Computational Analysis of Straight Nozzle: Technical Note

2019 ◽  
Vol 11 (2) ◽  
Author(s):  
F. Ferdaus ◽  
R. Sridhar ◽  
G. Sathishkumar ◽  
S. Sivabalan
Keyword(s):  
Flow Separation ◽  
Supersonic Flows ◽  
Technical Note ◽  
Flow Conditions ◽  
Convergent Nozzle ◽  
Turbine Engine ◽  
Sonic Flow ◽  
Induced Flow ◽  
Exit Mach Number ◽  
Maximum Thrust

Most of the modern aircraft and military aircraft are powered by the modern gas turbine engine. They have nozzles to produce the required speed. Depending upon the required exit Mach number, a nozzle can be designed to be used for subsonic and supersonic flows. For the sonic flows, the convergent nozzle is used and for supersonic flows a convergent–divergent (CD) nozzle is used. In a CD nozzle, a straight nozzle flow is accelerated from low subsonic to sonic velocity at the throat and further expanded to supersonic velocities at the exit. This paper focuses on designing a straight nozzle to attain super-sonic flow and optimizing it to achieve maximum thrust without flow separation due to shock waves. This research also confirms that at which angle of deflection on the divergent portion produces more speed. The flow conditions were selected in view of the pressure, temperature and gases that are accessible at the exit of the combustion chamber. At the exit of the nozzle, the shock induced flow separation due to, over, under and optimum expansion conditions were studied.

CFD Analysis of Aircraft Curved C-D Nozzle: Technical Note

2019 ◽  
Vol 11 (3) ◽  
Author(s):  
F. Ferdaus ◽  
S. Sivaganesan ◽  
C. Dhanasekaran ◽  
G. Sathishkumar ◽  
S. Sivabalan
Keyword(s):  
Mach Number ◽  
Technical Note ◽  
Cfd Analysis ◽  
Flow Conditions ◽  
Flow Properties ◽  
Subsonic Flows ◽  
Gas Dynamic ◽  
Sonic Flow ◽  
Exit Mach Number ◽  
Gas Dynamic Equations

A nozzle for the aircraft can be designed by considering the exit Mach number. In order to get a premeditated Mach number, we need to convert pressure energy into kinetic energy by using a nozzle. Convergent nozzles are utilized for subsonic flows while Convergent-Divergent (C-D) nozzle is utilized for supersonic flows. Curved nozzle flow is accelerated from low subsonic to sonic velocity at the throat and further expanded to supersonic velocities at the exit, in a C-D nozzle. This paper details the relevancies on designing a curved nozzle to attain super-sonic flow and maximizing the optimal thrust and devoid of flow separation due to shock waves. The navigation of the flow must be parallel to the axis of the nozzle for achieving extreme thrust and proficiency. Based on the fundamental gas dynamic equations, this study aims to develop a theoretical approach for the calculation of the flow properties along the axis of the C-D Nozzle. The flow conditions were selected in consideration of the pressure, temperature and gases accessible at the exit of the combustion chamber.

Technical Note: Finite State Induced Flow Model in Vortex Ring State

2000 ◽  
Vol 45 (4) ◽  
pp. 318-320 ◽  
Author(s):  
Chengjian He ◽  
C. S. Lee ◽  
Weibin Chen
Keyword(s):  
Vortex Ring ◽  
Flow Model ◽  
Technical Note ◽  
Finite State ◽  
Induced Flow ◽  
Vortex Ring State

Computational investigation of axi-symmetric plume induced flow separation

2019 ◽  
Vol 160 ◽  
pp. 106-115
Author(s):  
Semih Olcmen ◽  
Gary Cheng ◽  
Richard Branam ◽  
Yitong Gao ◽  
John Baker
Keyword(s):  
Flow Separation ◽  
Computational Investigation ◽  
Induced Flow

scholarly journals Comparison of Blade Element Method and CFD Simulations of a 10 MW Wind Turbine

Fluids ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 73 ◽  
Author(s):  
Galih Bangga
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Separation ◽  
Spatial Interpolation ◽  
Flow Conditions ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Correction Terms ◽  
Selection Of ◽  
Blade Element

The present studies deliver the computational investigations of a 10 MW turbine with a diameter of 205.8 m developed within the framework of the AVATAR (Advanced Aerodynamic Tools for Large Rotors) project. The simulations were carried out using two methods with different fidelity levels, namely the computational fluid dynamics (CFD) and blade element and momentum (BEM) approaches. For this purpose, a new BEM code namely B-GO was developed employing several correction terms and three different polar and spatial interpolation options. Several flow conditions were considered in the simulations, ranging from the design condition to the off-design condition where massive flow separation takes place, challenging the validity of the BEM approach. An excellent agreement is obtained between the BEM computations and the 3D CFD results for all blade regions, even when massive flow separation occurs on the blade inboard area. The results demonstrate that the selection of the polar data can influence the accuracy of the BEM results significantly, where the 3D polar datasets extracted from the CFD simulations are considered the best. The BEM prediction depends on the interpolation order and the blade segment discretization.

scholarly journals Shock-Induced Flow Separation in an Overexpanded Supersonic Planar Nozzle

AIAA Journal ◽  
2020 ◽  
Vol 58 (5) ◽  
pp. 2122-2131 ◽  
Author(s):  
B. Zebiri ◽  
A. Piquet ◽  
A. Hadjadj ◽  
S. B. Verma
Keyword(s):  
Flow Separation ◽  
Induced Flow

scholarly journals Mitigation of shock-induced flow separation using magnetohydrodynamic flow control

Sadhana ◽  
2017 ◽  
Vol 42 (3) ◽  
pp. 379-390
Author(s):  
R Balasubramanian ◽  
K Anandhanarayanan ◽  
R Krishnamurthy ◽  
Debasis Chakraborty
Keyword(s):  
Flow Control ◽  
Flow Separation ◽  
Magnetohydrodynamic Flow ◽  
Induced Flow

Compensation of Intake Induced Flow Non-Uniformities With Compressor Blade Lean Angle Changes

2009 ◽  
Author(s):  
Ioannis Templalexis ◽  
Vassilios Pachidis ◽  
Petros Kotsiopoulos
Keyword(s):  
Gas Turbine ◽  
Flow Simulation ◽  
Gas Turbine Engine ◽  
Compressor Blade ◽  
Design Stage ◽  
Computational Time ◽  
Turbine Engine ◽  
Lean Angle ◽  
Compressor Performance ◽  
Induced Flow

The compression system has traditionally drawn most of the attention concerning the gas turbine engine performance assessment and design procedure. It is the most vulnerable component to flow fluctuations within a gas turbine engine. In particular this study focuses on performance deviations, between an installed and an uninstalled compressor. Test results acquired from a test bed installation will differ from these recorded when the compressor operates as an integral part of the engine. The upstream duct, whether an intake or an interstage duct, will affect the flow field pattern ingested into the compressor. The case studies presented into this work aim to mostly qualify the effect of boundary layer growth along the upstream duct walls, upon compressor performance. Additionally, compressor performance response on blade lean angle variation is being addressed, with the aim of acquiring an understanding as to how compressor blade lean angle changes interact with intake induced flow non uniformities. Such studies are usually conducted during the preliminary design stage, before the compressor is built. Consequently, experimental performance investigation is excluded at this stage of development. Computer aided simulation techniques are between the few if not the only option for compressor performance prediction. Given the fact that many such design parameters need to be assessed under the time pressure exerted by the tight compressor development program, the compressor flow simulation technique used needs to provide reliable results while consuming the least possible computational time. Such a low computational time compressor flow simulation method, among others, is the two dimensional (2D) streamline curvature (SLC) method, being applied within the frame of reference of the current study. The paper is introduced by a brief discussion on SLC method that was proposed more than 50 years ago. Then a reference is made to the Radial Equilibrium Equation (REE) which is the mathematical basis of the code, commenting on the assumptions that were undertaken. Subsequently the influence of the intake presence on the compressor inlet radial flow distribution is being addressed, with the aim of adjusting compressor blade inlet lean angle, in order to minimize compressor performance deterioration. Finally the paper is concluded with a discussion of the results.

scholarly journals Technical Note: The use of an interrupted-flow centrifugation method to characterise preferential flow in low permeability media

2015 ◽  
Vol 12 (1) ◽  
pp. 67-92
Author(s):  
R. A. Crane ◽  
M. O. Cuthbert ◽  
W. Timms
Keyword(s):  
Preferential Flow ◽  
Molecular Diffusion ◽  
Breakthrough Curves ◽  
Technical Note ◽  
Dual Porosity ◽  
Low Permeability ◽  
Efficiency Coefficient ◽  
Transport Modelling ◽  
Induced Flow ◽  
Interrupted Flow

Abstract. We present an interrupted-flow centrifugation technique to characterise preferential flow in low permeability media. The method entails a minimum of three phases: centrifuge induced flow, no flow and centrifuge induced flow, which may be repeated several times in order to most effectively characterise multi-rate mass transfer behaviour. In addition, the method enables accurate simulation of relevant in situ total stress conditions during flow by selecting an appropriate centrifugal force level. We demonstrate the utility of the technique for characterising the hydraulic properties of smectite clay dominated core samples. All samples exhibited a non-Fickian tracer breakthrough (early tracer arrival), combined with a decrease in tracer concentration immediately after each period of interrupted-flow. This is indicative of dual (or multi) porosity behaviour, with solute migration predominately via advection during induced flow, and via molecular diffusion (between the preferential flow network(s) and the low hydraulic conductivity domain) during interrupted-flow. Tracer breakthrough curves were simulated using a bespoke dual porosity model with excellent agreement between the data and model output (Nash–Sutcliffe model efficiency coefficient was >0.97 for all samples). In combination interrupted-flow centrifuge experiments and dual porosity transport modelling are shown to be a powerful method to characterise preferential flow in low permeability media.

Dynamic Effects of Shock-Induced Flow Separation

1975 ◽  
Vol 12 (2) ◽  
pp. 86-92 ◽  
Author(s):  
Lars E. Ericsson
Keyword(s):  
Flow Separation ◽  
Dynamic Effects ◽  
Induced Flow
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