Nasa Tm X-73500 Emissions of an Avco Lycoming 0-320-Diad
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NASA TECHNICAL NASA TM X-73500 MEMORANDUM C (NASA-TM-X-73500)- EMISSIONS OF AN AVCO N77-10058 < LYCOMING 0-320-DIAD AIR COOLED LIGHT <O AIRCRAFT ENGINE AS A FUNCTION OF FUEL-AIR C RATIO, TIMING, AND AIR TEMPERATURE AND Unclas 'HUMIDITY (NASA). 206 p HC AIf0/HF A01 G3/07 08008 EMISSIONS OF AN AVCO LYCOMING 0-320-DIAD AIR COOLED LIGHT AIRCRAFT ENGINE AS AFUNCTION OF FUEL-AIR RATIO. TIMING, AND AIR TEMPERATURE AND HUMIDITY -by Philip R. Meng, Michael Skorobatckyi, Donald V. Cosgrove, and Erwin E. Kempke Lewis Research Center N Cleveland, Ohio 44135 August 1976 c 1. Report No. - 2. Government Accession No. 3. Recipient's Catalog No. NASA TM X-73500 I 4. Title and Subtitle EMISSIONS OF AN AVCO LYCOMING O-320-DIAD 5 Report Date AIR COOLED LIGHT AIRCRAFT ENGINE AS A FUNCTION OF August 1976 FUEL-AIR RATIO, TIMING, AND AIR TEMPERATURE AND 6 Performing Organization Code HUMIDITY 7. Author(s) 8 Performing Organization Report No. Phillip R, Meng, Michael Skorobatckyi, Donald V. Cosgrove, and Erwin E. Kempke 10. Work Unit No. 9. Performing Organization Name and Address Lewis Research Center 11. Contract or Grant No. National Aeronautics and Space Administration Cleveland, Ohio 44135 13, Type of Report and Period Covered 12. Sponsoring Agency Name and Address Technical Memorandum National Aeronautics and Space Administration 14. Sponsoring Agency Code Washington, D.C. 20546 15. Supplementary Notes 16. Abstract A carbureted aircraft engine was operated over a range of test conditions to-establish the exhaust levels over the EPA seven-mode emissions cycle. Baseline (full rich production limit) exhaust emissions at an induction air temperature of 590 F and near zero relative humidity were 90 percent of the EPA standard for HC, 35 percent for NO , and 161 percent for CO. Changes in ignition timing around the standard 250 BTDC from 300 'BTDC to 200 BTDC had little effect on the exhaust emissions. Retarding the timing to 150 BTDC in creased both the HC and CO emissions and decreased NOX emissions. HC and. CO emis sions decreased as the carburetor was leaned out, while NOx emissions increased. The EPA emission standards were marginally achieved at two leanout conditions. Variations in the quantity of cooling air flow over the engine had no effect on exhaust emissions. Temperature-humidity effects at the higher values of air temperature and relative humidity tested indicated that the HC and CO emissions increased significantly, while the NOx emis sions decreased.' 17. Key Words (Suggested by Author(s)) 18. Distribution Statement Aircraft piston engine Unclassified - unlimited Emissions Ambient effects on emissions 19. Security Classif. (of this report) 20 Security Ctassif. (of this page) 21. No. of Pages 22. Price* Unclas sifted Unclassified *For sale by the National Technical Information Service, Springfield, Viginia 22161 EMISSIONS OF AN AVCO LYCOMING 0-320-DIAD AIR COOLED LIGHT AIRCRAFT ENGINE AS A FUNCTION OF FUEL-AIR RATIO-, TIMING, AND AIR TEMPERATURE AND HUMIDITY by Phillip R. Meng, Michael Skorobatckyf, Donald V. Cosgrove, and Erwin E. Kempke Lewis Research Center SUMMARY A carburetted four-cylinder air-cooled Lycoming 0-320,DIAD aircraft engine was operated over a range of test conditions to establish the ex haust emission levels over the Environmental Protection Agency (EPA) seven-mode emissions cycle. The test program included: baseline per formance and emissions, ignition timing changes, carburetor leanout, cooling air flow variations, and temjerature-humidity effects. 00 The baseline exhaust emissions at an induction air temperature of c 590 F and near-zero relative humidity were 90 percent of the EPA standard I for hydrocarbons (HC), 35 percent of the standard for oxides of nitrogen W(NOx), and 161 percent of the standard for carbon monoxide (CO). Changes Id ignition timing around the standard 250 BTDC from 300 to 200 BTDC had little effect on the exhaust emissions. As the timing was retarded to 150 BTDC, both the HC and CO emissions increased to exceed the EPA standard while the NOx decreased slightly. The HC and CO emissions de &creaSedas the carburetor-was leaned out, while the NOx emissions in creased over a series of seven-mode cycle tests." The EPA emission stand ards were marginally achieved at two lean-out conditions where, as the engine was leaned out, the CO emissions dropped below the standard before the NOx emissions rose above the standard. Variations in the quantity of cooling air flow over the engine had essentially no effect on exhaust emissions at either of the two air temperatures tested. Temperature humidity effects at the higher values of air temperature and relative humidity indicate that the HC and CO emissions increased significantly, while the NO. emissions decrease. However, these changes in emissions were primarily the result of the richer fuel-air ratios which resulted from the decrease in air density with increased temperatures and the volume of air displaced by water vapor at the higher relative humidity. INTRODUCTION NASA is involved in a research and technology program related to general aviation engines. The overall objective of the program is to STAR category 07 2 establish and demonstrate the technology which will safely reduce general aviation piston-engine exhaust emissions to the levels required by the EPA 1979 emissions standards. One element of the above program is a joint FAA/NASA General Avia tion Piston Engine Emissions Reduction effort. Funded studies are now under way .by the two primary engine firms building general aviation piston engines, AVCO-ycoming and Teledyne - Continental. In phase I of their three-phase programs each contractor is testing five different engine models to experimentally characterize emissions and to determine the effects of variation in fuel-air ratio and spark timing on emissions levels and other operating characteristics such as cooling, misfiring, roughness, power acceleration, etc. The FAA is using its NAFEC facility to perform independent checks on each of the engines the contractors are testing in phase I. f Test results of the same engines at these different geographical locations have shown different levels of emissions and performance which make it difficult to make comparisons. Ambient temperature and humidity are known to affect test results and there are no known correlations of temperature and humidity effects. NASA-Lewis Research Center has under taken a series of aircraft engine tests to develop such a correlation. Two engines, models identical to ones in the FAA/NASA program, were se lected for testing. The engines were from two manufacturers; the first was an Avco-Lycoming model 0-320-DIAD, four-cylinder, naturally aspirated engine, and the second was a Teledyne-Continental Model TSIO-360, a six cylinder, turbocharged, fuel-injected engine. This report presents the initial performance and emissions test re sults on the Lycoming 0-320 DIAD engine as a function of fuel-air ratio, timing, and air temperature and humidity. APPARATUS AND PROCEDURE Test Facility The aircraft engine is shown sdhematically in figure 1 and photo graphically on the test stand in figure 2. The engine was coupled to a 300-hp dynamometer through a fluid coupling in the drive shaft which was located under a safety shield. Engine cooling and induction air were both supplied by a laboratory air distribution system. The cooling and induction air system, as shown in figure 3, can be controlled to deliver air to the engine over a temperature range of from 500 to 1200 F and over a range of relative humidity from 0 to 80 percent. The cooling air was directed down over the engine by an air distribution hood. This hood was the same as that which was used by the engine manufacturer in their engine testing. The engine cooling air was removed from the test cell by a high capacity, facility altitude exhaust system which had the inlet located beneath the engine. An additional cell exhaust fan was used to 3 maintain a slightly negative pressure in the test cell. This was done to vent off any combustible or toxic gases which may have been present in the test cell during engine operation. The engine exhaust was manifolded together in a standard configura tion with the emission sample probe located downstream of the manifold. The exhaust was then ducted out of the -cell through the roof as shown in was leak figure 2. Care was taken to insure that the exhaust system proof. A leak-proof system was necessary to prevent air dilution of the gas sample which would result in erroneous emission measurements. Engine description. - The 0-320-DIAD is a horizontally opposed, four cylinder, direct-drive, air-cooled engine. The engine has a bore of 5.125 inches and a stroke of 3,875 inches with the resulting total piston displacement being 319.8 cubic inches. The compression ratio is 8.50:1. The engine is rated 160 bhp at 2700 rpm and 0_.51 bsfc. Fuel metering is performed by a Marvel-Schebler MA4SPA carburetor using grade 100/130 aviation gasoline. A carburetor intake air box was used to insure uni form pressure distribution across the throat. The carburetor was cali brated for full-rich operation at the factory, typical of what might be expected as the rich limit of production engines. The carburetor, at this calibration, constituted the baseline for the engine. The fuel used was standardized reference fuel conforming to the requirements of the AST4 Committee on Aviation Reference Fuels and Certification. Ignition was supplied by a dual Bendix Magneto timed to 250 BTDC. The engine is' further described in AVCO Lycdming Specification 2283-C (ref. 1). Engine exhaust system. - There are two major areas of consideration that can affect the accuracy of emission measurements.