A. C. Alkidas

An experimental investigation of surface thermometry and heat flux

Abstract Several types of surface-temperature sensors were characterized in terms of the thermal properties of their substrates and their response times. This was followed by an evaluation of their capabilities as transient heat flux sensors using a rapid-compression machine. The thermal properties of the sensor substrate were found to affect significantly the measured heat flux, and therefore a mismatch in the thermal properties of the sensor and the test-section walls may cause erroneous results.

Combustion Characteristics of a Spray-Guided Direct-Injection Stratified-Charge Engine with a High-Squish Piston

This work describes an experimental investigation on the stratified combustion and engine-out emissions characteristics of a single-cylinder, spark-ignition, direct-injection, spray-guided engine employing an outward-opening injector, an optimized high-squish, bowled piston, and a variable swirl valve control. Experiments were performed using two different outward-opening injectors with 80° and 90° spray angles, each having a variable injector pintle-lift control allowing different rates of injection. The fuel consumption of the engine was found to improve with decreasing air-swirl motion, increasing spark-plug length, increasing spark energy, and decreasing effective rate of injection, but to be relatively insensitive to fuel-rail pressure in the range of 10-20 MPa. At optimal injection and ignition timings, no misfires were observed in 30,000 consecutive cycles. Multiple pulsing of the injector did not improve upon the single injection-pulse results either by changing the timing of the injection process or by changing the dwell time between injection events.

A visual study of divided-chamber diesel combustion using a rapid compression machine

Abstract The processes of air introduction, fuel injection, ignition, and combustion are investigated optically in simulated diesel engine prechambers mounted on a rapid compression machine. During the compression stroke air velocities at the edge and center of one of the prechambers are on the order of 20 and 15 m/s, respectively. The airflow, therefore, is more complex than solid-body rotation. During fuel injection the fuel spray is strongly deflected by the airflow and hits the glow plug and the wall opposite the injector. Fuel evaporation and air-fuel mixing begin 0.3–0.5 ms after the start of injection but are not complete within the ignition delay period (1–1.5 ms). Hence ignition and combustion occur at times when both liquid and gaseous fuel exist in the prechamber. This liquid fuel is located both within the volume and on the surfaces of the prechamber. Combustion is strongly luminous and implies significant soot formation in the prechamber.

On the performance and emissions of an uncooled heavy-duty single-cylinder diesel engine

In this study the performance and emissions of an uncooled 2.0-L single-cylinder open-chamber diesel engine were experimentally investigated further. In addition to the routine performance and emissions measurements, the heat-release characteristics, friction losses, and temperatures of combustion-chamber components were measured

A Two-Stage Heat-Release Model for Diesel Engines

Modele de calcul du degagement de chaleur dans un moteur diesel considerant deux phases dans la combustion