A Method for the Prediction of Supersonic Compressor Blade Performance

Abstract

A simple model is used to calculate the flow in compressor blades with supersonic relative inlet flow. The one-dimensional model utilises the conservation of stagnation enthalpy, mass flow and momentum in the inlet region. The momentum equation is applied in the direction parallel to the blade surface at inlet and one of the fundamental simplifications adopted is that the projected area of the blades gives such a small force in this direction that a very simple approximation for it suffices. The model is able to predict the loss creation in the inlet region. The level of predicted loss agree well with measured values when the Mach numbers are sufficiently high for the inlet loss to dominate. Furthermore the correct trends of loss with incidence and blade speed are predicted. The pressure rise and flow can also be predicted when the correct deviation and meridional streamtube convergence are given. The method predicts trends usually seen in measurments: the narrowing of the useful operating range between choke and flow instability (surge) as blade speed is increased and a steepening of the surge line at the higher speeds.

Transonic radial compressor inlet design

“…The design of transonic axial compressor rotors has been the subject of many excellent technical papers over recent years [1,6] and the key objective of this paper is to document the transfer of this know-how and technology to transonic radial compressor inlets.…”

“…In fact, for the case of blades of zero thickness operating at zero incidence, the equations reduce to the standard shock relations. The key equations from this analysis are given in the Appendix, and for further details the readers are referred to the work by Freeman and Cumpsty [1] (see also reference [7]). In the inlet to a radial compressor impeller the assumptions above apply fairly well to the tip of the region commonly known as the inducer, which is the axial section of the impeller blades prior to the bend to the radial direction.…”

“…A theoretical model [1] quanti es the losses in the tip sections caused by the choke margin (incidence) and the blockage of the blades. It identi es clear design rules for the tip sections: to achieve the highest ef ciency, these require minimum blockage (low blade thickness and splitter vanes) and low choke margin (close to the uniqueincidence condition).…”

Application of integrated fuzzy logic and neural networks to the performance prediction of axial compressors

“…32 The accuracy of the present method is evaluated by considering the mean percent error (MPE) between the predicted and experimental data defined as…”

A Transonic Mixed Flow Compressor for an Extreme Duty

“…The blade tip section was designed to operate at the unique incidence condition at the design operating point to minimize the aerodynamic shock losses. The unique incidence condition, where the passage shock is attached to the impeller leading edge, corresponds to minimum shock losses in the entry region [12] and its application to design of axial and centrifugal compressors has been discussed in several references [13,14]. This flow condition can be obtained if the downstream throat, formed by the main and splitter blades and the aerodynamic blockage, is not choked prior to the main passage throat at the impeller inlet.…”