Detects the flow of cooling water in the engine

The flow of cooling water is 135.31Lmin. The two-dimensional measurement of the flow velocity in the horizontal direction of the cylinder head cooling water is performed by a laser. The computer automatically processes the measurement result. The test tests the speed in the six horizontal planes in the cylinder head and measures the result. The location of the section. In Fig. 3, the topmost surface is located 7mm from the top cut surface, and other surfaces become deeper with the serial number. The distribution of cooling water flow paths in a representative cross-section in the cylinder head water chamber is shown.

As a result, the cooling water in the cylinder head flows from the fourth cylinder to the first cylinder, and then the cooling water flows back to the cooling water tank. The cooling water flow in the cylinder head is of course three-dimensional. The cooling water enters the cylinder head from the cylinder, and the vertical flow to the upper wall eventually becomes a horizontal flow and flows out of the first cylinder. Therefore, if carefully measured The speed in the horizontal plane can grasp the main characteristics of the cooling water flow in the cylinder head. On the other hand, the flow of cooling water is almost turbulent, and the laser measured flow rate is the average value within a certain period of time. It is generally believed that turbulence reduces the speed boundary layer compared to laminar flow and has a good effect on the cooling of the cylinder head. As can be seen from FIG. 5, the cooling water flow rate in the horizontal plane gradually increases from the fourth cylinder to the first cylinder. The downstream first cylinder not only receives the cooling water from the cylinder but also receives the flow from the upstream. Cooling water. Therefore, the downstream cylinder head is cooled better than the upstream cylinder head.

Because the heat load of the exhaust valve and exhaust port is higher than that of the suction side, special attention is required. The water from the cooling water tank enters the cylinder through the cooling water pump, first cooling the cylinder block, and then entering the intake and exhaust side of the cylinder head. As shown, five parts of the water from the cylinder block flow downstream: 1 through the cooling channel between the exhaust passage and the combustion chamber; 2 between the intake and exhaust valve cooling channels; 3 inlet and combustion chambers Between the cooling water channel; 4 test diesel engine for the four valve overhead type structure, cooling water flows through the cooling water channel around the injection; 5 above the exhaust channel cooling water channel, the above number corresponds to the number of the label. Considering the above factors, most of the cooling water in the vertical direction flows through the bottom of the cylinder head near the combustion chamber, and more cooling water in the horizontal direction flows through the side of the exhaust gas. This will cool the area with high heat load.

From the flow point of view, the cooling conditions of the corresponding cylinder head portions of the cylinders on the cooling water swim are more severe than the cooling conditions of the corresponding cylinder head portions of the downstream cylinders, and the cooling water flow in the upstream part of the cylinder head must be reasonably distributed and ensured enough. The amount of cooling water. The downstream cylinder head has the same shape as the upper waterway, and the cooling effect is better. From the perspective of the velocity distribution in the vertical direction, the flow rate tends to become smaller as it goes downwards, but the change is slower, and the flow rate increases again near the bottom surface. This is obvious. This indicates that the flow velocity distribution in the vertical direction is good, and the cooling water flows through the bottom of the cylinder head cooling water chamber at a greater speed. The top of the combustion chamber and the exhaust passage are well cooled. If the cooling water flow rate in the lower region is too small compared with the upper and middle regions, it means that the flow resistance in the lower region is too large, and the cooling water flows too much from the upper middle portion, which is not conducive to the cooling of the cylinder head. In addition, the flow of cooling water in the closed end of the cylinder head corresponding to the fourth cylinder is relatively special, where the space is particularly narrow, and the vertical flow of the cooling water is relatively obvious.

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