Experimental investigations into the effects of string cavitation on diesel nozzle internal flow and near field spray dynamics under different injection control strategies

Gas Carry-Under (GCU) is one of the undesirable phenomena that exists in the GLCC©1 even within the Operational Envelope (OPEN) for liquid carry-over. Few studies that are available on GLCC© GCU have been carried out when the GLCC© is operated in a metering loop configuration characterized by recombined outlets. In such configurations the gas and the liquid outlets of the GLCC are recombined downstream which acts as passive level control. However, studies have shown that the GLCC© OPEN increases significantly when active control strategies are employed. There has not been a systematic study aimed at analyzing the effect of control on the GCU in the GLCC. This study compares the previously published GLCC GCU swirling flow mechanism under recombination outlet configuration with data taken under the separated outlet configuration (control configuration). Experimental investigations for GCU are conducted in a state-of-the-art test facility for air-water and air-oil flow incorporating pressure and level control configurations. The experiments are carried out using a 3″ diameter GLCC© equipped with 3 sequential trap sections to measure simultaneously the Gas Volume Fraction (GVF) and gas evolution in the lower part of the GLCC. Also, gas trap sections are installed in the liquid leg of the GLCC© to measure simultaneously the overall GCU. The liquid level was controlled at 6″ below the GLCC© inlet for all experiments using various control strategies. Tangential wall jet impingement is the cause for entrainment of gas, thereby leading to GCU. 3 different flow mechanisms have been identified in the lower part of the GLCC and have significant effect on the GCU. Viscosity and surface tension are observed to affect the GCU. The extensive acquired data shed light on the complex flow behavior in the lower part of the GLCC© and its effect on the GCU of the GLCC©.

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An experimental study of underexpanded sonic, coaxial, swirl jets

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/095440604322786974 ◽

2004 ◽

Vol 218 (1) ◽

pp. 93-103 ◽

Cited By ~ 4

Author(s):

K-H Lee ◽

T Setoguchi ◽

S Matsuo ◽

H-D Kim

Keyword(s):

Static Pressure ◽

Near Field ◽

Flow Structures ◽

Experimental Investigations ◽

Pressure Measurements ◽

Annular Nozzle ◽

Free Jets ◽

Underexpanded Jets ◽

Secondary Stream ◽

The Impact

The present study addresses experimental investigations of the near-field flow structures of an underexpanded sonic, dual, coaxial, swirl jet. The swirl stream is discharged from the secondary annular nozzle and the primary inner nozzle provides the underexpanded free jets. The interactions between the secondary swirl and primary underexpanded jets are quantified by a fine pitot impact and static pressure measurements and are visualized using a shadowgraph optical method. The pressure ratios of the secondary swirl and primary underexpanded jets are varied below 7.0. Experiments are conducted to investigate the effects of the secondary swirl stream on the primary underexpanded jets, compared with the secondary stream of no swirl. The results show that the presence of an annular swirl stream causes the Mach disc to move further downstream, with an increased diameter, and remarkably reduces the fluctuations of the impact pressures in the underexpanded sonic dual coaxial jet, compared with the case of the secondary annular stream with no swirl.

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On the nature of the microwave field emerging from a composite pupil

Modern Physics Letters B ◽

10.1142/s0217984920502474 ◽

2020 ◽

Vol 34 (24) ◽

pp. 2050247

Author(s):

Ilaria Cacciari ◽

Daniela Mugnai ◽

Anedio Ranfagni

Keyword(s):

Wave Propagation ◽

Stochastic Model ◽

Radio Frequency ◽

Delay Time ◽

Microwave Field ◽

Near Field ◽

Phase Variation ◽

Experimental Investigations ◽

Frequency Signal ◽

Made In

Further experimental investigations in the microwave field emerging from a composite pupil are reported in order to determine the nature of the wave propagation. The experiments consisted of delay-time measurements as a function of the distance of the detector from the pupil under test, as well as of the phase variation of a radio-frequency signal at 35 MHz that modulated the same microwave carrier at 9.33 GHz. In addition, measurements employing an admittance comparator were made in order to determine the character of the propagation impedance. All results obtained confirmed superluminal behavior in the near field, up to a distance of about 40 cm. These results were then interpreted within the framework of a stochastic model.

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Study on Influence of Nozzle Structure on Flow in Diesel Nozzle Orifice

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.246-247.127 ◽

2012 ◽

Vol 246-247 ◽

pp. 127-130

Author(s):

Bing Li ◽

Xue Song Hu ◽

Xiao Feng Cao ◽

Gui Qi Jia ◽

Fang Xi Xie ◽

...

Keyword(s):

Flow Characteristics ◽

Internal Flow ◽

Key Factors ◽

Complex Flow ◽

Two Phase ◽

Nozzle Orifice ◽

Fuel Flow ◽

Flow Features ◽

Diesel Nozzle ◽

Nozzle Hole

The fuel flow characteristics in diesel nozzle orifice are key factors to the atomization of fuel near the nozzle orifice. In the paper, two-phase flow model is used to simulate the complex flow features in nozzle orifice, and to study the influences of the relative position of nozzles orifice axis and nozzle axis, and inclination angle of nozzle hole on the internal flow feature.

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PREDICTION OF NOISE GENERATED BY A ROUND NOZZLE JET FLOW USING COMPUTATIONAL AEROACOUSTICS

Journal of Computational Acoustics ◽

10.1142/s0218396x11004365 ◽

2011 ◽

Vol 19 (03) ◽

pp. 291-316 ◽

Cited By ~ 23

Author(s):

ALI UZUN ◽

M. YOUSUFF HUSSAINI

Keyword(s):

Flow Field ◽

Near Field ◽

Internal Flow ◽

Jet Flow ◽

Computational Aeroacoustics ◽

Far Field ◽

Free Jet ◽

Grid Points ◽

Field Noise ◽

Inflow Conditions

This paper demonstrates an application of computational aeroacoustics to the prediction of noise generated by a round nozzle jet flow. In this study, the nozzle internal flow and the free jet flow outside are computed simultaneously by a high-order accurate, multi-block, large-eddy simulation (LES) code with overset grid capability. To simulate the jet flow field and its radiated noise, we solve the governing equations on approximately 370 million grid points using high-fidelity numerical schemes developed for computational aeroacoustics. Projection of the near-field noise to the far-field is accomplished by coupling the LES data with the Ffowcs Williams–Hawkings method. The main emphasis of these simulations is to compute the jet flow in sufficient detail to accurately capture the physical processes that lead to noise generation. Two separate simulations are performed using turbulent and laminar inflow conditions at the jet nozzle inlet. Simulation results are compared with the corresponding experimental measurements. Results show that nozzle inflow conditions have an influence on the jet flow field and far-field noise.

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Diesel Engine Fuel Injection Control Using a Model-Guided Extremum-Seeking Method

Volume 1: Adaptive and Intelligent Systems Control; Advances in Control Design Methods; Advances in Non-Linear and Optimal Control; Advances in Robotics; Advances in Wind Energy Systems; Aerospace Applications; Aerospace Power Optimization; Assistive Robotics; Automotive 2: Hybrid Electric Vehicles; Automotive 3: Internal Combustion Engines; Automotive Engine Control; Battery Management; Bio Engineering Applications; Biomed and Neural Systems; Connected Vehicles; Control of Robotic Systems ◽

10.1115/dscc2015-9967 ◽

2015 ◽

Author(s):

Prasad Divekar ◽

Qingyuan Tan ◽

Xiang Chen ◽

Ming Zheng ◽

Ying Tan

Keyword(s):

Diesel Engine ◽

Fuel Injection ◽

Online Optimization ◽

Extremum Seeking ◽

External Boundary ◽

Experimental Investigations ◽

Control Input ◽

Engine Fuel ◽

Engine Model ◽

Injection Control

Diesel engine fuel injection control is presented as a feedback based online optimization problem. Extremum seeking (ES) approach is used to address the online optimization formulation. The cost function is synthesized from extensive experimental investigations such that the indicated thermal efficiency of the engine is maximized while minimizing the NOx emissions under external boundary conditions. Knowledge of the physical combustion and emission formation process based on a pre-calibrated non-linear engine model output is used to determine the ES initial control input to minimize the seeking time. The control is demonstrated on a hardware-in-the-loop engine simulator bench.

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Local, Near-Field Mixing Augmentation Using Square Coaxial Jets

Volume 1: Turbo Expo 2004 ◽

10.1115/gt2004-53985 ◽

2004 ◽

Author(s):

Samuel Bonnafous ◽

Victor Piffaut ◽

Wai-Ho Choy ◽

Dimitris E. Nikitopoulos

Keyword(s):

Near Field ◽

Internal Flow ◽

Spreading Rate ◽

Central Plane ◽

Mean Velocity ◽

Mixing Rates ◽

Spreading Rates ◽

Diagonal Plane ◽

Axis Switching ◽

First Time

Results from un-forced experiments in flows ensuing from circular and equivalent square coaxial nozzles with parallel sides are presented in this paper. The nozzles are contoured and are designed so that the hydraulic diameters of the internal flow passages are identical for both geometries. The flow experiments were conducted at a co-flow-jet Reynolds number of Re = 16,000 and inner-to-outer jet nominal velocity ratios of λ = 0, 0.5, 1.5. Axis switching, a phenomenon readily observed in single non-axisymmetric nozzles, is shown for the first time to occur in the square coaxial nozzles as well. Comparisons of the mixing regions of the flows from both geometries are made to examine mixing advantages when using square nozzle configurations. Comparisons of stream wise mean velocity fields measured on a center plane parallel to the square nozzle sides, on a diagonal plane of the square nozzle and the center plane of the corresponding circular nozzle, are presented and discussed. Axis switching is shown to be evident in the near-field shear regions for all velocity ratios, resulting in considerable mixing advantages. The spreading rates (and therefore mixing rates) of the outer mixing region of the square nozzles clearly exceed the spreading rate observed in the circular case on the central plane. Axis switching and improved mixing is also observed in the inner mixing region of the square nozzle. This work is relevant to coaxial nozzles for gas turbine combustor applications, although the study has been carried out in a scaled up geometry with respect to this application.

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Control of piezoelectric friction dampers in smart base-isolated structures using self-tuning and adaptive fuzzy proportional–derivative controllers

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x16667561 ◽

2016 ◽

Vol 28 (10) ◽

pp. 1287-1302 ◽

Cited By ~ 14

Author(s):

Abbas-Ali Zamani ◽

Saeed Tavakoli ◽

Sadegh Etedali

Keyword(s):

Control Strategies ◽

Near Field ◽

The Self ◽

Feedback Signal ◽

Far Field ◽

Friction Dampers ◽

Adaptive Fuzzy ◽

Self Tuning ◽

Base Displacement ◽

Proportional Derivative Controller

To adjust the contact force of piezoelectric friction dampers for a benchmark base-isolated structure, a self-tuning fuzzy proportional–derivative controller and an adaptive fuzzy proportional–derivative controller are developed. Considering three candidate signals, namely, the isolation displacement, isolation velocity, and roof acceleration, the best feedback signal for the self-tuning fuzzy proportional–derivative controller is selected based on the Pareto-optimal front. The performance of the self-tuning fuzzy proportional–derivative controller during both near-field and far-field earthquakes is enhanced using an adaptive fuzzy proportional–derivative controller, in which the output gain of the self-tuning fuzzy proportional–derivative controller is adaptively tuned according to the kind of entering earthquake. The control objective is to reduce the isolation system deformations without significant increase in superstructure accelerations during far-field and near-field earthquake excitations. Membership functions and fuzzy control rules are simultaneously tuned using a multi-objective cuckoo search algorithm. Considering 14 real-data earthquakes, simulation results show that the proposed controllers perform better than other reported control strategies in terms of simultaneous reduction of the maximum base displacement and superstructure accelerations. Also, they provide acceptable responses in terms of the inter-story drifts, root mean squared of base displacement, and the floor acceleration. Opposite to other reported control strategies, piezoelectric friction dampers controlled by the self-tuning fuzzy proportional–derivative controller and adaptive fuzzy proportional–derivative controller never enter the saturation area.

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