Impact of additives in Jet-A fuel blends on combustion, emission and exergetic analysis using a micro-gas turbine engine

The role of nanoparticles and nanofluid additives for biodiesel has gained consistent position in the current trend as they contribute to increase the performance of the engine with lower e...

The effect of engine emission on canola biodiesel blends with TiO2

The experimental analysis of base pressure in a high-speed compressible flow is carried out. The flow is made to expand abruptly from the nozzle into an enlarged duct at fifteen sonic and supersonic Mach numbers. The analysis is made for variation in the nozzle pressure ratio (NPR), length to diameter ratio, and area ratio. The effect of active micro-jets on the base and wall pressure is assessed. The data visualization of the huge experimental data generated is performed using heat maps. For the first time, six back-propagation neural network models (BPMs) are developed based on input and output possibilities to predict the pressure in high-speed flows. The experimental analysis revealed that depending upon the type of expansion, the base pressure changes. A jet of air blown at the base using micro-jets is found to be effective in increasing the base pressure during the under-expansion regime, while the wall pressure remains unaffected. The data visualization provided an insight into the highest impact on the base pressure by the NPR. The six BPMs with two hidden layers having four neurons per layer are found to be most suitable for the regression analysis. BPM 5 and BPM 6 accurately predict the highly non-linear data of the base and wall pressure.

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Investigation and back-propagation modeling of base pressure at sonic and supersonic Mach numbers

In this present study, the compression ignition engine was designed to run on CIME (Calophyllum inophyllum methyl ester) biodiesel with nanoparticles. The TiO2 nanoparticle is added to the biodiese...

Effect of TiO2 and nozzle geometry on diesel emissions fuelled with biodiesel blends

Experimental study on the mean flow characteristics of a supersonic multiple jet configuration

The mixing characteristic of circular jet with elliptical throat is studied at different levels of expansion of the nozzle. Two kinds of configurations are studied in this paper, elliptical throat ...

Flow field and acoustic characteristics of elliptical throat CD nozzle

In this paper, we study the pressure energy decay, acoustic and mixing characteristics of non-circular jet with inverted triangular tabs at different ranges of aspect ratio. The centre line...

Acoustic and mixing characteristic of CD nozzle with inverted triangular tabs

Aerodynamic mixing characteristics of the elliptical throat of the convergent divergent nozzle with an identical circular exit of aspect ratio 3 were studied computationally and experimentally. To determine the aerodynamic characteristics during mixing, the pressure distribution and pressure profiles were calibrated along the major and minor axes. The pressure variation in the orifice and nozzle shows that the energy decay in the nozzle dissipates faster than the jet from the orifice. Moreover, we visualised the pressure oscillation of the nozzle and orifices is closer to each other. In addition to that, we have also seen that the energy decay of both jets is approximately close to one another. The mixing promoting capability decreases as the area of the elliptical throat and the pressure gradient of the nozzle decrease. The computational results are evaluated with experimental values. The jet bifurcation is captured using StarCCM+.

Mixing characteristics of elliptical throat sonic jets from orifice and nozzle

Purpose




The purpose of this paper is to present the results of mixing promotion and screech frequency of controlled elliptical supersonic jet.




Design/methodology/approach




Flow field characteristics of low-aspect-ratio elliptical jets are examined at over-expanded, under-expanded and correctly expanded conditions. The tabs are placed at elliptical jet exit along the major and minor axes.




Findings




The results show that the mixing done by the minor axis is superior to the tabs along major axis. At all pressure ratios, the content of jet noise and the frequency are high for the tabs along the major axis because of increase in the amplitude of screech frequency. Further the tabs along minor axis show a dominance of large-scale vertical structures. In under-expanded conditions, the shock cell shows the rapid change because of the presence of tabs. The tabs along minor axis are making the shock weaker, hence no evidence of axis switching.




Practical implications




To achieve the greater performance of jet, the authors need to reduce the potential core length of the issuing jet. This can be achieved by implementing different types of tabs at the exit of the nozzle.




Originality/value




The present paper represents the flow of controlled jet using inverted triangular tabs. By achieving the controlled jet flow, the performance of propulsion systems can be improved. This can be used in systems such as combustion chamber, missile’s noise reduction and thrust vector control.

Flow field and acoustics characteristics of elliptical jet

Abstract This paper presents the experimental results on the flow characteristics of a suddenly expanded flow from subsonic and sonic nozzles. The present study employs passive control in the form of a rib to investigate the base pressure for the enlarged duct. The nozzle pressure ratio (NPR) was varied from 1 to 7. The length to diameter ratio of the enlarged duct was varied from 0.5D to 6D. The aspect ratio of the rib was varied from 0.45 to 1.25. The experimental results showed that the base pressure was strongly influenced by the aspect ratio of the rib at a given L/D ratio. For L/D = 0.5, NPR 3 was found to be critical as seen from the increasing trend in base pressure with NPR. The present study explicitly reveals that, the base pressure in a suddenly expanded axi-symmetric duct can be controlled by employing a rib of appropriate aspect ratio as a passive control device.

K. Vijayaraja

Papers

Flow field and acoustic characteristics of elliptical throat CD nozzle

Acoustic and mixing characteristic of CD nozzle with inverted triangular tabs

Mixing characteristics of elliptical throat sonic jets from orifice and nozzle

Flow field and acoustics characteristics of elliptical jet

Base Pressure Control with Annular Ribs