Effect of Intake Manifold Geometry on Cylinder-to-Cylinder Variation and Tumble Enhancement in Gasoline Direct Injection Engine

In order to improve the performance of the gasoline direct injection engine system, it is fundamentally important to reduce the cylinder-to-cylinder variation which affected by the intake manifold geometry. Furthermore, the early tumble development which influences the characteristics of the mixture as followed by the atomization and evaporation of the fuel, also greatly affects engine performance. Thus, in this study, the cylinder-to-cylinder variation in volumetric efficiency and tumble for two different type of intake manifold (curved type and straight type) was investigated using computational fluid dynamic program, CONVERE v2.4. And influence of the intake manifold curve radius to the early flow intensity and tumble development was analyzed. As a result, it was advantageous for cylinder-to-cylinder variation in the straight intake manifold compared to the curved intake manifold. When the intake manifold curve radius was increased in the straight intake manifold, it was effective in strengthening the early flow and tumble intensity. At 3000 rpm, the distance from the intake manifold inlet to the port also had an effect. Therefore, it is possible to improve the intake manifold performance by increasing the intake manifold curve radius and adapting turbocharging at engine speeds above 3000 rpm.

QVR: Quranic Verses Recitation Recognition System using PocketSphinx

The recitation of Quran verses according to the actual tajweed is obligatory and it must be accurate and precise in pronunciation. Hence, it should always be reviewed by an expert on the recitation of the Quran. Through the latest technology, this recitation review can be implemented through an application system and it is most appropriate in this current Covid-19 pandemic situation where system application online is deemed to be developed. In this empirical study, a recognition system so-called the Quranic Verse Recitation Recognition (QVR) system using PocketSphinx to convert the Quranic verse from Arabic sound to Roman text and determine the accuracy of reciters, has been developed. The Graphical User Interface (GUI) of the system with a user-friendly environment was designed using Microsoft Visual Basic 6 in an Ubuntu platform. A verse of surah al-Ikhlas has been chosen in this study and the data were collected by recording 855 audios as training data recorded by professional reciters. Another 105 audios were collected as testing data, to test the accuracy of the system. The results indicate that the system obtained a 100% accuracy with a 0.00% of word error rate (WER) for both training and testing data of the said audios via Quran Roman text. The system with automatic speech recognition (ASR) engine system demonstrates that it has been successfully designed and developed, and is significant to be extended further. Added, it will be improved with the addition of other Quran surahs.

Integral Design of a Turbocharger for Internal Engine Energy Saving: Centrifugal Compressor Design

Energy savings and emission reductions are essential for internal engines. Turbocharger is critical for engine system performance and emission. In this study, the engine simulation program was used to systematically optimize the engine turbocharger system performance. The velocity ratio concept was used in the engine simulation program to consider the performance impacts of the wheel diameter ratio between compressor and turbine. An integral consideration for both compressor and turbine was proposed to design the new turbocharger. An optimization process was used to design the compressor. The final designs employed Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) solvers for the performance and mechanical integrity assessments. The optimized compressor wheel has different features comparing with conventional designs. In this design, the splitter is not located in the middle between main blades; the compressor wheel exit diameter at shroud is larger than hub. The new compressor was tested on both gas stand and engine. The numerical results are fairly agreed with gas stand tests. The tests showed about 1.2% of the engine BSFC reduction without sacrifice the emission and cost. This study demonstrated that a systematic method in simulation and an integral compress design process could optimize the engine system and improve the engine performance.