyword(s):  
Steady State ◽  
Flow Field ◽  
Large Eddy Simulation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Navier Stokes ◽  
Jet Pump ◽  
Eddy Simulation ◽  
Large Eddy

A jet pump consists mainly of a convergent-divergent Venturi shaped duct where a primary stream is applied with the role of entraining a secondary jet. Due to their simple and reliable concept, jet pumps are used in miscellaneous applications. Performance optimization of a jet pump has to be performed for various operation conditions. Thus, numerically robust and cheap models, able to predict accurately the performance parameters of such devices are necessary. Reynolds Averaged Navier-Stokes based formulations are computationally efficient to predict the performance of a jet pump. However, these simulations rely on turbulence closure coefficients, which need to be validated with experimental observations. Large Eddy Simulation solves the most energetic structures in the flow field and it can be used to capture the flow dynamics. On the experimental side, confined geometries challenge the investigation capabilities to capture the flow field accurately and in all the details. The flow field in the jet pump is investigated using Large Eddy Simulation approach and a steady state Reynolds Averaged Navier-Stokes formulation. The flow field solutions obtained with the two numerical tools are compared. A reasonable agreement for the velocity and pressure contours could be achieved. However, the turbulence kinetic energy distribution and the entrained mass flow rate are predicted to be distinct. The difference in entrained mass flow rate leads to differences in jet pump efficiency estimation.

Thermal Characterization of Interlayer Microfluidic Cooling of Three-Dimensional Integrated Circuits With Nonuniform Heat Flux

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Yoon Jo Kim ◽  
Yogendra K. Joshi ◽  
Andrei G. Fedorov ◽  
Young-Joon Lee ◽  
Sung-Kyu Lim
Keyword(s):  
Integrated Circuits ◽  
Mass Flow Rate ◽  
Thermal Management ◽  
Mass Flow ◽  
Flow Rate ◽  
Single Phase ◽  
Hot Spot ◽  
Three Dimensional ◽  
Two Phase ◽  
Two Phase Cooling

It is now widely recognized that the three-dimensional (3D) system integration is a key enabling technology to achieve the performance needs of future microprocessor integrated circuits (ICs). To provide modular thermal management in 3D-stacked ICs, the interlayer microfluidic cooling scheme is adopted and analyzed in this study focusing on a single cooling layer performance. The effects of cooling mode (single-phase versus phase-change) and stack/layer geometry on thermal management performance are quantitatively analyzed, and implications on the through-silicon-via scaling and electrical interconnect congestion are discussed. Also, the thermal and hydraulic performance of several two-phase refrigerants is discussed in comparison with single-phase cooling. The results show that the large internal pressure and the pumping pressure drop are significant limiting factors, along with significant mass flow rate maldistribution due to the presence of hot-spots. Nevertheless, two-phase cooling using R123 and R245ca refrigerants yields superior performance to single-phase cooling for the hot-spot fluxes approaching ∼300 W/cm2. In general, a hybrid cooling scheme with a dedicated approach to the hot-spot thermal management should greatly improve the two-phase cooling system performance and reliability by enabling a cooling-load-matched thermal design and by suppressing the mass flow rate maldistribution within the cooling layer.

scholarly journals Experimental Investigation and Modeling of Inertance Tubes

2005 ◽  
Vol 127 (5) ◽  
pp. 1029-1037 ◽  
Author(s):  
L. O. Schunk ◽  
G. F. Nellis ◽  
J. M. Pfotenhauer
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Acoustic Power ◽  
Operating Conditions ◽  
Thermodynamic Efficiency ◽  
Pulse Tube ◽  
Design Charts ◽  
Wide Range ◽  
Pulse Tube Refrigerators

Growing interest in larger scale pulse tubes has focused attention on optimizing their thermodynamic efficiency. For Stirling-type pulse tubes, the performance is governed by the phase difference between the pressure and mass flow, a characteristic that can be conveniently adjusted through the use of inertance tubes. In this paper we present a model in which the inertance tube is divided into a large number of increments; each increment is represented by a resistance, compliance, and inertance. This model can include local variations along the inertance tube and is capable of predicting pressure, mass flow rate, and the phase between these quantities at any location in the inertance tube as well as in the attached reservoir. The model is verified through careful comparison with those quantities that can be easily and reliably measured; these include the pressure variations along the length of the inertance tube and the mass flow rate into the reservoir. These experimental quantities are shown to be in good agreement with the model’s predictions over a wide range of operating conditions. Design charts are subsequently generated using the model and are presented for various operating conditions in order to facilitate the design of inertance tubes for pulse tube refrigerators. These design charts enable the pulse tube designer to select an inertance tube geometry that achieves a desired phase shift for a given level of acoustic power.

Research on Two-Phase Flow Instability in Evaporator of Refrigeration System

2010 ◽  
Author(s):  
Nan Liang ◽  
Changqing Tian ◽  
Shuangquan Shao
Keyword(s):  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Density Wave ◽  
Phase Flow ◽  
Constant Mass ◽  
Refrigeration System ◽  
Two Phase

As one kind of fluid machinery related to the two-phase flow, the refrigeration system encounters more problems of instability. It is essential to ensure the stability of the refrigeration systems for the operation and efficiency. This paper presents the experimental investigation on the static and dynamic instability in an evaporator of refrigeration system. The static instability experiments showed that the oscillatory period and swing of the mixture-vapor transition point by observation with a camera through the transparent quartz glass tube at the outlet of the evaporator. The pressure drop versus mass flow rate curves of refrigerant two phase flow in the evaporator were obtained with a negative slope region in addition to two positive slope regions, thus making the flow rate a multi-valued function of the pressure drop. For dynamic instabilities in the evaporation process, three types of oscillations (density wave type, pressure drop type and thermal type) were observed at different mass flow rates and heat fluxes, which can be represented in the pressure drop versus mass flow rate curves. For the dynamic instabilities, density wave oscillations happen when the heat flux is high with the constant mass flow rate. Thermal oscillations happen when the heat flux is correspondingly low with constant mass flow rate. Though the refrigeration system do not have special tank, the accumulator and receiver provide enough compressible volume to induce the pressure drop oscillations. The representation and characteristic of each oscillation type were also analyzed in the paper.

Experimental and Numerical Investigations on the Aerodynamic Performance of the Three-Stage Turbine With Consideration of the Leakage Flow Effect

2016 ◽  
Author(s):  
Yang Chen ◽  
Jun Li ◽  
Chaoyang Tian ◽  
Gangyun Zhong ◽  
Xiaoping Fan ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rotor Blade ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Navier Stokes ◽  
Leakage Flow ◽  
Leakage Flows ◽  
Wheel Disk

The aerodynamic performance of three-stage turbine with different types of leakage flows was experimentally and numerically studied in this paper. The leakage flows of three-stage turbine included the shroud seal leakage flow between the rotor blade tip and case, the diaphragm seal leakage flow between the stator blade diaphragm and shaft, as well as the shaft packing leakage flow and the gap leakage flow between the rotor blade curved fir-tree root and wheel disk. The total aerodynamic performance of three-stage turbine including leakage flows was firstly experimentally measured. The detailed flow field and aerodynamic performance were also numerically investigated using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) and S-A turbulence model. The numerical mass flow rate and efficiency showed well agreement with experimental data. The effects of leakage flows between the fir-tree root and the wheel disk were studied. All leakage mass flow fractions, including the mass flow rate in each hole for all sets of root gaps were given for comparison. The effect of leakage flow on the aerodynamic performance of three-stage was illustrated and discussed.

scholarly journals Analytical and Experimental Investigation of a Plate Fin Heat Exchanger at Cryogenics Temperature

2021 ◽  
Vol 39 (4) ◽  
pp. 1225-1235
Author(s):  
Ajay K. Gupta ◽  
Manoj Kumar ◽  
Ranjit K. Sahoo ◽  
Sunil K. Sarangi
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Cryogenic Temperature ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Compact Size

Plate-fin heat exchangers provide a broad range of applications in many cryogenic industries for liquefaction and separation of gasses because of their excellent technical advantages such as high effectiveness, compact size, etc. Correlations are available for the design of a plate-fin heat exchanger, but experimental investigations are few at cryogenic temperature. In the present study, a cryogenic heat exchanger test setup has been designed and fabricated to investigate the performance of plate-fin heat exchanger at cryogenic temperature. Major parameters (Colburn factor, Friction factor, etc.) that affect the performance of plate-fin heat exchangers are provided concisely. The effect of mass flow rate and inlet temperature on the effectiveness and pressure drop of the heat exchanger are investigated. It is observed that with an increase in mass flow rate effectiveness and pressure drop increases. The present setup emphasis the systematic procedure to perform the experiment based on cryogenic operating conditions and represent its uncertainties level.

Reduced-Order Modelling of Rotating Stall

2020 ◽  
Author(s):  
Dominik Schlüter ◽  
Robert P. Grewe ◽  
Fabian Wartzek ◽  
Alexander Liefke ◽  
Jan Werner ◽  
...  
Keyword(s):  
Single Cell ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rotational Speed ◽  
Stability Limit ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Transonic Compressor ◽  
Experimental Findings

Abstract Rotating stall is a non-axisymmetric disturbance in axial compressors arising at operating conditions beyond the stability limit of a stage. Although well-known, its driving mechanisms determining the number of stall cells and their rotational speed are still marginally understood. Numerical studies applying full-wheel 3D unsteady RANS calculations require weeks per operating point. This paper quantifies the capability of a more feasible quasi-2D approach to reproduce 3D rotating stall and related sensitivities. The first part of the paper deals with the validation of a numerical baseline the simplified model is compared to in detail. Therefore, 3D computations of a state-of-the-art transonic compressor are conducted. At steady conditions the single-passage RANS CFD matches the experimental results within an error of 1% in total pressure ratio and mass flow rate. At stalled conditions, the full-wheel URANS computation shows the same spiketype disturbance as the experiment. However, the CFD underpredicts the stalling point by approximately 7% in mass flow rate. In deep stall, the computational model correctly forecasts a single-cell rotating stall. The stall cell differs by approximately 21% in rotational speed and 18% in circumferential size from the experimental findings. As the 3D model reflects the compressor behaviour sufficiently accurate, it is considered valid for physical investigations. In the second part of the paper, the validated baseline is reduced in radial direction to a quasi-2D domain only resembling the compressor tip area. Four model variations regarding span-wise location and extent are numerically investigated. As the most promising model matches the 3D flow conditions in the rotor tip region, it correctly yields a single-cell rotating stall. The cell differs by only 7% in circumferential size from the 3D results. Due to the impeded radial migration in the quasi-2D slice, however, the cell exhibits an increased axial extent. It is assumed, that the axial expansion into the adjacent rows causes the difference in cell speed by approximately 24%. Further validation of the reduced model against experimental findings reveals, that it correctly reflects the sensitivity of circumferential cell size to flow coefficient and individual cell speed to compressor shaft speed. As the approach reduced the wall clock time by 92%, it can be used to increase the physical understanding of rotating stall at much lower costs.

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