Numerical investigation of mass flow rate effects on multiplicity of detonation waves within a H2/Air rotating detonation combustor

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.

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

Mechanics & Industry ◽

10.1051/meca/2021049 ◽

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.

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

10.1115/gt2021-59164 ◽

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.

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Numerical Investigation of Parameters Affecting the Thermal and Hydrodynamic Characteristics of Impinging Jets in Cross Flow

IIUM Engineering Journal ◽

10.31436/iiumej.v1i1.329 ◽

1970 ◽

Vol 1 (1) ◽

Author(s):

B. M. Suloiman ◽

B. A. Jubran

Keyword(s):

Numerical Investigation ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Velocity Ratio ◽

Cross Flow ◽

Impinging Jets ◽

Minor Effect ◽

Vortex Strength ◽

Effective Velocity

In this investigation the hydrodynamic and the thermal fields due to a single impinging jet in cross-flow have been investigated numerically, using a 2-D axisymmetric model in order to predict the ground vortex characteristics. The parameters investigated include the effective velocity ratio, the nozzle height, the nozzle pressure ratio, the intake location, the intake mass flow rate and the jet temperature ratio. It is interesting to note that even with the 2-D modeling limitations it was possible to capture most of the thermal and fluid field characteristics of the ground vortex. It was found that the temperature distribution in the flow field is greatly affected by the effective velocity, and the maximum penetration point of the ground vortex is equal to the hot gas penetration. The ground vortex strength increases slightly with increasing the intake mass flow rate but has a minor effect on the ground vortex geometry and on the penetration of the hot gases. The intake location has a significant effect on the ground vortex strength when it is located upstream of the ground vortex core. Key Words: Numerical investigation, Turbulence Models, Impinging jets, Cross-flow.

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