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『Experimental Report on Venturi Flow Meter』Related information(clamp on meter|electromagnetic meter|venturi meterrotameter|orifice meter|ultrasonic flow meter|mass flow meter|coriolis mass flow meter|coriolis flow meter|magnetic flow meter|magmeter flow meter|magflow flow meter|mag meter flow meter|electromagnetic flow meter|vortex flow meter|turbine flow meter|thermal mass flow meter|thermal flow meter|rotameter flow meter)
What are the factors that affect the flow coefficient of the Venturi flowmeter experiment? Which factor is most sensitive ..
The size of the μ value in this experiment (water as a fluid) is related to the actual flow rate, imaginary sign, and the large difference between the differential pressure gauge. Among them, the diameter D1 and D2 have the most significant and sensitive effects. For example, when the maximum flow rate is reached, the μ value is 0.976. If the error of D2 is -0 01cm， So the value of μ will become 1.006, which is obviously unreasonable.
2. Evaluation of calibration uncertainty of Venturi flowmeter
The core of uncertainty evaluation of Venturi flowmeter calibration is to systematically analyze the sources of errors in each link and achieve quantitative synthesis of errors through mathematical modeling. 1. Accurate construction of measurement model. The calculation model of the Venturi flowmeter is based on the Bernoulli equation, with the core formula being Q=C · A ₀·√ (2 Δ P/ρ). The accuracy of the flow coefficient C, throat cross-sectional area A ₀, pressure difference Δ P, and fluid density ρ directly determines the reliability of the final calculation result. When deriving the model, it is necessary to consider the compressibility and viscosity effects of the fluid. 2. Three dimensional perspective equipment error for error tracing: the accuracy error of differential pressure sensors, such as ± 0.1% range, will amplify the deviation of the grinding tool Δ P, and the accuracy error of calipers for throat diameter measurement will cause A ₀ square level amplification. The temperature compensation failure of the laboratory densitometer may cause a deviation of more than 0.3%
4. The matrix operation of error synthesis calculates the sensitivity coefficients for each component: ∂ Q/∂ C=Q/C ≈ 100%, ∂ Q/∂ A ₀=2Q/A ₀ ≈ 200%, ∂ Q/∂ Δ P=0.5Q/Δ P ≈ 0.5%, ∂ Q/∂ ρ=-0.5Q/ρ≈ -0.5%. When constructing the covariance matrix, special attention should be paid to the coupling effect of temperature on Δ P and ρ, which may contribute more than 15% of the composite error under severe temperature conditions.
5. Engineering confirmation of extended uncertainty When the composite standard uncertainty uc=0.38%, selecting the inclusion factor of k=2 can result in U=0.76%. At the boundary points of