Abstract: In measuring the flow through the water holes on the upper surface of cylinder block in a diesel engine, the measurement module composed of turbine flowmeter and measuring plates may cause pressure loss in cooling water flow, hence affecting the accuracy of measurement results. In order to study the influence of the measurement module on the flow measurement, test and simulation are carried out in this paper. Firstly, the flow measurement is conducted by using turbine flowmeter and a measuring plate. Then, a 3D CFD simulation is performed on the flow of cooling system with an outcome indicating that the measurement module has a relatively great effect on the results of water flow measurement, with a maximum relative error more than 25%. On the basis of this, the influences of the inner diameter and length of the turbine flowmeter and the water hole structure, hole diameter and depth of the measuring plates on flow measurement are analyzed. Finally, an optimally matched measurement module is obtained, consisting of a turbine flowmeter with an inner diameter of 15mm, a length of 55mm and a measuring plate with a depth of 20mm, a water outlet diameter of 15mm and a cylindrical structure of water hole. The results show that the modified measurement module can effectively improve the accuracy of water flow measurement, with a maximum relative error of only 3.60%.

Key words: upper water hole on cylinder block, flow measurement, turbine flowmeter, measurement module, test, simulation