Nt1310 Unit 3 Lab Report
erical methPage 48
Licentiate Thesis / Nenad Glodic
6 NUMERICAL INVESTIGATIONS 6.1 Numerical Method
Numerical simulations are carried out employing a commercial CFD code (ANSYS CFX v11). The solver is using a full-scale time-marching 3D viscous model. Underlying equations, three dimensional Navier-Stokes equations in their conservation form, are being solved by using a Finite Volume method, where equations are integrated over the finite control volumes. Thereby, the solution domain is subdivided into a finite number of control volumes employing a suitable grid, which defines the control boundaries around a computational node in each control volume center. 6.1.1 Governing equations In fluid dynamics, the fluid flow is governed by the conservation laws for mass, momentum and energy. The basic conservation laws are formulated by using Leibniz-Reynolds transport theorem, which is an integral relation stating that the changes of some intensive property defined over a control volume must be equal to what is lost (or gained) through the boundaries of the volume plus what is created/consumed by sources and sinks inside the control volume. The …show more content…
This solution is then used as initial value for the transient simulation. In the unsteady simulations, the motion of the center blade was prescribed by a set of equations for the requested mode. The correctness of the imposed motion is confirmed by an analytical model. A timemarching solution was acquired spanning typically 3 oscillation periods. The flow could be regarded as time periodic already after the second oscillation cycle (criterion used: >0.5% phase-locked difference). A time trace of unsteady pressure coefficient at a chosen point on the blade surface is presented in Figure 6.3. One oscillation period was resolved by 20 time steps and with three iteration loops per time
Licentiate Thesis / Nenad Glodic
6 NUMERICAL INVESTIGATIONS 6.1 Numerical Method
Numerical simulations are carried out employing a commercial CFD code (ANSYS CFX v11). The solver is using a full-scale time-marching 3D viscous model. Underlying equations, three dimensional Navier-Stokes equations in their conservation form, are being solved by using a Finite Volume method, where equations are integrated over the finite control volumes. Thereby, the solution domain is subdivided into a finite number of control volumes employing a suitable grid, which defines the control boundaries around a computational node in each control volume center. 6.1.1 Governing equations In fluid dynamics, the fluid flow is governed by the conservation laws for mass, momentum and energy. The basic conservation laws are formulated by using Leibniz-Reynolds transport theorem, which is an integral relation stating that the changes of some intensive property defined over a control volume must be equal to what is lost (or gained) through the boundaries of the volume plus what is created/consumed by sources and sinks inside the control volume. The …show more content…
This solution is then used as initial value for the transient simulation. In the unsteady simulations, the motion of the center blade was prescribed by a set of equations for the requested mode. The correctness of the imposed motion is confirmed by an analytical model. A timemarching solution was acquired spanning typically 3 oscillation periods. The flow could be regarded as time periodic already after the second oscillation cycle (criterion used: >0.5% phase-locked difference). A time trace of unsteady pressure coefficient at a chosen point on the blade surface is presented in Figure 6.3. One oscillation period was resolved by 20 time steps and with three iteration loops per time