scholarly journals The Eulerian–Lagrangian Approach for the Numerical Investigation of an Acoustic Field Generated by a High-Speed Gas-Droplet Flow

Fluids ◽  
2021 ◽  
Vol 6 (8) ◽  
pp. 274
Author(s):  
Valeriia G. Melnikova ◽  
Andrey S. Epikhin ◽  
Matvey V. Kraposhin
Keyword(s):  
Numerical Investigation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
High Speed ◽  
Acoustic Noise ◽  
Hybrid Approach ◽  
Lagrangian Approach ◽  
Acoustic Properties ◽  
Lagrangian Model

This paper presents the Eulerian–Lagrangian approach for numerical modeling of high-speed gas-droplet flows and aeroacoustics. The proposed hybrid approach is implemented using the OpenFOAM library and two different methods. The first method is based on a hybrid convective terms approximation method employing a Kurganov–Tadmor and PIMPLE scheme. The second method employs the regularized or quasi-gas dynamic equations. The Lagrangian part of the flow description uses the OpenFOAM cloud model. Within this model, the injected droplets are simulated as packages (parcels) of particles with constant mass and diameter within each parcel. According to this model, parcels moving in the gas flow could undergo deceleration, heating, evaporation, and breakup due to hydrodynamic instabilities. The far-field acoustic noise is predicted using Ffowcs Williams and Hawking’s analogy. The Lagrangian model is verified using the cases with droplet evaporation and motion. Numerical investigation of water microjet injection into the hot ideally expanded jet allowed studying acoustic properties and flow structures, which emerged due to the interaction of gas and liquid. Simulation results showed that water injection with a mass flow rate equal to 13% of the gas jet mass flow rate reduced the noise by approximately 2 dB. This result was in good coincidence with the experimental observations, where maximum noise reduction was about 1.6 dB.

Condensation-Induced Water Hammer in Horizontal Refrigerant Pipe With Warm Gas Entry

2003 ◽  
Author(s):  
C. Samuel Martin
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
High Speed ◽  
Fast Response ◽  
Ammonia Gas ◽  
Pressure Transducers ◽  
High Speed Data Acquisition ◽  
High Speed Data ◽  
Liquid Depth

Careful experiments have been conducted for the purpose of investigating the phenomenon of condensation-induced waterhammer in an ammonia refrigeration system. To initiate a waterhammer event warm ammonia gas was introduced over static subcooled ammonia liquid placed in a horizontal 146.3 mm diameter carbon steel pipe 6.0 m in length. By means of fast response piezoelectric pressure transducers and a high speed data acquisition system rapid dynamic pressures were recorded whenever a shock event occurred. The occurrence of condensation-induced waterhammer depended upon three major variables; namely, (1) initial liquid depth, (2) liquid temperature, and (3) mass flow rate of warm gas. For given liquid depth and temperature, once the warm gas threshold conditions were exceeded shocks occurred with greater magnitude as the mass flow rate of gas input was increased. With adequate subcooling condensation-induced waterhammer occurred for initial liquid depths ranging from 25% to 95% of internal pipe diameter. The threshold mass flow rate of warm gas necessary to initiate waterhammer was greater as the initial liquid was lowered.

Experimental Investigation of Oil Flowrate in a Hermetic Reciprocating Compressor

2014 ◽  
Author(s):  
Sibel Tas ◽  
Sertac Cadirci ◽  
Hasan Gunes ◽  
Kemal Sarioglu ◽  
Husnu Kerpicci
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rotational Speed ◽  
High Speed ◽  
Operating Conditions ◽  
Lubricating Oil ◽  
Reciprocating Compressor ◽  
Oil Flow ◽  
Oil Flow Visualization

The aim of this experimental study is to investigate the mass flow rate of the lubricating oil in a hermetic reciprocating compressor. Essential parameters affecting the performance of the lubrication are the rotational speed of the crankshaft, the viscosity of the oil, the operating temperature and the submersion depth of the crankshaft. An experimental setup was built as to measure the oil mass flow rate with respect to the oil temperature variation during different operating conditions. The influence of the governing parameters such as the rotational speed, temperature (viscosity) and the submersion depth on the mass flow rate from crankshaft outlet are studied in detail. In addition, the oil flow visualization from the upper hole of the crankshaft is performed using a high-speed camera in order to observe the effectiveness of the lubrication of the various parts of the compressor. This study reveals that with increasing rotational speed, the submersion depth of the crankshaft and with decreasing viscosity of the lubricant, the mass flow rate from the crankshaft increases.

Unstart phenomena induced by mass addition and heat release in a model scramjet

2016 ◽  
Vol 797 ◽  
pp. 604-629 ◽  
Author(s):  
S. Im ◽  
D. Baccarella ◽  
B. McGann ◽  
Q. Liu ◽  
L. Wermer ◽  
...  
Keyword(s):  
Heat Release ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
High Speed ◽  
Free Stream ◽  
Mass Loading ◽  
High Enthalpy ◽  
Hypersonic Wind Tunnel ◽  
Flow Features

The unstart phenomena in a model scramjet with a free stream Mach number of 4.5 were investigated at an arc-heated hypersonic wind tunnel. High-speed schlieren imaging and high resonance frequency pressure measurements were used to capture the flow features during the unstart process. Three unstart conditions were tested: (i) a low-enthalpy free stream with mass loading, (ii) a high-enthalpy free stream with mass loading and (iii) a high-enthalpy free stream with mass loading and heat release. It was revealed that the unstart threshold and the time from the onset to the completion of unstart depended strongly on the mass loading rate and the heat exchange. The negative heat addition (cooling) significantly increased the threshold of mass flow rate triggering unstart. The decrement of the mass flow rate threshold for unstart was observed in the presence of heat release by combustion. The observed transient and quasi-steady behaviours of the unstart shockwave system and the jet motion were similar in all of the test conditions. On the other hand, at the lip of inlet model, the unstart shockwave under the cold free stream condition exhibited a relatively steady behaviour while severe oscillatory flow motions of the jet and the unstart shockwave were observed in the combustion-driven unstart process. The different unstarted flow behaviours between the three flow conditions were explained using a simplified one-dimensional flow choking analysis and use of the Korkegi criterion.

scholarly journals Quasi 3D Nacelle Design to Simulate Crosswind Flows: Merits and Challenges

2019 ◽  
Vol 4 (3) ◽  
pp. 25 ◽  
Author(s):  
Alex Yeung ◽  
Nagabhushana Rao Vadlamani ◽  
Tom Hynes ◽  
Sumit Sarvankar
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
High Speed ◽  
Computational Modelling ◽  
Flow Characteristics ◽  
Attached Flow ◽  
Set Up ◽  
Engine Nacelle ◽  
Shape Changes

This paper studies the computational modelling of the flow separation over the engine nacelle lips under the off-design condition of significant crosswind. A numerical framework is set up to reproduce the general flow characteristics under crosswinds with increasing engine mass flow rate, which include: low-speed separation, attached flow and high speed shock-induced separation. A quasi-3D (Q3D) duct extraction method from the full 3D (F3D) simulations has been developed. Results obtained from the Q3D simulations are shown to largely reproduce the trends observed (isentropic Mach number variations and high-speed separation behaviour) in the 3D intake, substantially reducing the simulation time by a factor of 50. The agreement between the F3D and Q3D simulations is encouraging when the flow either fully attached or with modest levels of separation but degrades when the flow fully detaches. Results are shown to deviate beyond this limit since the captured streamtube shape (and hence the corresponding Q3D duct shape) changes with the mass flow rate. Interestingly, the drooped intake investigated in the current study is prone to earlier separation under crosswinds when compared to an axisymmetric intake. Implications of these results on the industrial nacelle lip design are also discussed.

scholarly journals Flow Investigation in a Small High Speed Impeller Passage Using Laser Anemometry

1990 ◽  
Author(s):  
N. A. Ahmed ◽  
R. L. Elder
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
High Speed ◽  
Three Dimensional ◽  
Experimental Results ◽  
Centrifugal Impeller ◽  
Laser Velocimetry ◽  
Laser Anemometry ◽  
Flow Investigation

The paper describes experimental results obtained using laser velocimetry in a small high speed centrifugal impeller. The formation of wakes and the effect of varying speed and mass flow rate on the flow within the impeller passages are presented. In addition, an indication of the three dimensional nature of the impeller flow is discussed (the three dimensional results being obtained using a novel Doppler anemometer).

scholarly journals Numerical investigation on the cooling performance of a novel jet cooler design for a supercritical CO2 turbine rotor shaft cooling

2021 ◽  
Vol 22 ◽  
pp. 51
Author(s):  
Jun Li ◽  
Hal Gurgenci ◽  
Jishun Li ◽  
Zhiqiang Guan ◽  
Lun Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Investigation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Transfer Performance ◽  
Negative Impact ◽  
Dominant Factor ◽  
Transfer Performance ◽  
Fluid Density

Numerical investigation was carried out to study the heat transfer performance for a high-speed rotating cylindrical surface subjected to single row array round jets impingement, under a very small gap spacing. Various parameters that affect heat transfer, such as the fluid density, flow velocity and Nusselt number distributions of the radius clearance were studied based on varied nozzle to target surface spacing H and mass flow rate. It has been found that the fluid density was a dominant factor and the velocity was the secondary factor for the gas jet heat transfer performances. The overall heat transfer was improved with a reduction in the number of nozzles, for given inlet mass flow rate boundary conditions. The decrease of H/di (di, nozzle diameter) may have positive or negative effects on the heat transfer performance from the impingement surface. Reducing the radius gap H, for a certainty, increases the average density of the fluid in the clearance, which is desirable in applications that enhance heat transfer performance. But when the radius gap (H) is small enough, increasing di may have a negative impact on heat transfer.

Numerical Investigation on the Flow Characteristics in a Cover-Plate Pre-Swirl System

2021 ◽  
Author(s):  
Menghua Jian ◽  
Xuesen Yang ◽  
Wei Dong
Keyword(s):  
Reynolds Number ◽  
Numerical Investigation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Circumferential Velocity ◽  
Cover Plate ◽  
Temperature Reduction

Abstract This paper presents a numerical investigation on the flow characteristics in a cover-plate pre-swirl system. The Reynolds-averaged Navier-Stokes equations, coupled with the standard k-ε turbulent model, are adopted and solved. With the inlet total pressure and total temperature being constant, the influences of the temperature reduction and flow resistance by changing pressure ratios and rotational Reynolds numbers were conducted. Flow features in the pre-swirl nozzle, pre-swirl cavity, receiver hole and cover-plate cavity were summarized. The results obtained in this study indicate that the pressure ratio and rotational Reynolds number have a significant influence on the vortex structure of the pre-swirl system. As the air is accelerated by the pre-swirl nozzle, the difference of circumferential velocity between the air and the rotational domain would be reduced, and the static temperature of the air would be decreased. The pressure drop in the pre-swirl system mainly occurs in the pre-swirl nozzle and the pre-swirl cavity. In addition, with the increase of the pressure ratio, the air mass flow rate and the circumferential velocity of the air out of the nozzle increased, thereby leading to an increment in temperature reduction. Moreover, with the increasing of the rotational Reynolds number, the dimensionless mass flow rate and temperature reduction of the pre-swirl system, which are mainly determined by the flow incidence angle of cooling air at the receiver hole, will first increase to a maximum and then decrease.

scholarly journals Atomization of Gel Fuels with Solid Particle Addition Utilizing an Air Atomizing Nozzle

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2959
Author(s):  
Yunlei Xiao ◽  
Zhixun Xia ◽  
Liya Huang ◽  
Likun Ma ◽  
Dali Yang
Keyword(s):  
Mass Flow Rate ◽  
Solid Particle ◽  
Mass Flow ◽  
Flow Rate ◽  
High Speed ◽  
Droplet Diameter ◽  
Aluminum Particle ◽  
Solid Particles ◽  
Particle Content ◽  
Boron Particle

Microscopic high-speed imaging is used to experimentally measure the velocity and size of droplets of gelled RP-1 based fuels with a solid particle additive. The gels are atomized using an air atomizing nozzle. The droplet diameter and velocity at a fixed position 20 cm from the nozzle on the centerline of the spray are measured at air mass flow rates of 1.5, 3 and 5 g/s. A parametric study is conducted to study the effect of gas mass flow rate, boron particle content, and species of the solid particle on the droplet characteristics. The results indicate that the droplet size decreases with the increasing of gas mass flow rate and boron particle content. Gel fuels with an aluminum particle are observed to produce smaller droplets at a low gas mass flow rate than that with a boron particle. The implication of these observations is that the atomization processes for gelled fuels with an additive of solid particles is controlled by the velocity difference between the gas and the droplets.

Sign in / Sign up

Export Citation Format

Share Document