Influences of key parameters on flow features in the curved ducts with equal area

2021 ◽  
pp. 095440622110631
Author(s):  
Xiao-lin Sun ◽  
Shan Ma
Keyword(s):  
Test Data ◽  
Transonic Flow ◽  
Critical Mass ◽  
Flow Characteristics ◽  
Polar Coordinate System ◽  
Outer Diameter ◽  
Equal Area ◽  
Flow Features ◽  
Curved Section ◽  
Curved Ducts

Curved ducts are widely used in aircraft engines to improve some capability of aero-engines. Complex internal flow characteristics would be induced by the curvature in such components. In this study, the influence of parameters, including the arc angle α, the curvature radius R i, and the height H, on the local accelerating and transonic flow in the curved ducts with equal area were studied numerically and theoretically under different nozzle pressure ratios (NPRs). The range of the Re number based on the height of the duct and the velocity at the inlet was [Formula: see text] ∼ [Formula: see text]. The shear stress transport κ-ω turbulent model was proved by the test data to suitably simulate the flow field in curved ducts because it could accurately predict the flow separations under adverse pressure gradients. The uncertainty of the pressure scan value to obtain the test data was ±0.05%. Numerical results showed that the effect of α on the flow characteristics of the curved ducts is little. The maximum Ma number in the curved section reduces with the increase of R i, and that grows with the increase of H. The range of the maximum Ma number was 1.20∼1.80. The critical NPRs, which decided the special flow features, were found in the curved ducts. The critical NPR rises with the increase of R i; however, the effect of H on the critical NPR is irregular due to the flow separations located near the lower wall induced by the large adverse pressure gradient. The theoretical results based on the small perturbation theory of transonic flow in the polar coordinate system proved that the distribution of sonic line was just dependent on the inner diameter R1, the outer diameter R2, and the arc angle θmax of the curved section. The critical mass flow and the critical NPR2 are only related to R1 and R2.

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

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.

Numerical Simulation of Cavitating Flow Over 2D Hydrofoil Using OpenFOAM Adapted for Debian Operating System With LXDE Based in Kernel GNU/Linux

2014 ◽  
Author(s):  
Victor Hugo Hidalgo Diaz ◽  
XianWu Luo ◽  
RenFang Huang ◽  
Edgar Cando
Keyword(s):  
Operating System ◽  
Open Source ◽  
Open Source Software ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Cavitating Flow ◽  
Cavitating Flows ◽  
Ansys Fluent ◽  
Flow Features ◽  
Free Open Source

Though commercial CFD codes are widely used in flow analysis, but there are free/open source programs which have been applying for computational fluid dynamics. An open source software makes it possible to customize the solver according to the flow features. In the present paper, cavitating flows over 2D NACA66 hydrofoil were simulated based on open source software, where SALOME is used for mesh generation, OpenFOAM for flow solution under Debian GNU/Linux operating system. The results show the simulated cavitating flow characteristics such as cavity revolution, vortex shedding, cavitation induced pressure vibrations, etc. are validated by experiments and results obtained from proprietary software as Ansys Fluent. Thus, the proposed numerical methods based on open source platform are suitable for flow simulations, even for depicting the complicated physics of cavitation.

scholarly journals A Two-Dimensional Study of Transonic Flow Characteristics in Steam Control Valve for Power Plant

2010 ◽  
Vol 3 (1) ◽  
pp. 58-66
Author(s):  
Koichi Yonezawa ◽  
Yoshinori Terachi ◽  
Toru Nakajima ◽  
Yoshinobu Tsujimoto ◽  
Kenichi Tezuka ◽  
...  
Keyword(s):  
Power Plant ◽  
Transonic Flow ◽  
Flow Characteristics ◽  
Control Valve ◽  
Two Dimensional

Design and Development of an Improved Air Distributor for a Large Coal-Fired Fluidised Bed Combustor

2008 ◽  
Author(s):  
John Ward ◽  
Roy Garwood ◽  
Randall Bowen ◽  
Maurice Fisher ◽  
David Gent
Keyword(s):  
Distribution System ◽  
Pipe Wall ◽  
Flow Characteristics ◽  
Thin Layers ◽  
Outer Diameter ◽  
Fluidised Bed ◽  
Operating Life ◽  
Cross Sectional ◽  
Pipe Length ◽  
Pipe System

The air distribution system in a fluidised bed combustor is usually required to provide a reasonably uniform distribution of combustion air over the cross-sectional area of the entire bed. Various designs of distributor have been employed and one of the simplest and cheapest constructions is the so-called sparge pipe system, in which an array of horizontal pipes is fitted near the base of the bed. Combustion air is then supplied to one end of each pipe and enters the bed through a series of downward facing holes positioned along the pipe length. This paper describes the re-design and subsequent modification of an existing sparge pipe distributor for a large coal fired fluidised bed combustor which produced hot exhaust gases for drying of pressed sugar beet pulp. The air flow out of the holes in the existing pipes varied by a factor of approximately 3.8:1 along the length and moreover the overall flow was limited by the high pressure drop within the system. As a result the thermal output of the combustor cannot always meet the demands of the drying process. Excessive erosion and wear of the walls of the pipes near some of the holes can also be a problem. A computational fluid dynamics (CFD) study was undertaken of the flow characteristics of different designs of sparge pipe and the results validated by flow and pressure measurements on full scale laboratory models. The flow distribution was substantially improved and the overall flow rate increased by approximately 7% by varying the hole diameters and spacings between adjacent holes. In addition much greater increases in predicted overall flow rates can be achieved by reducing the thickness of the pipe wall (whilst maintaining a constant outer diameter) although this may reduce the operating life of the pipe because of erosion and excessive wear. Erosion of the outside of the pipes was studied in near ambient temperature fluidised beds using multiple thin layers of different coloured paints on the outside of the pipes to assess the wear patterns. These patterns were found to be similar to those observed on actual sparge pipes at the end of an operating campaign. Quantitative measurements of the rate of wear of the paint layers indicated that pipe wall erosion can be substantially reduced by reducing the angle of inclination of the downward facing holes in the pipes.

Flow Characteristics of Long Orifices With Rotation and Corner Radiusing

1988 ◽  
Vol 110 (2) ◽  
pp. 213-217 ◽  
Author(s):  
W. F. McGreehan ◽  
M. J. Schotsch
Keyword(s):  
Reynolds Number ◽  
Test Data ◽  
Discharge Coefficient ◽  
Flow Characteristics ◽  
Arbitrary Geometry ◽  
Inlet Velocity ◽  
Corner Radius ◽  
Flow Effects

The discharge coefficient of an orifice is a function of both geometric and flow effects, such as inlet corner radius, orifice length, inlet velocity orientation, and Reynolds number. Loss characteristics are available for each of these effects; however, a need exists for a reasonable method of predicting the discharge coefficient with an arbitrary combination of the above effects. Presented is a technique for calculating the discharge coefficient for arbitrary geometry with results compared to test data.

The Use of Holographic Interferometry for Turbomachinery Fan Evaluation During Rotating Tests

1988 ◽  
Vol 110 (3) ◽  
pp. 393-400 ◽  
Author(s):  
R. J. Parker ◽  
D. G. Jones
Keyword(s):  
Boundary Layer ◽  
Transonic Flow ◽  
Three Dimensional ◽  
Flow Region ◽  
Vibration Modes ◽  
Design Intent ◽  
Tip Leakage ◽  
Fan Behavior ◽  
Boundary Layer Interaction ◽  
Flow Features

Holography has been developed by Rolls-Royce as a technique for routine use in the evaluation of fan designs for aeroengines. It is used to investigate both aerodynamic and mechanical behavior of the rotating fan. Holographic flow visualization provides clear, three-dimensional images of the transonic flow region between the fan blades. Flow features such as shocks, shock/boundary layer interaction, and over-tip leakage vortices can be observed and measured. Holograms taken through an optical derotator allow vibration modes of the rotating fan to be mapped during resonance or flutter. Examples are given of the use of both techniques at rotational speeds up to and in excess of 10,000 rpm. Holography has provided valuable information used to verify and improve numerical modeling of the fan behavior and has been successful in evaluating the achievement of design intent.

Internal flow and external jet characteristics of double serpentine nozzle with different aspect ratio

2017 ◽  
Vol 233 (2) ◽  
pp. 545-560 ◽  
Author(s):  
Sun Xiao-lin ◽  
Wang Zhan-xue ◽  
Zhou Li ◽  
Shi Jing-wei ◽  
Cheng Wen
Keyword(s):  
Aspect Ratio ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Critical Parameters ◽  
Potential Core ◽  
Suppression Effect ◽  
Symmetric Plane ◽  
Flow Features ◽  
In Series ◽  
Jet Characteristics

In order to increase the survivability of the fighter aircraft, the serpentine nozzle has been applied in series of stealth bombers and unmanned aerial vehicles due to its excellent potentiality of evidently suppressing the infrared radiation signatures and radar cross section emitted by engine exhausts. Among the geometric parameters of the serpentine nozzle, the aspect ratio (AR) at the nozzle exit is one of the most critical parameters for the nozzle design as the infrared suppression effect could be greatly enhanced with the increment of AR by strengthening the mixing between the exhaust plume and atmosphere; the aim of this paper is to study the influence of the AR on the flow characteristics of the double serpentine nozzle. The flow features of six double serpentine convergent nozzles, i.e. AR = 3, 5, 7, 9, 11, 15 respectively, were numerically simulated with the shear stress transport κ–ω turbulent model adopted, which had been validated by the experimental data. The characteristics of internal flow and external jet, and the aerodynamic performances of these six nozzles were compared. Results show that the Ma contours at the symmetric plane are different due to the distinct flow accelerations caused by the change of the curvature and the duct height for diverse AR, and the surface pressure and the shock wave features are different correspondingly. The lateral divergence and the lateral convergence characteristics of the nozzle configuration lead to opposite lateral flow under diverse AR, and the change of lateral width induced different lateral pressure gradient, then lead to various lateral vortex distributions. The length of potential core is the contribution of the comprehensive effects of geometry parameters, and it is decreased with the increase of AR due to the dominated effect of the increased mixing area; however, the declining rate is slowed down. The AR of 5 should be chosen for the best aerodynamic performance of the double serpentine nozzle under the qualifications to completely shield the high-temperature turbine.

Numerical Calibration of 3D Printed Five-Hole Probes for the Transonic Flow Regime

2019 ◽  
Author(s):  
Maximilian Passmann ◽  
Stefan aus der Wiesche ◽  
Franz Joos
Keyword(s):  
Flow Regime ◽  
Transonic Flow ◽  
Calibration Method ◽  
Calibration Procedure ◽  
Tip Clearance ◽  
Outer Diameter ◽  
Number Range ◽  
Half Angle ◽  
3D Printed ◽  
Transonic Turbine

Abstract This paper presents a method for a cost- and time-effective calibration procedure for five-hole probes for the transonic flow regime based on additive manufacturing and a numerical calibration routine. The computational setup and calibration routine are described in detail. The calibration procedure is tested on a custom-built L-shaped conical probe of 30° half-angle with a flat tip and an outer diameter of 2.4mm. The probe tip is manufactured in stainless steel using DMLS. Numerical calibration is carried out over a Mach number range of 0.2 to 1.4 and pitch and yaw angles of ±45°. The numerical calibration charts are validated with wind tunnel tests and the expected accuracy of the numerical calibration method is quantified. Exemplary results of area traverses up- and downstream of a linear transonic turbine cascade with tip clearance are presented and discussed briefly.

Flow Characteristics of Double Serpentine Convergent Nozzle With Different Inlet Configuration

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Sun Xiao-Lin ◽  
Wang Zhan-Xue ◽  
Zhou Li ◽  
Shi Jing-Wei ◽  
Cheng Wen
Keyword(s):  
Flow Characteristics ◽  
Complex Flow ◽  
Convergent Nozzle ◽  
Core Flow ◽  
The Core ◽  
Setting Angle ◽  
Swirl Angle ◽  
Swirl Flows ◽  
Flow Features ◽  
Inlet Swirl

Serpentine nozzles have been used in stealth fighters to increase their survivability. For real turbofan aero-engines, the existence of the double ducts (bypass and core flow), the tail cone, the struts, the lobed mixers, and the swirl flows from the engine turbine, could lead to complex flow features of serpentine nozzle. The aim of this paper is to ascertain the effect of different inlet configurations on the flow characteristics of a double serpentine convergent nozzle. The detailed flow features of the double serpentine convergent nozzle including/excluding the tail cone and the struts are investigated. The effects of inlet swirl angles and strut setting angles on the flow field and performance of the serpentine nozzle are also computed. The results show that the vortices, which inherently exist at the corners, are not affected by the existence of the bypass, the tail cone, and the struts. The existence of the tail cone and the struts leads to differences in the high-vorticity regions of the core flow. The static temperature contours are dependent on the distributions of the x-streamwise vorticity around the core flow. The high static temperature region is decreased with the increase of the inlet swirl angle and the setting angle of the struts. The performance loss of the serpentine nozzle is mostly caused by its inherent losses such as the friction loss and the shock loss. The performance of the serpentine nozzle is decreased as the inlet swirl angle and the setting angle of the struts increase.

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