Previous work on stabilization of compressor surge is extended to include control of the angular velocity of the compressor. First a low-order centrifugal compressor model is presented where the states are mass flow, pressure rise, and rotational speed of the spool. Energy transfer considerations are used to develop a compressor characteristic. In order to stabilize equilibria to the left of th...

In this paper we develop a globally stabilizing stability-based switching controller for a three-state lumped parameter centrifugal compressor surge model. The proposed model involves pressure and mass flow compression system dynamics as well as spool dynamics to account for the influence of speed transients on the compression surge dynamics. The proposed nonlinear switching controller architec...

This investigation presents an active stability control system on a twin-spool turbofan engine to recover from unstable operating conditions or to avoid them. Therefor air injection in the tip region ahead of the first low pressure compressor (LPC) rotor is used to damp any instabilities and their precursors. A high frequency instrumentation is applied to detect the flow disturbances and to fee...

This paper focuses on the conceptual design of a two spool compressor for the NASA Large Civil Tilt Rotor engine, which has a design-point pressure ratio goal of 30:1 and an inlet weight flow of 30.0 lbm/sec. The compressor notional design requirements of pressure ratio and low-pressure compressor (LPC) and high pressure ratio compressor (HPC) work split were based on a previous engine system s...

This paper describes development of water hydraulic proportional valves. The valves are spool-type and the spool is driven by a stepping motor and positive cam mechanism. The cam is always placed between two cam followers and the return spring is omitted. The rotational angle of the cam and the displacement of the spool is linear. The experimental results of static characteristics are also show...

The objective of the present paper is a numerical analysis of the flow forces acting on spool surfaces of a pressure regulated valve. The transient, compressible and turbulent flow structures inside the valve are simulated using ANSYS FLUENT coupled with a special UDF. Here, valve inlet pressure is varied in a stepwise manner. For every value of inlet pressure, transient analysis leads to a qua...

The input to an electro-hydraulic (EH) servovalve is typically a current or a differential current that powers an electromagnetic torque motor. The differential current Δi is typically supplied by an amplifier to avoid excess loading of the interface to the computer or controller. In the simplest (but not typical) form, the torque motor moves a spool valve as shown below. The spool valve allows...