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『Hydraulic flow calculation formula』Related information(flow rotameter|digital flow meter|balo meter|hydraulic flow meter|volumetric meter|positive displacement meter|pitot tube flow meter|displacement meter|cfm meter|variable area flow meter|inline flow meter|differential pressure flow meter|calibrated flow meter|velocity meter|paddle wheel flow meter|oval gear flow meter|anemometer hvac|multiphase flow meter|doppler flow meter|thorpe tube flowmeter|heat flow meter)
1. Calculation formula for water flow rate and velocity
The equation for flow rate is Q=Sv=constant (where S is the cross-sectional area and v is the water flow velocity) (in fluid mechanics, Q=AV is used), with the unit being cubic meters per second. When an incompressible fluid flows steadily, the flow rate through each section of the same flow tube remains constant. The measurement of fluid flow rate within a certain channel is collectively referred to as flow metering. The fluids used for flow measurement are diverse, such as gases, liquids, and mixed fluids; The temperature, pressure, and flow rate of fluids vary greatly, and the required measurement accuracy also varies. Therefore, the task of flow measurement is to study various corresponding measurement methods based on the measurement purpose, the type and flow state of the measured fluid, the measurement location, and other measurement conditions, and ensure the correct transmission of flow values. The velocity field is composed of the collection of velocities at various spatial points along the streamline. Streamline is the geometric representation of the velocity field. It is a curve composed of different fluid particles at the same moment, and the velocity vectors of all particles on the line are tangent to the curve. The streamline diagram formed by the streamlines passing through the points between the flowing voids at the same moment provides a clear image of the entire flow at that moment. If the point flow velocity does not change with time, it is a constant flow; Otherwise, it is a non steady flow. The streamline and streamline diagram of unsteady flow vary over time. The above content refers to: Baidu Baike - Flow rate
2. Calculation
Calculation of water level flow relationship from section data can be achieved through specific formulas, Mannings formula, or fitting with measured data. The specific method needs to be selected based on the data type and calculation requirements. 1. Using a specific formula to calculate the mathematical relationship between the known water level (z), flow rate (Q), and discharge area (Shi Li Jing A), it can be directly calculated through the formula. For example, a certain river channel adopts the following relationship: flow formula: $Q=5 (z-50) ^ {1.4} $area formula: $A=100 (z-50) ^ {1.0} $calculation process: reverse calculation of water level: when the design flow Q is known, the water level z is obtained by solving the equation $z=50+(Q/5) ^ {1/1.4} $. Calculation of water area: z is substituted into the area formula to obtain the corresponding water area A. Calculation of flow velocity: using the formula $v=Q/A $, the average flow velocity v is obtained. This method is suitable for theoretical models or simplified scenarios, but it is necessary to ensure that the formula parameters match the actual characteristics of the river channel, otherwise errors may occur.
2. Based on Mannings formula The Manning formula is a widely used empirical formula in hydraulics, suitable for calculating the water level flow relationship of natural or artificial channels. The formula is: $Q=frac {A cdot R {1/2}} {n} $, where R is the hydraulic radius ($R=A/L $, L is the wetted perimeter), n is the roughness (reflecting the roughness of the riverbed), and J is the water surface gradient. Calculation process: Determine parameters: Obtain roughness n, gradient J, and cros