Investigation of mixing characteristics of coflow rectangular nozzle of aspect ratio 2 and 3

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Vignesh Kumar Murugesan ◽  
Aravindh Kumar Suseela Moorthi ◽  
Ganapathy Subramanian L. Ramachandran
Keyword(s):  
Aspect Ratio ◽  
High Speed ◽  
Exhaust System ◽  
Commercial Aircraft ◽  
Potential Core ◽  
Sonic Nozzle ◽  
Content Type ◽  
Rectangular Nozzle ◽  
Nozzle Pressure ◽  
Mixing Characteristics

Purpose The purpose of this study is to understand experimentally the mixing characteristics of a two-stream exhaust system with a supersonic Mach 1.5 primary jet that exits the rectangular C-D nozzle surrounded by a sonic secondary jet from a convergent rectangular nozzle by varying the aspect ratio (AR = 2 and 3) similar to those that can be available for future high-speed commercial aircraft. Design/methodology/approach This paper focuses on the experimental results of effects of AR at various expansion levels of jets issued/delivered from a central rectangular convergent-divergent nozzle of AR 2 and 3 surrounded by a coflow from a convergent rectangular sonic nozzle. The lip thickness of the primary nozzle is 2.2 mm. various nozzle pressure ratios (NPRs) ranging from 2, 3, 3.69 and 4 were chosen for pressure measurements. Findings For all the NPRs, AR 3 had a shorter core than AR 2. Also, AR 3 was found to decay faster in the transition and fully developed zones. The lateral plots show that the AR has an influence on the jet spread. Originality/value The structure of waves existing in the potential core of the rectangular coflow jet along with the major and minor axis planes was visualized by the shadowgraph technique.

Characteristics of a co-flowing jet with varying lip thickness and constant bypass ratio

2019 ◽  
Vol 91 (9) ◽  
pp. 1205-1213 ◽  
Author(s):  
Naren Shankar R. ◽  
Kevin Bennett S.
Keyword(s):  
Design Methodology ◽  
Critical Value ◽  
Commercial Aircraft ◽  
Critical Limit ◽  
Potential Core ◽  
Content Type ◽  
Free Jet ◽  
The Past ◽  
Bypass Ratio ◽  
Practical Implications

Purpose Subsonic commercial aircraft operate with turbo-fan engines that operate with moderate bypass ratio (BR) co-flowing jets (CFJ). This study aims to analyse CFJ with constant BR 6.3 and varying primary nozzle lip thickness (LT) to find a critical LT in CFJ below which mixing enhances and beyond which mixing inhibits. Design/methodology/approach CFJ were characterized with a constant BR of 6.3 and varying lip thicknesses. A single free jet with a diameter equal to that of a primary nozzle of the co-flowing jet was also studied for comparison. Findings The results show that within a critical limit, the mixing enhanced with an increase in LT. This was signified by a reduction in potential core length (PCL). Beyond this limit, mixing inhibited leading to the elongation of PCL. This limit was controlled by parameters such as LT and magnitude of BR. Practical implications The BR value of CFJ in the present study was 6.3. This lies under the moderate BR value at which subsonic commercial turbofan operates. Hence, it becomes impervious to study its mixing behavior. Originality/value This is the first effort to find the critical value of LT for a constant BR for compressible co-flow jets. The CFJ with moderate BR and varying LT has not been studied in the past. The present study focuses on finding a critical LT below which mixing enhances and above which mixing inhibits.

Mixing Characteristics and Enhancement of Sonic Elliptic Jets from a Twin Elliptic Orifice

2020 ◽  
Vol 12 (2) ◽  
Author(s):  
S. Parameshwari ◽  
Pradeep Kumar ◽  
S. Thanigaiarasu ◽  
E. Rathakrishnan
Keyword(s):  
Boundary Layer ◽  
Aspect Ratio ◽  
System Design ◽  
Pressure Ratio ◽  
Jet Noise ◽  
Nozzle Pressure Ratio ◽  
Jet Mixing ◽  
Nozzle Pressure ◽  
Mixing Characteristics ◽  
Ir Signature

The knowledge of jet mixing and its enhancement of elliptic jet are important in a propulsion system of aircraft, rocket, and missile’s system design for advancement of combustion via fuel-air mixture increment, lowering the jet noise and reduction of the plume infrared (IR) signature. The jet issuing from a twin elliptic orifice is non-uniform in shape that promotes the faster mixing and it influences by orifice exit conditions, so knowledge of absence of boundary layer and jet mixing characteristics is important. Hence, an experimental work helps to study the jet mixing for a twin elliptic orifice of aspect ratio two at nozzle pressure ratios of one, two, and three. The proximity between the orifices kept as one to 3mm in steps of one. The experimental readings were taken using pitot probe. The results revealed that jet mixing is faster and effective when the proximity between the orifices is closer to each other than the faraway distances at measured nozzle pressure ratios. Difference in orifice jet core exerted a noticeable influence at high proximity levels of nozzle pressure ratio of three and four for elliptic orifice.

Experimental investigation on mixing characteristics of high speed co-flow jets by using tabbed chevron nozzle

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Saravanan A. R. ◽  
Thanigaiarasu S. ◽  
Rakesh Divvela ◽  
Rathakrishnan E.
Keyword(s):  
Experimental Investigation ◽  
Mach Number ◽  
High Speed ◽  
Radial Profile ◽  
Mixing Enhancement ◽  
Primary Flow ◽  
Potential Core ◽  
Mixing Characteristics ◽  
Chevron Nozzle ◽  
Better Than

Abstract The present study investigates the effect of chevron with tab (Tabbed chevron) fixed at the exit of the co-flowing primary nozzle on the mixing characteristics in subsonic and sonic jets. The experiment was conducted for the jet Mach number 0.6 and 0.8. The centerline Mach number decay was calculated for all these jet Mach numbers for the co-flow baseline nozzle, nozzle with chevrons and tabbed chevron (primary flow) nozzle respectively. It was found that tabbed chevron was effective in reducing the potential core length by 88.23% as compared to the chevron nozzle with baseline nozzle. The radial profile also shows that the mixing enhancement by tabbed chevron is better than chevron nozzle.

Experimental investigation on mixing characteristics of high speed co-flow jets by using tabbed chevron nozzle

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Saravanan A. R. ◽  
Thanigaiarasu S. ◽  
Rakesh Divvela ◽  
Rathakrishnan E.
Keyword(s):  
Experimental Investigation ◽  
Mach Number ◽  
High Speed ◽  
Radial Profile ◽  
Mixing Enhancement ◽  
Primary Flow ◽  
Potential Core ◽  
Mixing Characteristics ◽  
Chevron Nozzle ◽  
Better Than

Abstract The present study investigates the effect of chevron with tab (Tabbed chevron) fixed at the exit of the co-flowing primary nozzle on the mixing characteristics in subsonic and sonic jets. The experiment was conducted for the jet Mach number 0.6 and 0.8. The centerline Mach number decay was calculated for all these jet Mach numbers for the co-flow baseline nozzle, nozzle with chevrons and tabbed chevron (primary flow) nozzle respectively. It was found that tabbed chevron was effective in reducing the potential core length by 88.23% as compared to the chevron nozzle with baseline nozzle. The radial profile also shows that the mixing enhancement by tabbed chevron is better than chevron nozzle.

Influence of ageing treatment on microstructure, mechanical properties and adhesive wear behaviour of 6063 aluminium alloy

2014 ◽  
Vol 66 (4) ◽  
pp. 520-524 ◽  
Author(s):  
Serkan Büyükdoğan ◽  
Süleyman Gündüz ◽  
Mustafa Türkmen
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
High Speed ◽  
Al Alloys ◽  
Wear Behaviour ◽  
Al Alloy ◽  
Strain Ageing ◽  
Content Type ◽  
Static Strain ◽  
Structural Applications

Purpose – The paper aims to provide new observations about static strain ageing in aluminium (Al) alloys which are widely used in structural applications. Design/methodology/approach – The present work aims to provide theoretical and practical information to industries or researchers who may be interested in the effect of static strain ageing on mechanical properties of Al alloys. The data are sorted into the following sections: introduction, materials and experimental procedure, results and discussion and conclusions. Findings – Tensile strength, proof strength (0.2 per cent) and percentage elongation measurement were used to investigate the effect of strain ageing on the mechanical properties. Wear tests were performed by sliding the pin specimens, which were prepared from as-received, solution heat-treated, deformed and undeformed specimens after ageing, on high-speed tool steel (64 HRC). It is concluded that the variations in ageing time improved the strength and wear resistance of the 6063 Al alloy; however, a plastically deformed solution-treated alloy has higher strength and wear resistance than undeformed specimens for different ageing times at 180°C. Practical implications – A very useful source of information for industries using or planning to produce Al alloys. Originality/value – This paper fulfils an identified resource need and offers practical help to the industries.

scholarly journals Aspect Ratio Driven Relationship between Nozzle Internal Flow and Supersonic Jet Mixing

Aerospace ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 78
Author(s):  
Kalyani Bhide ◽  
Kiran Siddappaji ◽  
Shaaban Abdallah
Keyword(s):  
Boundary Layer ◽  
Aspect Ratio ◽  
Nozzle Exit ◽  
Supersonic Jet ◽  
Internal Flow ◽  
Shear Stresses ◽  
Loss Mechanism ◽  
Potential Core ◽  
Jet Mixing ◽  
Aspect Ratios

This work attempts to connect internal flow to the exit flow and supersonic jet mixing in rectangular nozzles with low to high aspect ratios (AR). A series of low and high aspect ratio rectangular nozzles (design Mach number = 1.5) with sharp throats are numerically investigated using steady state Reynolds-averaged Navier−Stokes (RANS) computational fluid dynamics (CFD) with k-omega shear stress transport (SST) turbulence model. The numerical shadowgraph reveals stronger shocks at low ARs which become weaker with increasing AR due to less flow turning at the throat. Stronger shocks cause more aggressive gradients in the boundary layer resulting in higher wall shear stresses at the throat for low ARs. The boundary layer becomes thick at low ARs creating more aerodynamic blockage. The boundary layer exiting the nozzle transforms into a shear layer and grows thicker in the high AR nozzle with a smaller potential core length. The variation in the boundary layer growth on the minor and major axis is explained and its growth downstream the throat has a significant role in nozzle exit flow characteristics. The loss mechanism throughout the flow is shown as the entropy generated due to viscous dissipation and accounts for supersonic jet mixing. Axis switching phenomenon is also addressed by analyzing the streamwise vorticity fields at various locations downstream from the nozzle exit.

Impacts of high-speed railway on the industrial pollution emissions in China

Kybernetes ◽  
2020 ◽  
Vol 49 (11) ◽  
pp. 2713-2735 ◽  
Author(s):  
Xiaomin Fan ◽  
Yingzhi Xu ◽  
Yongqing Nan ◽  
Baoli Li ◽  
Haiya Cai
Keyword(s):  
Environmental Effects ◽  
Industrial Pollution ◽  
High Speed ◽  
Assessment Method ◽  
Economic Effects ◽  
High Speed Railway ◽  
Central Cities ◽  
Content Type ◽  
Pollution Emissions ◽  
The Impact

Purpose The purpose of this paper is to analyse the impact of high-speed railway (HSR) on industrial pollution emissions using the data for 285 prefecture-level cities in China from 2004 to 2016. Design/methodology/approach The research method used in this paper is the multi-period difference-in-differences (DID) model, which is an effective policy effect assessment method. To further address the issue of endogeneity, the DID integrated with the propensity score matching (PSM-DID) approach is employed to eliminate the potential self-selection bias. Findings The results show that the HSR has significantly reduced industrial pollution emissions, which is validated by several robustness tests. Compared with peripheral cities, HSR exerts a greater impact on industrial pollution emissions in central cities. In addition, the mechanism test reveals that the optimised allocation of inter-city industries is an important channel for HSR to mitigate industrial pollution emissions, and this is closely related to the location of HSR stations. Originality/value Previous studies have paid more attention to evaluating the economic effects of HSR, however, most of these studies overlook its environmental effects. Consequently, the impact of HSR on industrial pollution emissions is led by using multi-period DID models in this paper, in which the environmental effects are measured. The results of this paper can provide a reference for the pollution reduction policies and also the coordinated development of economic growth and environmental quality.

Comparison of the reluctance laminated and solid rotor synchronous machine operating at high temperatures

2019 ◽  
Vol 38 (4) ◽  
pp. 1111-1119 ◽  
Author(s):  
Marcin Lefik ◽  
Krzysztof Komeza ◽  
Ewa Napieralska-Juszczak ◽  
Daniel Roger ◽  
Piotr Andrzej Napieralski
Keyword(s):  
High Speed ◽  
Design Methodology ◽  
Three Dimensional ◽  
Synchronous Machine ◽  
Point Of View ◽  
Heat Sources ◽  
Model Calculations ◽  
Content Type ◽  
Thermal Phenomenon ◽  
Practical Implications

Purpose The purpose of this paper is to present a comparison between reluctance synchronous machine-enabling work at high internal temperature (HT° machine) with laminated and solid rotor. Design/methodology/approach To obtain heat sources for the thermal model, calculations of the electromagnetic field were made using the Opera 3D program including effect of rotation and the resulting eddy current losses. To analyse the thermal phenomenon, the 3D coupled thermal-fluid (CFD) model is used. Findings The presented results show clearly that laminated construction is much better from a point of view of efficiency and temperature. However, solid construction can be interesting for high speed machines due to their mechanical robustness. Research limitations/implications The main problem, despite the use of parallel calculations, is the long calculation time. Practical implications The obtained simulation and experimental results show the possibility of building a machine operating at a much higher ambient temperature than it was previously produced for example in the vicinity of the aircraft turbines. Originality/value The paper presents the application of fully three-dimensional coupled electromagnetic and thermal analysis of new machine constructions designed for elevated temperature.

Characteristic properties of AlTiN and TiN coated HSS materials

2015 ◽  
Vol 67 (2) ◽  
pp. 172-180 ◽  
Author(s):  
Mumin Sahin ◽  
Cenk Misirli ◽  
Dervis Özkan
Keyword(s):  
Surface Roughness ◽  
Tensile Strength ◽  
High Speed ◽  
Cutting Tools ◽  
High Speed Steel ◽  
Wear Properties ◽  
Content Type ◽  
X Ray ◽  
Number Of Cycles ◽  
Future Work

Purpose – The purpose of this paper is to examine mechanical and metallurgical properties of AlTiN- and TiN-coates high-speed steel (HSS) materials in detail. Design/methodology/approach – In this study, HSS steel parts have been processed through machining and have been coated with AlTiN and TiN on physical vapour deposition workbench at approximately 6,500°C for 4 hours. Tensile strength, fatigue strength, hardness tests for AlTiN- and TiN-coated HSS samples have been performed; moreover, energy dispersive X-ray spectroscopy and X-ray diffraction analysis and microstructure analysis have been made by scanning electron microscopy. The obtained results have been compared with uncoated HSS components. Findings – It was found that tensile strength of TiAlN- and TiN-coated HSS parts is higher than that of uncoated HSS parts. Highest tensile strength has been obtained from TiN-coated HSS parts. Number of cycles for failure of TiAlN- and TiN-coated HSS parts is higher than that for HSS parts. Particularly TiN-coated HSS parts have the most valuable fatigue results. However, surface roughness of fatigue samples may cause notch effect. For this reason, surface roughness of coated HSS parts is compared with that of uncoated ones. While the average surface roughness (Ra) of the uncoated samples was in the range of 0.40 μm, that of the AlTiN- and TiN-coated samples was in the range of 0.60 and 0.80 μm, respectively. Research limitations/implications – It would be interesting to search different coatings for cutting tools. It could be the good idea for future work to concentrate on wear properties of tool materials. Practical implications – The detailed mechanical and metallurgical results can be used to assess the AlTiN and TiN coating applications in HSS materials. Originality/value – This paper provides information on mechanical and metallurgical behaviour of AlTiN- and TiN-coated HSS materials and offers practical help for researchers and scientists working in the coating area.

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