Estimation method for vertical inrush flow boundary loss of oversized fillet horn tube

Abstract

The invention belongs to the technical field of large-flow pressure water conveyance engineering, and particularly relates to a method for estimating vertical inrush flow boundary loss of an oversized fillet horn tube, which comprises the following steps of: firstly, calculating equivalent diffusivity according to the water flow, the inflow boundary diameter, the outflow boundary diameter and the boundary spacing of the fillet horn tube; then, on the basis of the value, the atmospheric water loss coefficient and the local diffusion loss coefficient at the outlet boundary in the vertical inrush flow process of the oversized fillet horn tube are calculated in sequence; and finally, superposing the two loss coefficients and calculating to obtain the total loss of the vertical inrush current boundary. The accurate and rapid calculation method for the vertical inrush flow boundary loss of the oversized fillet horn tube is given for the first time, and the problem that a traditional empirical formula cannot predict the boundary loss under the conditions that the Reynolds number is ultrahigh, the gravity effect is remarkable, and water and gas mixing is violent can be solved; therefore, accurate boundary conditions can be provided for transient flow field analysis and the like of a high-flow pressure water delivery system.

Description

Technical Field

[0001] The invention belongs to the technical field of large-flow pressurized water delivery engineering, and in particular relates to an estimation method for vertical surge boundary loss of an oversized rounded-corner trumpet tube. Background Art

[0002] In large-flow pressurized water transmission projects, water transmission pipelines with a diameter of more than 5m are often referred to as "super-sized" pipelines. Their outlets are rounded trumpet-shaped structures, and the outflow mode is vertical free flow against gravity. In this working mode, there is a significant hydraulic loss at the outlet boundary of the rounded trumpet pipe, which is called "flow boundary loss" in engineering. On the one hand, it includes local diffusion loss, and on the other hand, it includes atmospheric water loss. Due to the ultra-high Reynolds number (>10 7 ), significant gravity effect, and violent water-gas mixing. The traditional hydraulic loss empirical formula is no longer applicable. At present, there is a lack of an accurate and fast estimation method, which seriously restricts the development of steady-state flow assessment and transient flow field analysis in large-flow, low-head pressurized water transmission systems.

[0003] Therefore, there is an urgent need for an estimation method for the vertical surge boundary loss of super-large-sized rounded flared tubes to achieve efficient surge boundary loss calculation and provide technical guidance for large-flow pressurized water transmission projects. Summary of the invention

[0004] The object of the present invention is to provide a method for estimating the vertical surge boundary loss of an oversized rounded-corner flared tube, which is characterized by comprising the following steps:

[0005] Step 1: Input the water flow rate Q, the inlet boundary diameter D1, the outlet boundary diameter D2 and the distance H between the two boundaries of the rounded flared tube, and calculate the equivalent diffusion λ accordingly;

[0006] Step 2: Based on the equivalent diffusion λ, the atmospheric water loss coefficient ζ at the outlet boundary during the vertical flow of the super-large rounded flared tube is inversely calculated using the first equivalent relationship: A ;

[0007] Step 3: Based on the equivalent diffusion λ, the local diffusion loss coefficient ζ at the outlet boundary of the super-large rounded flare tube during vertical flow is inversely calculated using the second equivalent relationship: B ;

[0008] Step 4: The atmospheric water loss coefficient ζ A and the local diffusion loss coefficient ζ B By superposition, the total vertical surge boundary loss W of the super-large rounded flare tube is calculated according to the third relationship.

[0009] The calculation of the equivalent diffusion λ in step 1 includes:

[0010]

[0011] Where D1 is the inlet boundary diameter, D2 is the outflow boundary diameter, and H is the distance between the inlet boundary and the outflow boundary.

[0012] The first equivalent relationship in step 2 is:

[0013]

[0014] In the formula, β1 is the first empirical parameter, β2 is the second empirical parameter, β3 is the third empirical parameter, β4 is the fourth empirical parameter, β5 is the fifth empirical parameter, β6 is the sixth empirical parameter, and β7 is the seventh empirical parameter.

[0015] In the first equivalent relationship formula: the first empirical parameter β1 = 0.0028, the second empirical parameter β2 = -0.3112, the third empirical parameter β3 = 0.2333, the fourth empirical parameter β4 = -0.0542, the fifth empirical parameter β5 = -9.1, the sixth empirical parameter β6 = 1.35, and the seventh empirical parameter β7 = 2.9.

[0016] The second equivalent relationship in step 3 is:

[0017] λ+(α1+α2·ζ B )=0

[0018] Wherein, α1 is the eighth empirical parameter, and α2 is the ninth empirical parameter.

[0019] In the second equivalent relationship formula: the eighth empirical parameter α1=2.1591, the ninth empirical parameter α2=-3.0847.

[0020] The total vertical surge boundary loss W of the oversized rounded flared tube in step 4 is:

[0021]

[0022] Where g is the acceleration of gravity, π is the circumference constant, and Q is the water flow rate of the rounded horn pipe.

[0023] The beneficial effects of the present invention are:

[0024] By applying the method for estimating the boundary loss of vertical surge flow in super-large-sized rounded-corner trumpet tubes disclosed in the present invention, an accurate and fast calculation method for the boundary loss of vertical surge flow in super-large-sized rounded-corner trumpet tubes is given, which can solve the problem that the traditional empirical formula cannot predict the boundary loss under conditions such as ultra-high Reynolds number, significant gravity effect, and intense water-gas mixing, thereby providing accurate boundary conditions for transient flow field analysis of large-flow pressurized water delivery systems. For super-large-sized pressurized water delivery pipelines with a diameter of more than 5m, the boundary loss generated by the rounded-corner trumpet at the outlet end during the vertical surge flow process is accurately estimated, thereby providing accurate boundary conditions for transient flow field analysis of large-flow pressurized water delivery systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a flow chart of the method for estimating the vertical surge boundary loss of the super-large-size rounded-corner horn tube according to the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the super-large rounded horn tube of the present invention;

[0027] Figure 3 is the equivalent diffusion λ and the atmospheric water loss coefficient ζ described in the present invention A and the local diffusion loss coefficient ζ B Function relationship curve graph of . DETAILED DESCRIPTION

[0028] The present invention provides a method for estimating vertical surge boundary loss of an oversized rounded-corner horn tube, which is further described in detail below in conjunction with the accompanying drawings.

[0029] like Figure 1 The embodiment of the present invention shown discloses a method for estimating vertical surge boundary loss of an oversized rounded-corner horn tube, comprising:

[0030] Step 1: Input the water flow rate Q, the inlet boundary diameter D1, the outlet boundary diameter D2 and the distance H between the two boundaries of the rounded flared tube, and calculate the equivalent diffusion λ accordingly;

[0031] Step 2: Based on the equivalent diffusion λ, the atmospheric water loss coefficient ζ at the outlet boundary during the vertical flow of the super-large rounded flared tube is inversely calculated using the first equivalent relationship: A ;

[0032] Step 3: Based on the equivalent diffusion λ, the local diffusion loss coefficient ζ at the outlet boundary of the super-large rounded flare tube during vertical flow is inversely calculated using the second equivalent relationship: B ;

[0033] Step 4: The atmospheric water loss coefficient ζ Aand the local diffusion loss coefficient ζ B By superposition, the total vertical surge boundary loss W of the super-large rounded flare tube is calculated according to the third relationship.

[0034] like Figure 2 As shown, in this embodiment, taking a water pipeline with a diameter of 9m as an example, the flow rate Q = 180m 3 / s, inflow boundary diameter D1 = 9m, outflow boundary diameter D2 = 25m, two boundary spacing H = 15m, the estimation method of vertical surge boundary loss of super-large size rounded horn tube is implemented as follows:

[0035] Step 1: Input the water flow rate Q, the inlet boundary diameter D1, the outlet boundary diameter D2 and the distance H between the two boundaries of the rounded flared tube, and calculate the equivalent diffusion λ based on this. The expression is:

[0036]

[0037] Where D1 is the inlet boundary diameter, D2 is the outflow boundary diameter, and H is the distance between the inlet boundary and the outflow boundary.

[0038] Step 2: Based on the equivalent diffusion λ, the atmospheric water loss coefficient ζ at the outlet boundary during the vertical flow of the super-large rounded flared tube is inversely calculated using the first equivalent relationship: A .

[0039] The first equivalent relationship in step 2 is:

[0040]

[0041] In the formula, β1 is the first empirical parameter, β2 is the second empirical parameter, β3 is the third empirical parameter, β4 is the fourth empirical parameter, β5 is the fifth empirical parameter, β6 is the sixth empirical parameter, and β7 is the seventh empirical parameter.

[0042] Step 3: Based on the equivalent diffusion λ, the local diffusion loss coefficient ζ at the outlet boundary of the super-large rounded flare tube during vertical flow is inversely calculated using the second equivalent relationship: B .

[0043] The second equivalent relationship in step 3 is:

[0044] λ+(α1+α2·ζ B )=0

[0045] Wherein, α1 is the eighth empirical parameter, and α2 is the ninth empirical parameter.

[0046] Step 4: Substitute the atmospheric water loss coefficient ζ A and the local diffusion loss coefficient ζB After superposition, the total vertical surge boundary loss W of the super-large rounded flare tube is calculated according to the following formula.

[0047] The total vertical surge boundary loss W of the oversized rounded flared tube in step 4 is:

[0048]

[0049] Where g is the acceleration of gravity, π is the circumference constant, and Q is the water flow rate of the rounded horn pipe.

[0050] For the method for estimating the vertical inrush boundary loss of an oversized rounded horn provided by the present invention, in a preferred embodiment, in step 2, the atmospheric water loss coefficient ζ A The preferred calculation formula is: β1=0.0028, β2=-0.3112, β3=0.2333, β4=-0.0542, β5=-9.1, β6=1.35, β7=2.9.

[0051] For the method for estimating the vertical surge boundary loss of an oversized rounded-corner horn provided by the present invention, in a preferred embodiment, in step 3, the local diffusion loss coefficient ζ B The preferred empirical parameters in the calculation formula are: α1=2.1591, α2=-3.0847.

[0052] According to the above implementation process, we can get Figure 3 The equivalent diffusion λ and the atmospheric water loss coefficient ζ are shown A、 Local diffusion loss coefficient ζ B First, the equivalent diffusion λ is calculated as:

[0053]

[0054] Then, using the equivalent diffusion λ and the atmospheric water loss coefficient ζ A The atmospheric water loss coefficient ζ can be obtained by inverting the functional relationship between A ≈1.42. Then, using the equivalent diffusion λ and the local diffusion loss coefficient ζ B The local diffusion loss coefficient ζ can be obtained by inverting the functional relationship between B ≈0.77. Finally, the two parts of the hydraulic loss coefficients are superimposed to obtain the vertical inrush flow boundary total loss W≈0.89m of the super-large size rounded flared tube.

[0055] This embodiment originates from the Zhejiang Majinggang Drainage Project. Through engineering empirical analysis, it is found that the total loss of the surge boundary is about 0.85m. Obviously, the relative error between the prediction result of this patent and the true value is about 4.7%, which fully meets the engineering accuracy requirements. In contrast, the 0.31m calculated by the traditional empirical formula for hydraulic loss of diffuser pipes is quite different from the true value, and it is difficult to accurately predict the boundary loss under such working conditions. In particular, it is difficult to consider the atmospheric water loss, which significantly dominates the total loss. Therefore, this patent provides for the first time an accurate and fast calculation method for the vertical surge boundary loss of an oversized rounded trumpet pipe, which can solve the problem that the traditional empirical formula cannot predict the boundary loss under conditions such as ultra-high Reynolds number, significant gravity effect, and intense water-gas mixing, thereby providing accurate boundary conditions for transient flow field analysis of large-flow pressurized water supply systems.

Claims

1. A method for estimating vertical surge boundary loss of an oversized rounded flared tube, characterized in that: The steps include: Step 1: Input the water flow rate Q, the inlet boundary diameter D1, the outlet boundary diameter D2 and the distance H between the two boundaries of the rounded flared tube, and calculate the equivalent diffusion λ accordingly; Step 2: Based on the equivalent diffusion λ, the first equivalent relationship is used to inversely calculate the atmospheric water loss coefficient ζ at the outlet boundary during the vertical flow of the super-large rounded flared tube. A ; Step 3: Based on the equivalent diffusion λ, the local diffusion loss coefficient ζ at the outlet boundary of the super-large rounded flare tube during vertical flow is inversely calculated using the second equivalent relationship: B ; Step 4: The atmospheric water loss coefficient ζ A and the local diffusion loss coefficient ζ B By superposition, the total vertical surge boundary loss W of the super-large rounded flare tube is calculated according to the third relationship.

2. The method for estimating the vertical surge boundary loss of the super-large size rounded horn according to claim 1 is characterized in that: The calculation of the equivalent diffusion λ in step 1 includes: Where D1 is the inlet boundary diameter, D2 is the outflow boundary diameter, and H is the distance between the inlet boundary and the outflow boundary.

3. The method for estimating the vertical surge boundary loss of the super-large size rounded horn according to claim 1 is characterized in that: The first equivalent relationship in step 2 is: In the formula, β1 is the first empirical parameter, β2 is the second empirical parameter, β3 is the third empirical parameter, β4 is the fourth empirical parameter, β5 is the fifth empirical parameter, β6 is the sixth empirical parameter, and β7 is the seventh empirical parameter.

4. The method for estimating the vertical surge boundary loss of the super-large size rounded horn according to claim 3 is characterized in that: In the first equivalent relationship formula: the first empirical parameter β1 = 0.0028, the second empirical parameter β2 = -0.3112, the third empirical parameter β3 = 0.2333, the fourth empirical parameter β4 = -0.0542, the fifth empirical parameter β5 = -9.1, the sixth empirical parameter β6 = 1.35, and the seventh empirical parameter β7 = 2.

9.

5. The method for estimating vertical surge boundary loss of an oversized rounded horn according to claim 1 is characterized in that: The second equivalent relationship in step 3 is: λ+(α1+α2·ζ B )=0 Wherein, α1 is the eighth empirical parameter, and α2 is the ninth empirical parameter.

6. The method for estimating the vertical surge boundary loss of the super-large size rounded horn according to claim 5 is characterized in that: In the second equivalent relationship formula: the eighth empirical parameter α1=2.1591, the ninth empirical parameter α2=-3.0847.

7. The method for estimating vertical surge boundary loss of an oversized rounded horn according to claim 1 is characterized in that: The total vertical surge boundary loss W of the oversized rounded flared tube in step 4 is: Where g is the acceleration of gravity, π is the circumference constant, and Q is the water flow rate of the rounded horn pipe.

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