Development of a Stiffness-Based Chemistry Load Balancing Scheme, and Optimization of Input/Output and Communication, to Enable Massively Parallel High-Fidelity Internal Combustion Engine Simulations

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Janardhan Kodavasal ◽  
Kevin Harms ◽  
Priyesh Srivastava ◽  
Sibendu Som ◽  
Shaoping Quan ◽  
...  
Keyword(s):  
Load Balancing ◽  
Combustion Engine ◽  
Mesh Size ◽  
Test Case ◽  
Compression Ignition ◽  
Input Output ◽  
Engine Simulation ◽  
Crank Angle ◽  
Computational Fluid Dynamics Cfd ◽  
Blue Gene

A closed-cycle gasoline compression ignition (GCI) engine simulation near top dead center (TDC) was used to profile the performance of a parallel commercial engine computational fluid dynamics (CFD) code, as it was scaled on up to 4096 cores of an IBM Blue Gene/Q (BG/Q) supercomputer. The test case has 9 × 106 cells near TDC, with a fixed mesh size of 0.15 mm, and was run on configurations ranging from 128 to 4096 cores. Profiling was done for a small duration of 0.11 crank angle degrees near TDC during ignition. Optimization of input/output (I/O) performance resulted in a significant speedup in reading restart files, and in an over 100-times speedup in writing restart files and files for postprocessing. Improvements to communication resulted in a 1400-times speedup in the mesh load balancing operation during initialization, on 4096 cores. An improved, “stiffness-based” algorithm for load balancing chemical kinetics calculations was developed, which results in an over three-times faster runtime near ignition on 4096 cores relative to the original load balancing scheme. With this improvement to load balancing, the code achieves over 78% scaling efficiency on 2048 cores, and over 65% scaling efficiency on 4096 cores, relative to 256 cores.

Development of a Stiffness-Based Chemistry Load Balancing Scheme, and Optimization of I/O and Communication, to Enable Massively Parallel High-Fidelity Internal Combustion Engine Simulations

2015 ◽  
Author(s):  
Janardhan Kodavasal ◽  
Kevin Harms ◽  
Priyesh Srivastava ◽  
Sibendu Som ◽  
Shaoping Quan ◽  
...  
Keyword(s):  
Load Balancing ◽  
Combustion Engine ◽  
Mesh Size ◽  
Test Case ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Engine Simulation ◽  
Output Performance ◽  
Crank Angle ◽  
Blue Gene

A closed-cycle gasoline compression ignition engine simulation near top dead center (TDC) was used to profile the performance of a parallel commercial engine computational fluid dynamics code, as it was scaled on up to 4096 cores of an IBM Blue Gene/Q supercomputer. The test case has 9 million cells near TDC, with a fixed mesh size of 0.15 mm, and was run on configurations ranging from 128 to 4096 cores. Profiling was done for a small duration of 0.11 crank angle degrees near TDC during ignition. Optimization of input/output performance resulted in a significant speedup in reading restart files, and in an over 100-times speedup in writing restart files and files for post-processing. Improvements to communication resulted in a 1400-times speedup in the mesh load balancing operation during initialization, on 4096 cores. An improved, “stiffness-based” algorithm for load balancing chemical kinetics calculations was developed, which results in an over 3-times faster run-time near ignition on 4096 cores relative to the original load balancing scheme. With this improvement to load balancing, the code achieves over 78% scaling efficiency on 2048 cores, and over 65% scaling efficiency on 4096 cores, relative to 256 cores.

scholarly journals Spray-Wall Interactions in a Small-Bore, Multi-Cylinder Engine Operating With Reactivity-Controlled Compression Ignition

2017 ◽  
Author(s):  
Martin L. Wissink ◽  
Scott J. Curran ◽  
Chaitanya Kavuri ◽  
Sage L. Kokjohn
Keyword(s):  
Compression Ignition ◽  
Compelling Evidence ◽  
Cfd Simulations ◽  
Fuel Film ◽  
Reactivity Controlled Compression Ignition ◽  
Spray Penetration ◽  
Crank Angle ◽  
Computational Fluid Dynamics Cfd ◽  
Wall Interactions ◽  
Early Injection

Experimental work on reactivity-controlled compression ignition (RCCI) in a small-bore, multi-cylinder engine operating on premixed iso-octane and direct-injected n-heptane has shown an unexpected combustion phasing advance at early injection timings, which has not been observed in large-bore engines operating under RCCI at similar conditions. In this work, computational fluid dynamics (CFD) simulations were performed to investigate whether spray-wall interactions could be responsible for this result. Comparison of the spray penetration, fuel film mass, and in-cylinder visualization of the spray from the CFD results to the experimentally measured combustion phasing and emissions provided compelling evidence of strong fuel impingement at injection timings earlier than −90 crank angle degrees (°CA) after top dead center (aTDC), and transition from partial to full impingement between −65 and −90°CA aTDC. Based on this evidence, explanations for the combustion phasing advance at early injection timings are proposed along with potential verification experiments.

scholarly journals Spray–Wall Interactions in a Small-Bore, Multicylinder Engine Operating With Reactivity-Controlled Compression Ignition

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Martin L. Wissink ◽  
Scott J. Curran ◽  
Chaitanya Kavuri ◽  
Sage L. Kokjohn
Keyword(s):  
Compression Ignition ◽  
Compelling Evidence ◽  
Cfd Simulations ◽  
Fuel Film ◽  
Reactivity Controlled Compression Ignition ◽  
Spray Penetration ◽  
Crank Angle ◽  
Computational Fluid Dynamics Cfd ◽  
Wall Interactions ◽  
Early Injection

Experimental work on reactivity-controlled compression ignition (RCCI) in a small-bore, multicylinder engine operating on premixed iso-octane, and direct-injected n-heptane has shown an unexpected combustion phasing advance at early injection timings, which has not been observed in large-bore engines operating under RCCI at similar conditions. In this work, computational fluid dynamics (CFD) simulations were performed to investigate whether spray–wall interactions could be responsible for this result. Comparison of the spray penetration, fuel film mass, and in-cylinder visualization of the spray from the CFD results to the experimentally measured combustion phasing and emissions provided compelling evidence of strong fuel impingement at injection timings earlier than −90 crank angle degrees (deg CA) after top dead center (aTDC), and transition from partial to full impingement between −65 and −90 deg CA aTDC. Based on this evidence, explanations for the combustion phasing advance at early injection timings are proposed along with potential verification experiments.

The Compression-Ignition Engine and Its Applicability to British Railway Traction

1933 ◽  
Vol 124 (1) ◽  
pp. 3-61 ◽  
Author(s):  
L. F. R. Fell
Keyword(s):  
Internal Combustion Engine ◽  
High Speed ◽  
Combustion Engine ◽  
Internal Combustion ◽  
High Rate ◽  
Wide Field ◽  
Compression Ignition ◽  
Electric Locomotive ◽  
Compression Ignition Engine ◽  
Railway Traction

The author considers that, while the internal combustion engine is not universally applicable to British railway traction, there is a wide field which can be more economically covered by the oil engine than by other means. Electric transmission is, in spite of high first cost, the most readily adaptable for use in conjunction with the oil engine, and possesses a balance of advantages over all other known systems. The oil-electric locomotive offers a long list of important advantages for railway operation not possessed by other systems. These advantages are, however, offset by high first cost for powers of 1,000 b.h.p. and over. A comparison is drawn between the first cost of steam and oil-electric locomotives for the various duties called for in the service of a British railway. This shows that, while the first cost of the oil-electric main line express passenger locomotive is three times that of the existing steam locomotive, the first costs of branch passenger, medium goods, and shunting steam and oil-electric engines are comparable. This is owing to the cost per brake horse-power required diminishing with increase of size in the case of the steam locomotive, whereas it remains constant in the case of the oil-electric. Owing to the high rate of acceleration necessary the use of the oil-electric system is considered unsuitable as a substitute for dependent electrification of suburban lines. The railway oil engine is a specialized requirement. It must be of the high-speed type running at speeds of up to 1,500 r.p.m., in order to reduce first cost and for other reasons. Details are given of various types of British compression-ignition engines which are considered suitable for British railway work. The author deduces that an engine of twelve-cylinder “V” type and an engine with six cylinders in line, both incorporating the same design and size of cylinder, would fill all the requirements which can be economically met by the oil engine on a British railway. He selects the single sleeve-valve engine design as having the greatest balance of advantages in its favour for railway purposes. Attention is drawn to the importance of simplifying the installation of the compression-ignition engine and various suggestions are put forward to this end. In conclusion the author stresses the importance of the railway companies giving a lead to the internal combustion engine industry as to the railway requirements in size and type of engine, and states that it is the purpose of his paper to assist those concerned in arriving at this immediately important decision.

Innovative exploration of safe in-flightcrew escape options

2018 ◽  
Vol 90 (8) ◽  
pp. 1221-1226
Author(s):  
Sreedhar Karunakaran
Keyword(s):  
Wind Tunnels ◽  
Test Case ◽  
Test Cases ◽  
Flight Crew ◽  
External Interference ◽  
Content Type ◽  
Transport Aircraft ◽  
3D Cad ◽  
Computational Fluid Dynamics Cfd ◽  
Actual Trial

Purpose The purpose of this paper is to explore various in-flight crew escape options of a prototype transport aircraft and finalize the option offering safest crew egress for different combinations of contingencies and flight conditions. Design/methodology/approach Various egress options were explored through simulation in a computational fluid dynamics (CFD) software using aircraft 3D CAD model and scalable digital mannequins. For this, certain important contingencies which best describe the extreme aircraft behaviour were identified. Crew escape options, which have least external interference in expected egress trajectory, were selected. Several test simulations representing each feasible combination of contingency, escape option and flight condition were simulated. The option which offers safe crew escape in each test case is deemed to be the safest egress option for the test aircraft. Findings Among five options explored, crew escape through forward ventral hatch provided the safest crew escape for all test cases. The selected option was validated for robustness with additional test cases modelling different anthropometric characteristics of 5th and 50th percentile pilot populations with different postures. Originality/value In-flight validation of safe crew escape option is infeasible by actual trial. Exploration of safe crew options for required number of test cases by any analytical method or by wind tunnels tests is tedious, time consuming and extremely expensive. On the other hand, exploration of safest crew option by CFD, besides being first of its kind, provides convenient option to configure, test and validate different test cases with unmatched benefits in time, cost and simplicity.

Sign in / Sign up

Export Citation Format

Share Document