Measurements of air–water flow properties are reasonably simple in steady flows, but not so in unsteady flows. Some studies investigated periodic flows in which instantaneous data were averaged over several cycles. During the present work, new unsteady air–water flow measurements were performed in sudden open channel flow surges. Unsteady air–water flow measurements were performed in the wave f...

In this work, an unsteady state analysis of the compression cycle of a small hermetic reciprocating compressor for domestic refrigeration was carried out. The mass and energy balances were applied to the refrigerant inside the cylinder in order to determine the mass and temperature behaviour through the compression process. A specific onedimensional model of the valves was developed to calculat...

The linear flow analysis of turbomachinery aeroelasticity views the unsteady flow as the sum of a background nonlinear flow field and a linear harmonic perturbation. The background state is usually determined by solving the nonlinear steady flow equations. The flow solution representing the amplitude and phase of the unsteady perturbation is instead given by the solution of a large complex line...

E↵ect of acoustic waves on the control performance of distributed micron-sized roughness elements in a swept-wing boundary layer is investigated through direct numerical simulations. The flow configuration conforms to experiments by Kachanov et al. (2015) who observed either no significant influence of acoustic waves on the transition location or small stabilisation e↵ect. In this work, a base ...

The quest for the ever-greater operational flexibility of large-scale steam turbines continues to drive enhanced control valve design. Such components, subjected to large static loads, also may experience strong vibrations due to unsteady turbulent fluctuations downstream of the throttling section. Challenging design efforts are required to ensure that these fluctuations are confined far from s...

Title of dissertation: DEVELOPMENT OF A TIME-ACCURATE VISCOUS LAGRANGIAN VORTEX WAKE MODEL FOR WIND TURBINE APPLICATIONS Sandeep Gupta, Doctor of Philosophy, 2006 Dissertation directed by: Minta Martin Professor J. Gordon Leishman, Department of Aerospace Engineering A second-order accurate model has been developed and validated for modeling the unsteady aerodynamics of a wind turbine. The free...

Accurate steady and unsteady numerical solutions of the full 2-D governing equations – that model the forced film condensation flow of saturated vapor over a semi-infinite horizontal plate (the problem of Cess [1] and Koh [2]) are obtained over a range of flow parameters. The results presented here are used to better understand the limitations of the well-known similarity solutions given by Koh...

The unsteady flow of a visco-elastic Maxwell fluid through a rectilinear pipe having its cross-section as a parallelogram under the influence of a axial pressure gradient (I) varying linearly with time , and (II) decreasing exponentially with time has been discussed in the present paper. Variables separable and Laplace transform methods have been used to solve the problem.  

Numerical simulations of the natural and actuated unsteady flow over a three-dimensional low-aspect ratio wing are performed using Lattice Boltzmann method. The LBM simulations match the flow conditions and the detailed wing geometry from previous experiments, including the actuators that are installed internally along the leading edge of the wing. The present study focuses on the transient lif...

A CFD solver is developed to solve a 3D, unsteady, compressible Navier-Stokes equations with the Baldwin-Lomax turbulence model to study the unsteady separation flow in a high incidence cascade. The second order accuracy is obtained with the dual time stepping technique. The code is first validated for its unsteady simulation capability by calculating a 2D transonic inlet diffuser flow. Then a ...