scholarly journals Swirl–nozzle interaction experiment: quasi-steady model-based analysis

2021 ◽  
Vol 62 (8) ◽  
Author(s):  
Lionel Hirschberg ◽  
Friedrich Bake ◽  
Karsten Knobloch ◽  
Angelo Rudolphi ◽  
Sebastian Kruck ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Acoustic Pressure ◽  
Quantitative Information ◽  
Acoustic Response ◽  
Flow Measurements ◽  
Flow Rate Change ◽  
Interaction Experiment ◽  
Swirl Stabilized Combustion

AbstractMeasurements of sound due to swirl–nozzle interaction are presented. In the experiment a swirl structure was generated by means of unsteady tangential injection into a steady swirl-free flow upstream from a choked convergent–divergent nozzle. Ingestion of swirl by the choked nozzle caused a mass-flow rate change, which resulted in a downstream-measured acoustic response. The downstream acoustic pressure was found to remain negative as long as the swirl is maintained and reflections from the open downstream pipe termination do not interfere. The amplitude of this initial acoustic response was found to be proportional to the square of the tangential mass-flow rate used to generate swirl. When the tangential injection valve was closed, the mass-flow rate through the nozzle increased, resulting in an increase of the downstream acoustic pressure. This increase in signal was compared to the prediction of an empirical quasi-steady model, constructed from steady-state flow measurements. As the opening time of the valve was varied, the signal due to swirl evacuation showed an initial overshoot with respect to quasi-steady behavior, after which it gradually decayed to quasi-steady behavior for tangential injection times long compared to the convection time in the pipe upstream of the nozzle. This demonstrates that the acoustic signal can be used to obtain quantitative information concerning the time dependence of the swirl in the system. This could be useful for understanding the dynamics of flow in engines with swirl-stabilized combustion. Graphic abstract

DI-CNG Injector Characterization at Small Energizing Times by Means of Numerical Simulation

2012 ◽  
Author(s):  
Mirko Baratta ◽  
Andrea E. Catania ◽  
Nicola Rapetto ◽  
Alois Fuerhapter ◽  
Matthias Gerlich ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Research Effort ◽  
Flow Behavior ◽  
Direct Injection ◽  
Time History ◽  
Operating Conditions ◽  
Flow Measurements ◽  
Injection Duration

In the last few years, a significant research effort has been made for developing and enhancing Direct Injection (DI) for compressed natural gas (CNG) engines. Several research projects have been promoted by the European Community (EC) in this field with the objective of finding new solutions for the automotive market and also of encouraging a fruitful knowledge exchange among car manufacturers, suppliers and technical universities. This paper concerns part of the research activity that has been carried out by the Politecnico di Torino, AVL List GmbH and Siemens AG within the EC VII Framework Program (FP) InGAS Collaborative Project (CP), aimed at optimizing the control phase of a new injector for CNG direct injection, paying specific attention to its behavior at small injected-fuel amounts, i.e., small energizing times. The CNG injector which was developed within the research project proved to be suitable to be used in a DI SI engine, featuring a pent-roof combustion chamber head and a bowl in piston, with reference to both homogeneous and stratified charge formation. Fuel flow measurements made by AVL on the four-cylinder engine revealed a good linearity between injection duration and fuel mass-flow rate for injection durations above a reference value. In order to improve the injector characterization at short injection durations, an experimental and numerical activity was designed. More specifically, a multidimensional CFD model of the actual injector geometry was built by Politecnico di Torino, and purposely-designed simulation cases were carried out, in which the needle-lift time-history was defined on the basis of experimental measurements made by Siemens. The numerical model was validated on the basis of experimental data concerning the total injected-fuel amount under different conditions. Then, the model was applied in order to evaluate the dynamic flow characteristic by taking also the inner geometry of the injector valve group into account, so as to establish a correlation to the needle lift measurements done by Siemens for injector characterization. In the paper this dynamic behavior of the injector is analyzed, under actual operating conditions, and its impact on the nozzle injection capability is discussed. The simulation results did not show significant oscillations of the stagnation pressure upstream of the nozzle throat section, and thus the resultant mass-flow rate profile is almost proportional to the needle-lift one. As a consequence, in order to characterize the injector flow behavior in the nonlinear region (short injection duration), the measurement of needle lift is sufficient.

Effect of Condenser Temperature and Speed on one A/C System

2011 ◽  
Vol 314-316 ◽  
pp. 686-690
Author(s):  
Cheng Jun Pan ◽  
Yi Da Tang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Air Conditioning ◽  
Systems Design ◽  
Test System ◽  
Coefficient Of Performance ◽  
Two Phase ◽  
Flow Measurements ◽  
Air Conditioning System

This study describes the results on the performance of one vehicle air conditioning system. The coefficient of performance, evaporator cooling capacity, compressor power consumption, total mass flow rate, vapor mass flow rate, liquid mass flow rate and oil in circulation, pressures and temperatures of refrigerant at every component (inlets and outlets) are measured and analyzed with the variation of the outside temperatures at the evaporator and condenser, the speed of the compressor, refrigerant charge and oil charge. The systematical experimental results obtained from this real-size test system depict the relations between the above parameters in a vehicle air conditioning system, which constitute a useful source for vehicle air conditioning systems design and analysis. The vapor quality (two-phase flow) measurements realized in this work provide an extremely important tool for diagnosing the system performances.

scholarly journals Modelling Bubble Lifetime of Thin Film Surfactants Solution on Fuel Spillage

2021 ◽  
pp. 20-33
Author(s):  
Shitakha Felistus ◽  
Kimathi George ◽  
Songa Caroline
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rate Change ◽  
Eastern Africa ◽  
Maximum Lifetime ◽  
Catholic University ◽  
Fluid Properties ◽  
Flow Rate Change ◽  
The Stability

Aims / Objectives: To find the lifetime of the bubble by plotting the rate of mass flow rate change against time. Place and Duration of Study: Department of Mathematics and Applied Science, Catholic University of Eastern Africa, Nairobi, Kenya, between February 2020 and March 2021. Methodology: The maximum lifetime of the bubble is assumed to match the time when the mass flow rate change is zero. The study also assumes the velocity of flow rate and other fluid properties at the interface of fuel-surfactant constant other than Re. Re is varied from 0.01 to 100. Results: The graphical plots show that for Re ! 1, and Re " 1, the stability depends on diffusive viscosity and linearized convection, respectively. The simulation suggested that the bubble formed at the fuel-surfactant interface may have Re “ 1 and its lifetime is tb » 0.28. Conclusion: The lifetime of surfactant depends on Re while assuming other interface properties constant. Recommendation: Future studies in the area need to consider the effect of variation in temperature, velocity, and Reynolds number in determining the lifetime of a bubble in the thin foam of the surfactant-fuel interface.

Experimental Investigation on Swirl and Heat Transfer Within a Rotor-Stator Cavity

2016 ◽  
Author(s):  
Daniele Massini ◽  
Bruno Facchini ◽  
Mirko Micio ◽  
Riccardo Da Soghe
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Mass Flow Rate ◽  
Working Conditions ◽  
Mass Flow ◽  
Flow Rate ◽  
System Effect ◽  
Flow Measurements ◽  
Wide Range ◽  
Admission System

A rotating test rig, reproducing a rotor-stator cavity with an axial admission system, has been exploited for an experimental investigation on the internal flow field and its effect on heat transfer on the stator side. Working conditions were varied in a wide range of rotating velocities and superposed mass flow rates. 2D PIV flow measurements were performed in order to obtain a radial distribution of the tangential velocity, results were used to validate numerical simulations aimed at understanding the admission system effect on the swirl distribution. Heat transfer coefficient distribution along the stator disk has been evaluated performing a steady state technique exploiting Thermo-chromic Liquid Crystals (TLC). Tests have been performed varying the superposed mass flow rate up to reaching the condition of cavity completely sealed, further increase of the mass flow rate showed to reduce the effect of the rotation. Working conditions were set in order to investigate cases missing in open literature, however few tests performed in similarity with other researches provided comparable results.

Review and Analysis of Cross Flow Heat Exchanger Transient Modeling for Flow Rate and Temperature Variations

2015 ◽  
Vol 7 (4) ◽  
Author(s):  
Tianyi Gao ◽  
James Geer ◽  
Bahgat Sammakia
Keyword(s):  
Heat Exchanger ◽  
Mass Flow Rate ◽  
Transient Response ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Inlet Temperature ◽  
Flow Rate Change ◽  
Flow Heat

Heat exchangers are important facilities that are widely used in heating, ventilating, and air conditioning (HVAC) systems. For example, heat exchangers are the primary units used in the design of the heat transfer loops of cooling systems for data centers. The performance of a heat exchanger strongly influences the thermal performance of the entire cooling system. The prediction of transient phenomenon of heat exchangers is of increasing interest in many application areas. In this work, a dynamic thermal model for a cross flow heat exchanger is solved numerically in order to predict the transient response under step changes in the fluid mass flow rate and the fluid inlet temperature. Transient responses of both the primary and secondary fluid outlet temperatures are characterized under different scenarios, including fluid mass flow rate change and a combination of changes in the fluid inlet temperature and the mass flow rate. In the ε-NTU (number of transfer units) method, the minimum capacity, denoted by Cmin, is the smaller of Ch and Cc. Due to a mass flow rate change, Cmin may vary from one fluid to another fluid. The numerical procedure and transient response regarding the case of varying Cmin are investigated in detail in this study. A review and comparison of several journal articles related to the similar topic are performed. Several sets of data available in the literatures which are in error are studied and analyzed in detail.

Effect of Refrigerant Charge and Inlet Air Temperature on One A/C System

2011 ◽  
Vol 71-78 ◽  
pp. 2142-2146
Author(s):  
Cheng Jun Pan ◽  
Yi Da Tang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Air Conditioning ◽  
Systems Design ◽  
Test System ◽  
Coefficient Of Performance ◽  
Two Phase ◽  
Flow Measurements ◽  
Air Conditioning System

This study describes the results on the performance of one vehicle air conditioning system. The coefficient of performance, evaporator cooling capacity, compressor power consumption, total mass flow rate, vapor mass flow rate, liquid mass flow rate and oil in circulation, pressures and temperatures of refrigerant at every component (inlets and outlets) are measured and analyzed with the variation of the outside temperatures at the evaporator and condenser, the speed of the compressor, refrigerant charge and oil charge. The systematical experimental results obtained from this real-size test system depict the relations between the above parameters in a vehicle air conditioning system, which constitute a useful source for vehicle air conditioning systems design and analysis. The vapor quality (two-phase flow) measurements realized in this work provide an extremely important tool for diagnosing the system performances.

Experimental Study of a New Flow Conditioner on Disturbed Flow in Orifice Plate Metering

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
A. Ahmadi
Keyword(s):  
Experimental Study ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Discharge Coefficient ◽  
Swirling Flow ◽  
Reynolds Numbers ◽  
Experimental Results ◽  
Orifice Plate ◽  
Flow Measurements

The sensitivity to poor conditioned and swirling flow of flow measurements using an orifice plate are subjects of concern to flowmeter users and manufacturers. Measurements of mass flow rate under different conditions and different Reynolds numbers were used to establish a change in discharge coefficient relative to the standard one. The experimental results show that an optimally shaped flow conditioner could attenuate the effects of both swirl and asymmetrical flows. The optimization of the swirler flow conditioner is a main outcome of this work. So far the experimental results show that the cone swirler flow conditioner is the best one for swirling flow.

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
Sign in / Sign up

Export Citation Format

Share Document