Srinivasa Krishna Addepalli
@iittp.ac.in
Ramanujan Fellow at Mechanical Engineering Department, IIT Tirupati
Indian Institute of Technology Tiruapti
RESEARCH, TEACHING, or OTHER INTERESTS
Mechanical Engineering, Energy, Automotive Engineering, General Energy
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Srinivasa Krishna Addepalli, Michael Pamminger, Riccardo Scarcelli, and Thomas Wallner
SAGE Publications
Gasoline compression ignition (GCI) is a promising strategy to achieve high thermal efficiency and low emissions with limited modifications to the conventional diesel engine hardware. It is a partially premixed concept, which derives its superiority from higher volatility and longer ignition delay of gasoline-like fuels combined with higher compression ratio typical of diesel engines. The present study investigates the combustion process in a GCI engine operating with different injection strategies using computational fluid dynamics (CFD). Simulations are carried out on a single cylinder of a multi cylinder heavy-duty compression ignition engine, which operates at a compression ratio of 17:1 and an engine speed of 1038 rev/min. Two different injection strategies viz., late injection (LI), and early pilot injection (EP) are investigated to understand their impact on combustion and performance of the engine. Renormalized group (RNG) k-ε model is used to describe in-cylinder turbulence and KH RT model is used to simulate the fuel spray breakup. The developed CFD methodology is validated against relevant experimental data under a wide range of operating conditions for each injection strategy. The developed CFD methodology was found to capture the engine combustion behavior quite well. Based on the validated CFD model, the differences in the progress of combustion event for the two injection strategies is highlighted. It was found that a larger pilot fuel mass fraction results in a steeper rise in the initial heat release rate which in turn influences the transition to mixing controlled combustion. In line with the experimental data, the study showed that the late pilot injection strategy with three injection pulses, results in higher performance compared to the other conditions.
Michael Pamminger, Srinivasa Krishna Addepalli, Riccardo Scarcelli, and Thomas Wallner
SAE International
Srinivasa Krishna Addepalli, Yuanjiang Pei, Yu Zhang, and Riccardo Scarcelli
Elsevier BV
Srinivasa Krishna Addepalli, Gina M. Magnotti, Sibendu Som, Pushkar Sheth, Vijayaselvan Jayakar, Adam Klingbeil, and Thomas Lavertu
American Society of Mechanical Engineers
Abstract Diesel engines are one of the most commonly used combustion systems for heavy-duty applications like locomotives. Although computational fluid dynamics (CFD) modeling of diesel engines is a mature research topic, CFD modeling of large-bore engines like those used in locomotives has not been as extensively studied as their smaller bore on-road and stationary counterparts. The present paper aims at identifying and outlining best practices for performing 3D CFD simulations of locomotive diesel engines and comparing them with the established best practices for heavy-duty diesel engines in the literature. The locomotive diesel engine considered in this study has a bore of 168mm and operates at speeds of up to 1800 rpm. Open cycle engine CFD simulations were carried out for both motored and fired cases. Two turbulence models viz., Re-Normalization group (RNG) k-ε model and Reynolds stress model (RSM) were used in this study to assess their performance. The fuel spray break up was modelled using Kelvin Helmholtz and Rayleigh Taylor (KH-RT) model. A grid and statistical convergence study was performed to assess the effect of mesh size on the predicted results. It was found that a minimum cell size of 0.25 mm near the fuel spray and 1 mm in the rest of the cylinder was sufficient to achieve grid convergence in terms of spray and combustion characteristics. The boundary wall temperatures are shown to affect the in-cylinder pressure predictions. Higher wall temperatures were found to reduce the trapped mass and increase the peak motored pressure. The CFD model was validated by comparing the simulation results with the experimental measurements at full rated power. It was found that the RSM was able to capture the combustion characteristics more accurately compared to RNG k-ε model. Overall, the CFD model was able to predict the engine combustion and performance characteristics at three injection timings.
Srinivasa Krishna Addepalli, Riccardo Scarcelli, Yan Wang, Ryan Vojtech, Raj Kumar, and James Cigler
SAE International
Srinivasa Krishna Addepalli, Michael Pamminger, Riccardo Scarcelli, Buyu Wang, and Thomas Wallner
SAE International
Srinivasa Krishna Addepalli, Michael Pamminger, Riccardo Scarcelli, and Thomas Wallner
American Society of Mechanical Engineers
Abstract Gasoline compression ignition (GCI) is a promising way to achieve high thermal efficiency and low emissions while leveraging conventional diesel engine hardware. GCI is a partially premixed combustion concept, which derives its superiority from good volatility and long ignition delay of gasoline-like fuels. The present study investigates the interaction between the piston bowl and the spray plume of a compression ignition engine that operates with a late fuel injection strategy using computational fluid dynamics (CFD) analysis. Simulations were carried out on a single cylinder of a multi-cylinder heavy-duty compression ignition engine. The engine operates at a speed of 1038 rev/min., and a compression ratio of 17. Incylinder turbulence was modelled using RNG k-ε model and the fuel spray break up was modelled using KH-RT model. A reduced chemical kinetic mechanism was used to model combustion chemistry. After validating the combustion and performance characteristics of the baseline piston against experimental results, several new piston bowl designs were generated using CAESES. Full cycle engine simulations for four selected bowl profiles were carried out. The results compare the spray-bowl interaction of the new piston bowl designs with the baseline design. It was found that the lip location and center depth of the bowl profile are the critical design parameters that influence the air utilization and heat transfer losses. The impact of spray-bowl interaction on thermal efficiency of the engine is investigated.
Om Prakash Saw, Srinivasa Krishna Addepalli, and J.M. Mallikarjuna
SAE International
S. Krishna Addepalli and J. M. Mallikarjuna
Springer Science and Business Media LLC
Om Prakash Saw, Srinivasa Krishna Addepalli, and J M Mallikarjuna
SAE International
Yashas Karaya, Srinivasa Krishna Addepalli, and J M Mallikarjuna
SAE International
S. Krishna Addepalli and J.M. Mallikarjuna
Elsevier BV
Yashas Karaya, Srinivasa Krishna Addepalli, and J M Mallikarjuna
SAE International
Krishna S Addepalli and J M Mallikarjuna
SAE International
S Krishna Addepalli, Om Prakash Saw, and J M Mallikarjuna
SAE International
Addepalli S. Krishna, J.M. Mallikarjuna, and Davinder Kumar
Elsevier BV
Addepalli S Krishna, Jawali Maharudrappa Mallikarjuna, Kumar Davinder, and Y Ramachandra Babu
SAE International
JM Mallikarjuna, Krishna Addepalli, Y Ramachandra Babu, and Davinder Kumar
SAE International