Experimental Study On Hydraulic Characteristics Of Tooth Block Energy Dissiption

Along with the high dam construction in our country, the problem of energy dissipation in the high water head outlet structure is becoming more and more attention by the people. The internal energy dissipater as a new way of energy dissipation. It has the efficiency effect of energy dissipation,a variety of size selection and powerful protection for the ecological environment, It is worth to continuously explore and in-depth research. In order to reduce the effect of the size and shape of energy dissipater on the flow capacity. Based on plug energy dissipater research findings, a new type of tooth block energy dissipater is put forward.On changing the number of tooth block and the area contraction ratio,eight different experiment scheme are developed. Through physical model test and theoretical analysis, we have preliminary explored the energy dissipation characteristic and the fluctuating pressure characteristic of the tooth block energy dissipater. The main conclusions can be listed as follows:1. The head loss of the tooth block energy dissipater consists of two parts, one part is caused by the sudden enlargement and the shrinkage of local head loss, the other part is the frictional head loss.2. After analysis different scheme’s time average pressure,the research results show that time average pressure distribution are basically same and decreasing rapidly in the inlet. The minimum appear in outlet and then gradually recover smoothly. The more the area contraction ratio, the greater the pressure steady position is.3. Based on studying the flow coefficient of the different program, analyses the main factors that affect tooth internal energy dissipater’s flow capacity. The relationship between the area contraction ratio and flow coefficient are work out. The results show that the area contraction ratio are the main factors influencing the flow capacity, under the same tooth block number, the smaller the area contraction ratio, the smaller the flow capacity is; Under the condition of the same area contraction ratio same, the flow capacity reduce when the number of tooth block are increased.4. It is concluded that the relationship between the area contraction ratio and head loss coefficient through analysis. The greater the area contraction ratio, the smaller the head loss coefficient is, and the poorer the energy dissipation effect; Under the condition of the same area contraction ratio, the number of the tooth block are increased to enhance the effect of energy dissipation. The reynolds number has no impact on the head loss coefficient.5. Through analysis the characteristics of the fluctuating pressure the result shows that the fluctuating pressure distribution of different scheme are the same, the maximum pulsating pressure points appear in nearly outlet, then gradual attenuation and steady; The bigger the area contraction ratio, the greater the pulsating pressure; Under the condition of the same area contraction ratio, the pulse pressure of size Ⅰ is greater than the size Ⅱ, which suggests that increased number of tooth block help weaken the pulsating pressure; The fluctuating pressure of each scheme are not completely according to the normal distribution, but degree of deviation is not great.6. In the test range, energy dissipation ratio of the tooth block internal energy dissipater can reach75%and eliminate a large number of redundantly energy in conduits. It is a kind of effective energy dissipation type.