Low-Cost Improvements of an Old Flow Bench and a Discussion of Replacing Orifice Plate by MAF in its Flow Measurement

Recognizing the significant challenges inherent in the analysis of periodic gas flow through reciprocating engines, one can easily appreciate the value of studying the steady flow through cylinder heads, manifolds, and exhaust systems. In these studies, flow benches are the cornerstone of the experimental apparatus needed to validate theoretical results or to perform purely experimental analysis. The Metal-Mechanics Department of IFSC owns a SuperFlow model SF-110 flow bench that has suffered some in house maintenance and received electronic sensors to allow computerized data acquisition. As the essential original sensors in this flow bench were liquid column manometer (for pressure difference across the test subject) and micromanometer (for pressure difference across the orifice plate used to measure the flow), the essential new sensors are electronic differential pressure sensors (installed in parallel with the original ones). In recent decades, however, the use of a mass air flow (MAF) sensor replacing the orifice plate and micromanometer, has been proposed in do it yourself (DIY) flow bench projects presented at the Internet. Some tests of a MAF sensor in the IFSC flow bench are being undertaken to support a discussion of its advantages and disadvantages when compared to the orifice plate. The present work discusses this substitution, as well the electronics and software used in the present version of the in house developed computerized data acquisition system. Preliminary results, difficulties and reliability issues faced by the authors in this development are discussed to share the lessons learned with the readers. The preliminary results presentation also ensues some discussion of the plethora of conflicting definitions and hypotheses that frequently make the flow bench results much more difficult to interpret than they should be.