Study On Test Method Of Steady Flow Test Of Engine

In the internal combustion(IC) engine, the air flow determined by the intake ports in thecylinder directly affects the combustion characteristics, thereby affecting the engine power,economy and emissions. It is an efficient and widely used method to develop IC engine thatevaluating the ports by the flow parameters such as flow coefficient, swirl ratio, tumble ratioacquired by the steady flow test rig. Nowadays, there are several evaluation method of steadyflow including Ricardo, FEV, AVL and SwRI methods, but not a full and fair standard, especiallyfor the tumble test and evaluation.In view of the above, the different tumble evaluation methods were studied through thesteady flow test by the optical FEV tumble test rig and different experimental cylinders. And themicro-structure of the flow fields in the optical cylinders was studied by the particle imagevelocimetry(PIV) to understand the difference of the test methods, in order to acquire theuniform tumble test method conductive to guide the development and performance evaluation ofports.Experimental studies have shown it is the same that the flow coefficient obtained fromdifferent tumble testing and evaluation methods essentially. However, there is a jump for tumblestrength measurements with FEV method at a certain valve lift condition and the measurementsare relatively larger, compared with other measurement methods. It can be seen from the PIVflow fields that the reason for the jump is the measured tumble not steadied by the guide pipe, soflow structure mutation exists at a certain valve lift condition; and there are two reasons for thelarger measurement result of FEV tumble strength, one is compared with other methods, tumblehas not been weaken by the guide pipe; the other is the strengthened tumble by the small outletdiameter of cylinder.The FEV tumble strength (ie speed of tumble rotating) is lower at the symmetry plane of thecylinder, and basically does not change with the outlet diameter of the cylinder; but tumblestrength is higher at its outlet, and increases with the outlet decreased; when the outlet diameter is greater than 0.7D, the tumble strength at the outlet even less than the one at the symmetryplane.The large pressure drop exists in the FEV tumble test device, which is directly related tooutlet diameter of cylinder, and increases with the decrease of the outlet diameter, and pressuredrop is more severe at higher valve lift conditions.