Numerical and Experimental Studies of Gas Pulsations in the Suction Manifold of a Multicylinder Automotive Compressor

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Jeong-Il Park ◽  
Nasir Bilal ◽  
Douglas E. Adams ◽  
Yoshinobu Ichikawa ◽  
Jacob Bayyouk
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Experimental Studies ◽  
Beam Equation ◽  
Discharge Process ◽  
Simulation Code ◽  
Calculated Mass ◽  
Linear Differential ◽  
Gas Pulsations

This study predicts gas pulsations in the suction manifold of a multicylinder automotive air-conditioning compressor using a comprehensive simulation model of a reciprocating compressor. On the basis of the first law of thermodynamics and a simplified fourth-order Bernoulli-Euler linear differential beam equation for suction valves, the pressure in a cylinder and resultant pressure pulsation in the suction manifold are predicted. The mass flow rate through the valve is estimated assuming one-dimensional compressible flow through an orifice. All of the equations are then solved together in a sequence to obtain the pressure in the cylinder, valve response, and the mass flow rate. A complicated suction manifold geometry is modeled as a simplified cylindrical annular cavity to study gas pulsations in a multicylinder compressor, but the discharge process has not been considered in this study. Using the calculated mass flow rate, pressure pulsations in a simplified cylindrical annular cavity with an area change to consider “mode splitting” are predicted based on the characteristic cylinder method. It is shown that the simulation code can be a useful tool for predicting gas pulsations in the suction manifold of a multicylinder automotive compressor.

Gas Pulsation Reductions in a Multicylinder Compressor Suction Manifold Using Valve-to-Valve Mass Flow Rate Phase Shifts

2007 ◽  
Vol 129 (4) ◽  
pp. 406-416 ◽  
Author(s):  
Jeong-Il Park ◽  
Nasir Bilal ◽  
Douglas E. Adams
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Beam Equation ◽  
Pressure Pulsations ◽  
Flow Rates ◽  
Calculated Mass ◽  
Mass Flow Rates ◽  
Linear Differential ◽  
Cylinder Method

This paper investigates the pressure pulsations caused by each mass flow rate through the suction valves and ports of a multicylinder compressor in order to attribute high-pressure pulsation responses to certain valves. By staggering the valve configurations appropriately, it is shown that the level of gas pulsations in the suction manifold of a multicylinder automotive compressor can be reduced. First, the equation for a compression cycle, a Bernoulli-Euler linear differential beam equation for the suction valves, and the piston kinematics are considered in order to calculate the mass flow rates through the compressor suction valves. The pressure pulsations in the suction manifold are then predicted based on the characteristic cylinder method using the calculated mass flow rates. In order to investigate the effects of each mass flow rate, the characteristics and phases of the mass flow rates through the suction valves are changed by modifying the clearance volume.

scholarly journals Numerical and Experimental Study of Microchannel Performance on Flow Maldistribution

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 323 ◽  
Author(s):  
Jojomon Joseph ◽  
Danish Rehman ◽  
Michel Delanaye ◽  
Gian Luca Morini ◽  
Rabia Nacereddine ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Experimental Studies ◽  
Wire Mesh ◽  
Pressure Losses ◽  
Macro Scale ◽  
Flow Maldistribution

Miniaturized heat exchangers are well known for their superior heat transfer capabilities in comparison to macro-scale devices. While in standard microchannel systems the improved performance is provided by miniaturized distances and very small hydraulic diameters, another approach can also be followed, namely, the generation of local turbulences. Localized turbulence enhances the heat exchanger performance in any channel or tube, but also includes an increased pressure loss. Shifting the critical Reynolds number to a lower value by introducing perturbators controls pressure losses and improves thermal efficiency to a considerable extent. The objective of this paper is to investigate in detail collector performance based on reduced-order modelling and validate the numerical model based on experimental observations of flow maldistribution and pressure losses. Two different types of perturbators, Wire-net and S-shape, were analyzed. For the former, a metallic wire mesh was inserted in the flow passages (hot and cold gas flow) to ensure stiffness and enhance microchannel efficiency. The wire-net perturbators were replaced using an S-shaped perturbator model for a comparative study in the second case mentioned above. An optimum mass flow rate could be found when the thermal efficiency reaches a maximum. Investigation of collectors with different microchannel configurations (s-shaped, wire-net and plane channels) showed that mass flow rate deviation decreases with an increase in microchannel resistance. The recirculation zones in the cylindrical collectors also changed the maldistribution pattern. From experiments, it could be observed that microchannels with S-shaped perturbators shifted the onset of turbulent transition to lower Reynolds number values. Experimental studies on pressure losses showed that the pressure losses obtained from numerical studies were in good agreement with the experiments (<4%).

Investigation of the Mass Flow Sources in a Multi-Cylinder Compressor Using Frequency Response of Pressure Pulsations in the Suction Manifold

2003 ◽  
Author(s):  
Jeong-Il Park ◽  
Douglas E. Adams ◽  
Yoshinobu Ichikawa ◽  
Jacob Bayyouk
Keyword(s):  
Frequency Response ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Wave Theory ◽  
Inhomogeneous Equation ◽  
Pressure Pulsations ◽  
Pole Parameter ◽  
Gas Pulsations ◽  
Thermodynamic Equations

Linear acoustic plane wave theory and a four pole parameter formulation are used to derive and solve the governing inhomogeneous equation for the forced pressure response in the simplified manifold model. The equations for estimating gas pressure pulsations in the annular cavity connected to an anechoic inlet pipe are presented. Complicated interactions between multiple cylinder valve ports in the suction manifold produce unexpected changes in the frequency response conditions for changes in the operating speed, and hence, the flow rate characteristics through the valves. From the addition of the delayed time for opening valve in the mass flow rate profiles and the comparison of the gas pulsations from experiment with those from simulation, the maximum strokes of the piston and the delayed times for opening valve can be estimated without solving the valve dynamic and thermodynamic equations. By applying the mass flow rate sinks at each valve as identified, the correlation between analytical and experimental results is shown to be much better than if the idealized, kinematically obtained source functions are used instead.

Optimization of the process of reproducing units of mass and volume of liquid in a stream, mass and volumetric flow rates of liquid for calibration units with weighing devices

2020 ◽  
pp. 60-64
Author(s):  
R. A. Korneev ◽  
A. R. Tukhvatullin ◽  
V. A. Fafurin ◽  
R. R. Nigmatullin ◽  
A. V. Shchelchkov
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Storage Tank ◽  
Experimental Studies ◽  
Working Fluid ◽  
Time Interval ◽  
Flow Rates ◽  
Wide Range ◽  
Flow Switch

The publication presents an experimental method for estimating the minimum time interval for filling a storage tank with a working fluid with a fixed geometry of the nozzle of the flow switch of the calibration plant when playing units of mass and volume of fluid in the flow, mass and volumetric flow rates of the fluid. Experimental studies were performed in a wide range of mass flow rate 11,10–83,26 kg/s (40–300 t/h) with repeated static weighing of the working fluid. The flow switch is made with a fixed geometry of the flow part of the nozzle exit, which is typical for a large number of calibration units in use in our country with weighing devices. The graphical dependences of the mass flow rate on the time of filling the storage capacity obtained from the research results are the basis for optimizing the process of reproducing units of mass and volume of liquid in the flow, mass and volumetric flow rates of the liquid for calibration plants with weighing devices. These graphical dependencies made it possible to formulate recommendations on the reasonable choice of the minimum interval for filling the storage tank with working fluid in the studied range of mass flow rate. Optimization has been tested and can be extended to calibration units with weighing devices from various manufacturers with individual design and operating parameters.

scholarly journals Performance Trends For Aerospikes & Supersonic Nozzles With Center-Bodies

2021 ◽  
Author(s):  
Bassel El-Dahr
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Specific Impulse ◽  
Working Fluid ◽  
Base Case ◽  
Conical Nozzle ◽  
Ansys Fluent ◽  
Supersonic Nozzles ◽  
Calculated Mass

The aim of this report is to examine performance trends for Aerospikes and Supersonic nozzles with center – bodies. The initial case that was tested is a convergent – divergent conical nozzle with a geometry and inlet flow conditions obtained from a NASA technical note. The technical note mentions that air was used as the working fluid for the nozzle. This case served as the base case for comparison with the performance of later nozzle designs. Nozzle flow for all the cases that were tested was simulated using ANSYS Fluent, for ambient conditions at 20km standard atmosphere. The convergent – divergent conical nozzle has the following calculated performance parameters using results from ANSYS Fluent: mass flow rate of 9.660 kg/s, axial Thrust of 10,583.5 N, and a specific impulse of 111.7s. All of the Supersonic nozzles with center – bodies have calculated specific impulse values lower than 111.7s by 0.4 – 1.6s, for approximately the same calculated mass flow rates as the base case. Adding a center – body to the original conical nozzle, was simply detrimental to performance. With regards to the Aerospike nozzles, 18 of them were tested. Aerospike 18 has the highest calculated specific impulse, at 115.3s for a calculated mass flow rate of 9.671kg/s. Aerospike 13 came in second at 114.6s, for a calculated mass flow rate of 9.676 kg/s. Several of the Aerospike designs did not out-perform the base case in terms of specific impulse. For those Aerospikes, the convergent – divergent section had a significantly lower thrust than the base case and the center – body was not able to over-compensate for the lower thrust. This report also looks at trends in thrust contribution by the convergent – divergent sections and center – bodies of Aerospikes at different nozzle geometries. The working fluid for all the cases tested in ANSYS Fluent including the base case, is air at a ratio of specific heats equal to 1.4.

scholarly journals Performance Simulation of a 5 kW hall Thruster

2021 ◽  
Vol 8 ◽  
Author(s):  
L. Yang ◽  
P. Y. Wang ◽  
T. Wang
Keyword(s):  
Magnetic Field ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Oscillation Amplitude ◽  
Discharge Voltage ◽  
Hall Thruster ◽  
Total Efficiency ◽  
Discharge Process ◽  
Steady State Oscillation

Hall thruster is a kind of plasma optics device, which is used mainly in space propulsion. To simulate the discharge process of plasma and the performance of a 5 kW hall thruster, a two-dimensional PIC-MCC model in the R-Z plane is built. In the model, the anomalous diffusion of the electrons including Bohm diffusion and near-wall conduction is modeled. The Bohm diffusion is modeled by using a Brownian motion instead of the Bohm collision method and the near-wall conduction is modeled by a secondary electron emission model. In addition to the elastic, excitation, and ionization collisions between electrons and neutral atoms, the Coulomb collisions are included. The plasma discharge process including the transient oscillation and steady state oscillation is well reproduced. First, the influence of the discharge voltage and magnetic field on the steady state oscillation is simulated. The oscillation amplitude increases as the discharge voltage gets larger at first, and then decreases. While the oscillation amplitude decreases as the magnetic field gets stronger at first, and then increases. Later, the influence of the discharge voltage and mass flow rate on the performance of the thruster is simulated. When the mass flow rate is constant, the total efficiency initially increases with the discharge voltage, reaches the maximum at 600 V, and then declined. When the discharge voltage is constant, the total efficiency increases as the mass flow rate rises from 10 to 15 mg/s. Finally, a comparison between simulated and experimental performance reveals that the largest deviation is within 15%, thereby indirectly validating the accuracy of the model.

scholarly journals Performance Trends For Aerospikes & Supersonic Nozzles With Center-Bodies

2021 ◽  
Author(s):  
Bassel El-Dahr
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Specific Impulse ◽  
Working Fluid ◽  
Base Case ◽  
Conical Nozzle ◽  
Ansys Fluent ◽  
Supersonic Nozzles ◽  
Calculated Mass

The aim of this report is to examine performance trends for Aerospikes and Supersonic nozzles with center – bodies. The initial case that was tested is a convergent – divergent conical nozzle with a geometry and inlet flow conditions obtained from a NASA technical note. The technical note mentions that air was used as the working fluid for the nozzle. This case served as the base case for comparison with the performance of later nozzle designs. Nozzle flow for all the cases that were tested was simulated using ANSYS Fluent, for ambient conditions at 20km standard atmosphere. The convergent – divergent conical nozzle has the following calculated performance parameters using results from ANSYS Fluent: mass flow rate of 9.660 kg/s, axial Thrust of 10,583.5 N, and a specific impulse of 111.7s. All of the Supersonic nozzles with center – bodies have calculated specific impulse values lower than 111.7s by 0.4 – 1.6s, for approximately the same calculated mass flow rates as the base case. Adding a center – body to the original conical nozzle, was simply detrimental to performance. With regards to the Aerospike nozzles, 18 of them were tested. Aerospike 18 has the highest calculated specific impulse, at 115.3s for a calculated mass flow rate of 9.671kg/s. Aerospike 13 came in second at 114.6s, for a calculated mass flow rate of 9.676 kg/s. Several of the Aerospike designs did not out-perform the base case in terms of specific impulse. For those Aerospikes, the convergent – divergent section had a significantly lower thrust than the base case and the center – body was not able to over-compensate for the lower thrust. This report also looks at trends in thrust contribution by the convergent – divergent sections and center – bodies of Aerospikes at different nozzle geometries. The working fluid for all the cases tested in ANSYS Fluent including the base case, is air at a ratio of specific heats equal to 1.4.

Parametric Study of a Thermosyphon Loop Pressure Drop Model

2004 ◽  
Author(s):  
Jinsong Zhang ◽  
Jason Hugenroth ◽  
Issam Mudawar ◽  
Timothy S. Fisher
Keyword(s):  
Heat Flux ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Flow Boiling ◽  
Current System ◽  
Experimental Studies ◽  
Two Phase ◽  
Flow Area ◽  
Cross Sectional

A closed loop two-phase thermosyphon has been modeled based on earlier experimental and numerical studies by Mukherjee and Mudawar [1, 2]. Unlike conventional thermosyphons in which the heat dissipating device is submerged in a pool of liquid coolant, the current system uses a flow boiling arrangement. The advantage is that for a given boiling surface area, the critical heat flux (CHF) can be increased. Parametric studies with respect to adiabatic section flow areas, boiler section flow area, and system height were performed. The maximum practical heat flux that is attainable is predicted, as well as other flow parameters such as mass flow rate, flow velocities and fluid quality existing the boiler. Performance enhancements relative to the original system, may be possible by introducing a divergent cross sectional area in the boiler section that increases the system mass flow rate. It can also, however, reduce the flow velocity in certain sections of the boiler, tending to reduce the boiler CHF. Experimental studies are recommended to determine if an actual improvement can be realized.

scholarly journals Experimental Study of Photovoltaic Thermal-Thermoelectric (PVT-TE) Air Collector

2018 ◽  
Vol 9 (3) ◽  
pp. 1390
Author(s):  
Nurul Syakirah Nazri ◽  
Ahmad Fudholi ◽  
Mohd Hafidz Ruslan ◽  
Kamaruzzaman Sopian
Keyword(s):  
Experimental Study ◽  
Energy Efficiency ◽  
Mass Flow Rate ◽  
Hybrid System ◽  
Mass Flow ◽  
Flow Rate ◽  
Experimental Studies ◽  
Plate Temperature ◽  
System Effect ◽  
Photovoltaic Panel

In this study, an experimental study has been conducted to determine the performance of the photovoltaic thermal- thermoelectric air collector (PVT-TE) hybrid system. Hybrid system consists of photovoltaic panel (PV) and thermoelectric modules (TEs) that can improve the energy efficiency of the system. The results of output temperature (To) and plate temperature (Tp) obtained from the experiment have been used to determine the performance of this hybrid system. Effect of mass flow rate and radiation intensity is also being investigated. Experimental studies were carried out at 0.02 kg/s and 0.09 kg/s which represent minimum and maximum of mass flow rate, and radiation intensities in the range of 268-922 W/m<sup>2</sup>.

The standard unit mass flow rate of gas-liquid mixtures

2020 ◽  
pp. 13-16
Author(s):  
V.N. Petrov ◽  
◽  
V.F. Sopin ◽  
L.A. Akhmetzyanova ◽  
Ya.S. Petrova ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Liquid Mixtures ◽  
Unit Mass ◽  
Standard Unit
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