Lab1 Hydraulic plant

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Politecnico di Milano – Department of Aerospace Science and Technology Modeling and Simulation of Aerospace Systems – AY 2015/2016 (F. Topputo) Exercise 1 Part A Referring to Figure 1, there is a pump with variable flow rate: 1. Compute and show the volumetric efficiency, η(x), as a function of the stroke x of the control piston (Considering that the system is at the operating pressure) 2. Model the function Qi(t), the flow rate of the single piston as a function of time, the total flow rate Q(t), and calculate the error (l’irregolarità), I, as a function of the number of pistons Np; 3. Compute the pressurization time for a line with a volume of 5 dm3 considering the initial pressure to be pi = 0.1 MPa in the case of maximum flow rate (Discard the elasticity of pipes). Part B Suppose that the pump is used in the system represented in Figure 2. 1. Considering the mechanism for the pressure regulation, find a values for a) Pre-loading of the spring, b) Stiffness of the spring, in order to assure that the plant works as required; 2. Choose a value for the tank pressure pT, and verify that the system is free from cavitation in the aspirator (inlet). 3. Develop a MATLAB code that allows to obtain pressure and flow rate in each part of the plant as a function of time starting from the given initial conditions. 4. Study the sensitivity of the plant by varying the pump parameters (Consider only the significant pump parameters – use discretion). Note: 1) The fluid is incompressible; 2) Consider the pipe loss only when specified; 3) Compute the pipe loss across the valve considering that the fluid velocity in the pipe is equal to the velocity across the valve.; 4) For the computation of Q2 consider p2 ≃ pA. Figure 2: Hydraulic system (Part B). Figure 1: Variable flow rate pump…