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A carbon-fiber-reinforced plastic (CFRP) monocoque racecar frame was designed and constructed by students for the 2012 Formula SAE (FSAE) collegiate design series competition. FSAE rules require that the monocoque frame have strength equal to or greater than the traditional steel space frames that they replace. The rules also specify minimum values for perimeter shear strength, main roll hoop attachment strength and driver harness attachment (pullout) strength. Overcoming limitations imposed by locally available finite element analysis tools, a variety of tests were devised to determine required laminate thicknesses and layup orientations. These included perimeter shear tests, pin shear tests, three-point bend tests and tensile tests. Based on the results of these tests, a sandwich construction using composite skins fabricated from carbon/epoxy prepreg and aluminum honeycomb core was selected.

Synthetic diesel fuels from Fischer-Tropsch or hydrotreating processes have high cetane numbers with respect to conventional diesel fuel. This study investigates diesel combustion characteristics with these high cetane fuels. A military jet fuel (JP-5 specification), a Fischer-Tropsch (FT) synthetic diesel, and normal hexadecane (C16), a pure component fuel with defined cetane number of 100, are compared with operation of conventional military diesel fuel (F-76 specification). The fuels are tested in a AM General GEP HMMWV engine, an indirect-injection, largely mechanically-controlled diesel engine. Hundreds of thousands of these are in current use and are projected to be in service for many years to come. Experimental testing showed that satisfactory operation could be achieved across the speed-load operating map even for the highest cetane fuel (normal hexadecane). The JP-5, FT, and C16 fuels all showed later injection timing.

Due to their high specific stiffness and strength, carbon-epoxy composites have become the predominant structural material at the highest levels of international motorsport and are also gaining widespread popularity in collegiate design competitions. Formula SAE is one such event where college students design, build, and race a small, formula-style race car in an autocross environment. The use of composite materials in the structure of these vehicles provides a competitive advantage through weight reduction. Undergraduate students often face a steep learning curve when dealing with composite materials, however, as they have had little exposure to the design, analysis, and fabrication processes of composite structures. By outlining the design and testing of a carbon-epoxy A-arm for a Formula SAE vehicle, this paper will serve as an introduction to the unique benefits and challenges associated with composite motorsports structures.

Future synthetic diesel fuels will likely involve mixtures of straight and branched alkanes, possibly with aromatic additives to improve lubricity and durability. To simulate these future fuels, this study examined the combustion characteristics of binary mixtures of 50%, 70%, and 90% isododecane in hexadecane, and of 50%, 70%, and 80% toluene in hexadecane using a single-cylinder research diesel engine with variable injection timing. These binary blends were also compared to operation with commercial petroleum diesel fuel, military petroleum jet fuel, and five current synthetic Fischer-Tropsch diesel and jet fuels. The synthetic diesel and jet fuels showed reasonable similarity with many of the combustion metrics to mid-range blends of isododecane in hexadecane. Stable diesel combustion was possible even with the 80% toluene and 90% isododecane blends; in fact, operation with 100% isododecane was achieved, although with significantly advanced injection timing.

This study considers the relatively high fuel consumption of small-displacement Diesel engines and seeks to improve it through thin ceramic thermal barrier coatings. A small displacement (219 cc) single-cylinder direct-injection production Diesel engine is utilized. A Ricardo WAVE simulation is developed and suggests that through simultaneous application of the coatings and reduction of compression ratio, the fuel consumption can be improved through a reduction in thermal losses. At the stock compression ratio, the application of thermal barrier coatings does not improve fuel consumption unless injection timing is carefully controlled. When injection timing is also adjusted, fuel consumption can be improved by up to 10%, particularly at low loads, with application of the thermal barrier coatings. The data show higher rates of energy release, higher peak pressures, leading to the lower fuel consumption.

Single cylinder diesel engine cycle resolved startup experiments were performed at two different Compression Ratios. At CR18 (CR = 18) conventional engine starting resulted in a broad range of acceptable startup equivalence ratios (φ). However, reducing the CR to 16 resulted in problematic engine starting regardless of fuel level. In an effect to produce robust engine starting at lower CRs the engine was motored first. This allowed for strong starting performance coupled with high load fueling levels. For both CRs, IMEPg and exhaust CO2% increased as fueling level increased. However, while in-cylinder CO2% exceeded exhaust CO2% for moderate φ, this trend was reversed as fueling was reduced. Exhaust CO% was minimal except for stoichiometric fueling at CR18. Peak NOx production occurred at CR18 and φ = 0.55. Exhaust UHCs were maximized for higher fueling cases but dropped quickly after start. Similarly, ignition delay increased with φ but decreased during warm-up.

Intake tuning is a relatively simple alternative to turbochargers and superchargers as a means of augmenting engine performance. Capitalizing on air flow harmonics at specific engine speeds, intake tuning forces more air into the engine cylinders, resulting in greater torque and power. Concepts such as Helmholtz Resonance Theory and Reflective Wave Theory help to describe the physical phenomena that contribute to intake tuning, but previous studies have generally found that computer models utilizing computational fluid dynamics (CFD) are needed to accurately predict performance effects. The current research involves testing various intake runner lengths and cross section geometries on a Honda CBR600 F4i gasoline engine typically used to power a Formula SAE car. Also, the effect of adding 180 degree bends to intake runners is evaluated.

Fast emissions analysis, soot analysis, and pressure sensing is utilized to examine the first few seconds before, and after startup in a single-cylinder CFR diesel engine. The equivalence ratio, compression ratio, and injection timing are varied. The data show that UHC and CO emissions are highest at the highest and lowest fueling conditions, while NOx emissions peaked at intermediate fueling conditions. Leaner operating conditions show delayed starting but reduced ignition delay. Oil vapor causes soot emissions prior to first combustion, and soot particle size shifts higher during the first few seconds after combustion begins. Injection timing has little effect except at the leanest equivalence ratios, where a retarded injection timing increases the delay until a successful combustion event. At lower compression ratios, large IMEP oscillations occurred during startup. The data suggest possible strategies to optimize diesel startup.

Intake tuning is a widely recognized method for optimizing the performance of a naturally aspirated engine for motorsports applications. Wave resonance and Helmholtz theories are useful for predicting the impact of intake runner length on engine performance. However, there is very little information in the literature regarding the effects of intake plenum volume. The goal of this study was to determine the effects of intake plenum volume on engine performance for a restricted naturally aspirated engine for Formula SAE (FSAE) vehicle use. Testing was conducted on a four cylinder 600 cc motorcycle engine fitted with a 20 mm restrictor in compliance with FSAE competition rules. Plenum sizes were varied from 2 to 10 times engine displacement (1.2 to 6.0 L) and engine speeds were varied from 3,000 to 12,500 RPM. Performance metrics including volumetric efficiency, torque and power were recorded at steady state conditions.

Fischer-Tropsch (FT) synthetic fuels have been shown to produce lower soot and oxides of nitrogen emissions than petroleum-based diesel #2 (D2) in previous studies. This performance is frequently attributed to the very low aromatic content as well as essentially zero sulfur content. The objective of this empirical study was to investigate the high engine load regime using a military FT and D2 fuel in a CFR diesel engine at fueling levels approaching stoichiometric. A testing matrix comprised of various injection advance set points, fueling amounts (e.g. load) above 6 bar gross indicated mean effective pressure (IMEPg), and three different compression ratios (CR) was pursued. The results show that oxides of nitrogen emissions are always equal to or lower running FT compared to diesel. This result is attributed to the higher cetane number of FT leading to lower peak in-cylinder pressures as compared to D2.

Optimization of in-cylinder air-fuel mixture preparation in Port Fuel Injected (PFI) engines during all phases of operation is critical for maximizing engine performance while minimizing harmful emissions. In this study, a Cooperative Fuels Research (CFR) gasoline engine is used to evaluate torque and measure in-cylinder and exhaust CO, CO2 and unburned hydrocarbons under various fueling and spark conditions during crank and startup phases. Fast Flame Ionization Detectors (FFID) and Non-Dispersive Infra-Red (NDIR) fast CO and CO2 detectors are used as the principle diagnostics. Additionally, detailed cycle resolved fuel accounting is performed to elucidate the fuel vaporization process from injection to exhaust. The majority of liquid fuel accumulation in the engine puddles occurs within 3 engine cycles after cranking begins. Post combustion UHCs were seen to reach levels of 40-80% of pre-combustion UHC values.

Ethanol based fuels have seen increased use in recent years due to their renewable nature as well as increased governmental regulatory mandates. While offering performance advantages over gasoline, especially at high compression ratios, these fuels are more sensitive to pre-ignition (PI). Pre-ignition experiments using ethanol (E100) and E85 were performed in a CFR spark ignition engine using a diesel glow plug “hot spot” to induce PI. PI is found to occur over a specific air-fuel ratio range based on hot spot temperature. Additionally, increasing ethanol content or compression ratio (CR) decreases glow plug temperature thresholds for PI. A kinetics-based model was used to simulate pre-ignition of E100 and to elucidate sensitivities of pre-ignition to various operating parameters, including initial charge temperature, air dilution, and residual dilution. The model shows that the most violent cases of PI can be mitigated by switching to either lean or rich operation.

Seven biofuel-diesel fuel configurations were tested in a single-cylinder research diesel CFR engine that allowed variable injection timing. These seven configurations included three biodiesel-diesel blends (20% and 100%); two ethanol-diesel blends (15% and 20%), and two cases in which ethanol was injected into the intake air flow (20% and 33%). Combustion characteristics, NOx emissions, and soot emissions were compared with diesel operation across a range of injection timings. The effect of fuel compressibility affected the timing of injection, with biodiesel-diesel blends having advanced injection and ethanol-diesel blends having delayed injection. Biodiesel-diesel blends showed reduced ignition delay with only modest changes in combustion duration, while ethanol-diesel mixtures showed longer ignition delay but much shorter combustion duration and earlier phasing.

In the near future increasing use of ethanol in motor fuels will occur due to legislative mandates. E10 (Gasohol) and E85 will see more widespread use in spark ignition engines. This study looks at the performance and knock characteristics of E10 and E85 in comparison to regular gasoline. Detailed experimental engine data and analysis as a function of compression ratio, ignition timing and fueling are presented with associated physical explanations. Comparative results are presented. Increasing ethanol content provides for greater engine torque, efficiency and knock tolerance, yet fuel consumption worsens. Knock limited trends and sensitivities are presented, for example, 5 degrees of spark retard are required with E10 and gasoline for each compression ratio increase, while the much less sensitive E85 requires only 2 degrees of retard for each compression ratio increase. Trends with efficiency and torque are described amongst the fuels tested.

Internal combustion engine knock has limited compression ratios of spark ignition engines for most of the history of gasoline engines. This limitation continues to exist today. While knock is generally a low engine speed, high load phenomenon, this operating condition is infrequently used by many vehicle operators, and if the engine is brought to this operating condition generally little time is spent in this knock prone condition. This study seeks to investigate the transition into knock due to throttle changes from part to full load. The experimental results using a CFR engine operating on iso-octane fuel show that knock is delayed by at least one high load engine cycle after the throttle is opened. Optimization of spark timing to account for this effect provides for the best increase of engine load without audible knock occurring.

Bench fuel injection experiments were performed to investigate the levels of generated fuel vapor immediately after fuel injection into a closed vessel. A synthetic fuel mixture was used consisting of six individual fuel components that are representative of gasoline. Vessel (e.g. port) temperature and pressure were varied, as well as sample location and sample delay time after injection. Vessel vapor space samples were collected and processed in a gas chromatograph in order to quantify the contribution to the fuel vapor by the various fuel components. Companion modeling was performed in order to evaluate two fuel vapor mixture preparation models (Raoult's Law and NIST's SUPERTRAPP). Results indicate that approximately 1/6 to 1/3 of the injected fuel mass is in the vapor form immediately after fuel injection (as a function of temperature). SUPERTRAPP modeling indicates that the injected fuel mass is approximately in equilibrium with 6% of the available air.