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Research Papers: Internal Combustion Engines

Engine-Control Impact on Energy Balances for Two-Stroke Engines for 10–25 kg Remotely Piloted Aircraft

[+] Author and Article Information
Joseph K. Ausserer

USAF Test Pilot School,
220 Wolfe Avenue,
Edwards AFB, CA 93524
e-mail: Joseph.Ausserer@gmail.com

Marc D. Polanka

Air Force Institute of Technology,
2950 Hobson Way,
WPAFB, OH 45433
e-mail: Marc.Polanka@afit.edu

Paul J. Litke

Air Force Research Laboratory,
1950 7th Street,
WPAFB, OH 45433
e-mail: Paul.Litke.3@us.af.mil

Jacob A. Baranski

Innovative Scientific Solutions Inc.,
1950 7th Street,
WPAFB, OH 45433
e-mail: Jacob.Baranski.ctr@us.af.mil

Contributed by the IC Engine Division of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received January 1, 2018; final manuscript received January 22, 2018; published online July 5, 2018. Editor: David Wisler. This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. Approved for public release; distribution is unlimited.

J. Eng. Gas Turbines Power 140(11), 112803 (Jul 05, 2018) (18 pages) Paper No: GTP-18-1003; doi: 10.1115/1.4039466 History: Received January 01, 2018; Revised January 22, 2018

The rapid expansion of the market for remotely piloted aircraft (RPA) includes a particular interest in 10–25 kg vehicles for monitoring, surveillance, and reconnaissance. Power-plant options for these aircraft are often 10–100 cm3 internal combustion engines (ICEs). The present study builds on a previous study of loss pathways for small, two-stroke engines by quantifying the trade space among energy pathways, combustion stability, and engine controls. The same energy pathways are considered in both studies—brake power, heat transfer from the cylinder, short circuiting, sensible exhaust enthalpy, and incomplete combustion. The engine controls considered in the present study are speed, equivalence ratio, combustion phasing (ignition timing), cooling-air flow rate, and throttle. Several options are identified for improving commercial-off-the-shelf (COTS)-engine efficiency and performance for small, RPA. Shifting from typical operation at an equivalence ratio of 1.1–1.2 to lean operation at an equivalence ratio of 0.8–0.9 results in a 4% (absolute) increase in fuel-conversion efficiency at the expense of a 10% decrease in power. The stock, linear timing maps are excessively retarded below 3000 rpm, and replacing them with custom spark timing improves ease of engine start. Finally, in comparison with conventional-size engines, the fuel-conversion efficiency of the small, two-stroke ICEs improves at throttled conditions by as much as 4–6% (absolute) due primarily to decreased short-circuiting. When no additional short-circuiting mitigation techniques are employed, running a larger engine at partial throttle may lead to an overall weight savings on longer missions. A case study shows that at 6000 rpm, the 3W-55i engine at partial throttle will yield an overall weight saving compared to the 3W-28i engine at wide-open throttle (WOT) for missions exceeding 2.5 h (at a savings of ∼5 g/min).

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References

Jenkins, D. , and Vasigh, B. , 2013, The Economic Impact of Unmanned Aircraft Systems Integration in the United States, Association for Unmanned Vehicle Systems International, Arlington, VA.
Cadou, C. , and Moulton, N. , 2003, “ Performance Measurement and Scaling in Small Internal Combustion Engines,” AIAA Paper No. 2003-0671.
Menon, S. , and Cadou, C. , 2014, “ Scaling of Miniature Piston-Engine Performance—Part 1: Overall Engine Performance,” J. Propul. Power, 29(4), pp. 774–787. [CrossRef]
Taylor, C. F. , 1985, The Internal Combustion Engine in Theory and Practice, (Thermodynamics, Fluid Flow, Performance, Vol. 1), 2nd ed., MIT Press, Cambridge, UK.
Taylor, C. F. , 1985, The Internal Combustion Engine in Theory and Practice, (Combustion, Fuels, Materials, Design, Vol. 2), 2nd ed., MIT First Press, Cambridge, UK.
Heywood, J. B. , 1988, Internal Combustion Engine Fundamentals, McGraw-Hill, New York.
Heywood, J. B. , and Sher, E. , 1999, The Two-Stroke Cycle Engine, Taylor & Francis Group, New York.
Edwards, K. D. , Wagner, R. M. , Tom, E. , Briggs, J. , and Theiss, T. J. , 2011, “ Defining Engine Efficiency Limits,” 17th Directions in Engine-Efficiency and Emissions Research Conference (DEER), Detroit, MI, Oct. 3–6.
Menon, S. , and Cadou, C. , 2013, “ Scaling of Miniature Piston-Engine Performance—Part 2: Energy Losses,” J. Propul. Power, 29(4), pp. 88–799.
Ausserer, J. K. , Polanka, M. D. , Litke, P. J. , Grinstead, K. D. , and Baranski, J. A. , 2017, “ Measurement of Loss Pathways in Small, Two-Stroke Internal-Combustion Engines,” SAE Int. J. Engines, 10(2), pp. 128–143. [CrossRef]
Drela, M. , 2007, “ QPROP: Propeller/Windmill Analysis and Design,” accessed Apr. 6, 2017, http://web.mit.edu/drela/Public/web/qprop/
Cadou, C. , 2004, “ Scaling of Losses in Small IC Aero Engines With Engine Size,” AIAA Paper No. 2004-690.
Moulton, N. , 2007, “ Performance Measurement and Simulation of a Small Internal Combustion Engine,” M.S. thesis, University of Maryland, College Park, MA.
Cathcart, G. , and Dickson, G. , 2005, “ The Application of Air-Assist Direct Injection for Spark-Ignited Heavy Fuel 2-Stroke and 4-Stroke Engines,” SAE Paper No. 2005-32-0065.
Duddy, B. , Lee, J. , Walluk, M. , and Hallbach, D. , 2011, “ Conversion of a Spark-Ignited Aircraft Engine to JP-8 Heavy Fuel for Use in Unmanned Aerial Vehicles,” SAE Paper No. 2011-01-0145.
Romani, L. , Balduzzi, F. , and Vichi, G. , 2015, “ An Experimental Methodology for the Evaluation of the Trapped Air-Fuel Ratio of a Small 2S LPDI Engine,” SAE Paper No. 2015-32-0762.
Winkler, F. , Oswald, R. , Schögl, O. , Abis, A. , Krimplstätter, S. , and Kirchberger, R. , 2015, “ Layout and Development of a 300 Cm³ High Performance 2S-LPDI Engine,” SAE Paper No. 2015-32-0832.
Trattner, A. , Grassberger, H. , Schoegl, O. , Schmidt, S. , Kirchberger, R. , Eichlseder, H. , Kölmel, A. , Meyer, S. , and Gegg, T. , 2014, “ Advantages and Challenges of Lean Operation of Two-Stroke Engines for Hand-Held Power Tools,” SAE Paper No. 2014-32-0009.
Sher, E. , and Levinzon, D. , 2005, “ Scaling-Down of Miniature Internal Combustion Engines: Limitations and Challenges,” Heat Transfer Eng., 26(8), pp. 1–4. [CrossRef]
Sher, I. , Levinzon-Sher, D. , and Sher, E. , 2009, “ Miniaturization Limitations of HCCI Internal Combustion Engines,” Appl. Therm. Eng., 29(2–3), pp. 400–411. [CrossRef]
Sher, E. , and Sher, I. , 2011, “ Theoretical Limits of Scaling Down Internal Combustion Engines,” Chem. Eng. Sci., 66(3), pp. 260–267. [CrossRef]
Hiserote, R. M. , and Harmon, F. , 2010, “ Analysis of Hybrid-Electric Propulsion System Designs for Small Unmanned Aircraft Systems,” AIAA Paper No. 2010-6687.
Garg, M. , Kumar, D. , Syed, M. , and Nageswara, S. , 2015, “ CFD Modelling of a Two Stroke Engine to Predict and Reduce Short Circuit Losses,” SAE Paper No. 2015-32-0702.
Mataczynski, M. , Hoke, J. , Paxson, D. , and Polanka, M. D. , 2014, “ Design, Simulation, and Testing of a Pressure Wave Supercharger for a Small Internal Combustion Engine,” SAE Paper No. 2014-01-2136.
Ausserer, J. K. , Horn, K. P. , Polanka, M. D. , and Litke, P. J. , 2015, “ Quantification of Short-Circuiting and Trapping Efficiency in a Small Internal Combustion Engine by GC-MS and GC-TCD,” SAE Paper No. 2015-32-0716.
Ausserer, J. K. , Litke, P. J. , Groenewegen, J. R. , Rowton, A. , and Polanka, M. , 2013, “ Development of Test Bench and Characterization of Performance in Small Internal Combustion Engines,” SAE Paper No. 2013-32-9036.
Ausserer, J. K. , Rowton, A. , Litke, P. , Grinstead, K. , and Polanka, M. , 2014, “ Comparison of In-Cylinder Pressure Measurement Methods in a Small Spark Ignition Engine,” SAE Paper No. 2014-32-0007.
Horn, K. P. , Rowton, A. K. , Polanka, M. D. , Ausserer, J. , Litke, P. J. , and Grinstead, K. D. , 2015, “ Dynamic Friction Measurements on a Small Engine Test Bench,” AIAA Paper No. 2015-1474.
Baranski, J. , 2013, “ Experimental Investigation of Octane Requirement in a Turbocharged Spark-Ignition Engine,” M.S. thesis, University of Dayton, Dayton, OH.
Ausserer, J. K. , 2016, “ The Scaling of Loss Mechanisms and Heat Transfer in Small Scale Internal Combustion Engines,” Ph.D. dissertation, Air Force Institute of Technology, Wright-Patterson AFB, OH.
Pádua, A. A. H. , Fareleira, J. M. N. A. , and Caldo, J. C. G. , 1996, “ Density and Viscosity Measurements of 2,2,4-Trimethylpentane (Isooctane) From 198K to 348K and Up to 100 MPa,” J. Chem. Eng. Data, 41(6), pp. 1488–1494. [CrossRef]
Pecar, D. , and Dolecek, V. , 2007, “ Temperature and Pressure Dependence of Volumetric Properties for Binary Mixtures of n-Heptane and n-Octane,” Acta Chim. Solvenica, 54(3), pp. 538–544.
SAE International, 2011, “ Surface Vehicle Information Report: Instrumentation and Techniques for Exhaust Gas Emissions Measurements,” SAE International, Warrendale, PA, Standard No. J254.
Blair, G. P. , 1996, Design and Simulation of Two-Stroke Engines, Society of Automotive Engineers, Warrendale, PA. [CrossRef]
Zhao, H. , and Ladommatos, N. , 2001, Engine Combustion and Diagnostic, Society of Automotive Engineers, Warrendale, PA. [CrossRef]
Moeser, C. M. , Gantert, J. , Keck, U. , Raffenberg, M. , Rieber, M. , and Rosskamp, H. , 2006, “ Emissions and Performance Potential of a Small Stratified Charge 2-Stroke Engine Using Reed Valves,” SAE Paper No. 2006-32-0058.
Bergman, M. , Enander, N. , and Lawenius, M. , 2013, “ CFD Scavenging Simulation and Verification of a Sequentially Stratified Charged Two-Stroke Engine,” SAE Paper No. 2013-32-079.
Davidson, D. F. , Oehlschlaeger, M. A. , and Hanson, R. K. , 2007, “ Methyl Concentration Time-Histories During Iso-Octane and n-Heptane Oxidation and Pyrolysis,” Proc. Combust. Inst., 31(1), pp. 321–328. [CrossRef]

Figures

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Fig. 1

SERB schematic showing fluid-flow pathways and measurement equipment

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Fig. 2

SERB exhaust system schematic showing sampling-port location. Diagram is not drawn to scale.

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Fig. 3

Effect of rotational speed on energy pathways and balances

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Fig. 4

Effect of engine rotational speed on (a) fuel-conversion efficiency and (b) IMEP

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Fig. 5

Effect of equivalence ratio on (a) fuel-conversion efficiency and (b) IMEP

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Fig. 6

Effect of equivalence ratio on energy pathways and balances

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Fig. 7

Effect of combustion-phasing on (a) fuel-conversion efficiency and (b) IMEP

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Fig. 8

Effect of combustion phasing on energy pathways

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Fig. 9

Effect of combustion phasing on measured emissions

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Fig. 10

Effect of combustion phasing on EGT

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Fig. 11

Effect of cooling-air speed on engine head temperature

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Fig. 12

Effect of cooling-air speed on engine cooling load

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Fig. 13

Effect of cooling-air speed on (a) fuel-conversion efficiency and (b) engine power

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Fig. 14

Effect of cooling-air speed on energy pathways

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Fig. 15

Effect of delivery ratio (throttle) on (a) fuel-conversion efficiency and (b) engine power

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Fig. 16

Effect of delivery ratio (throttle) on energy pathways and balances

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Fig. 17

Effect of delivery ratio (throttle) on charging and trapping efficiencies

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Fig. 18

Effect of delivery ratio (throttle) on trapped-energy pathways and balances

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