Comparative Studies On Flow Measurement Methods For Cylinder Water Hole In Engines

Three-dimensional cooling water flow inside the cylinder is significant to engine cooling effect research, while the cooling water flow of cylinder water hole is an important indicator to characterize cylinder internal flow conditions. Therefore the ability to accurately measure cylinder water hole flow rates is significant to overall engine flow&heat transfer research. Recently there are many flow measurement methods both in domestic and abroad research area; however, little research was focused on the effect comparison of different measurement methods and the impact on the original flow field due to flowmeter installation. Therefore, in order to analyze the practical application effect of various measurement methods, several common water hole flow measurement methods were chosen to compare and analyze. Several simulation and experimental studies (outside the real body) were conducted in this thesis, also combined with real machine measurement experiment. The following works and conclusions were completed in this thesis:1. Summarized and finished the analysis of internal combustion engine water hole common flow measurement methods. Combined with the enterprise measurement and simulation data of specified research subject (Six-cylinder diesel engine), several measurement methods were chosen to operate comparative experiments (outside the real body), along with relevant principle and structure elaborations.2. An accuracy simulation test bench (outside the real body) was established. Flow rate measurement comparison tests were conducted while the pipe flow rate and diameter changed separately as test parameters; the results showed that the measurement error of each flowmeter increases with the reduction of pipe flow rate&diameter. The electromagnetic flowmeter and turbine flowmeter has relatively small average error over the entire flow range. The error of electromagnetic and orifice plate flowmeter increases obviously when the diameter reduced, while their average error even more than5%when the pipe diameter is6mm. 3. A flow field effect simulation test bench (outside the real body) was established while the pressure loss increase after flowmeter installation was used to quantify the flow field effects. Pressure loss measurement comparison tests were conducted while the pipe flow rate and diameter changed separately as test parameters; the results showed that the pressure loss of each flowmeter increases with the increase of pipe flow rate, approximately followed by linear of index trend. The pressure loss of electromagnetic flowmeter and turbine flowmeter are relatively small while the orifice plate flowmeter has the highest rate. With the decreasing of pipe diameter, the pressure loss sequence of all flowmeters is basically orifice plate type> pitot tube type> turbine type> electromagnetic type.4. A real machine flow measurement test bench was established. According to simulation test results, the turbine flowmeter was chosen to measure the actual machine cylinder water hole flow rate. The measurement results was compared to standard values obtained through multiple repetitive tests and showed that the maximum flow measurement relative error was lower than2.5%and the average relative error was basically1.5%. Combined with simulation test results, this result was considered to be able to meet engineering application requirements. Given that the real machine cylinder water hole pressure loss is very difficult to measure, the analyze process was conducted by numerical simulation; the results showed that the magnitude of water hole flow rate change is no more than1.0%while the flow conditions inside each water hole basically remain unaffected.