Aerodynamic improved design and optimization for the rear stage of a High-load axial compressor

Abstract

This paper proposes and discusses the aerodynamic retrofit design schemes for a multistage high pressure axial compressor. A high hub/tip ratio mixed-flow compressor is designed and analyzed to replace the rear stage of the axial compressor. In order to minimize the axial dimension and maximize the load capacity, three unconventional types of combined compressors equipped with the high hub/tip ratio mixed-flow compressor are explored. Further, the effects of blade number, splitter blades and dimensionless geometric parameters on the mixed-flow compressor performance are investigated by an improved loss model. A full-surface parameterization control method is introduced and adopted for blade optimizations of the mixed-flow impeller and the tandem stator. The results indicate that after aerodynamic improved design and optimization, the total pressure ratio is relatively improved by 3.71% and the adiabatic efficiency is improved by 0.95 percent point for the mixed-flow compressor at the near design point. Based on this, the retrofit schemes for the axial compressor are beneficial to improve the load capacity and reduce the axial dimension with a slight impact on efficiency and surge margin. These show the potential application prospects of high hub/tip ratio mixed-flow compressors.

Appendices

Appendix

Appendix: Springer-Author Discount

List of symbols

b :

Append Hub-to-shroud passage width

D :

Diameter

f :

Optimized objective function

h :

Blade height

$L$ :

Blade length

Lc :

Blade chord length

$\dot{m}{ }$ :

Mass flow

$P^{*}$ :

Total pressure

Q :

Volume flow

$R_{n}$ :

Design rotate speed

$R_{n}$ :

Design rotate speed

$$\overline{R}{ }\left( {{\text{r}}_{1} + {\text{r}}_{2} } \right)/\left( {{\text{r}}_{2} - {\text{r}}_{1} } \right)$$

r :

Radius

s :

Pitch

$T^{*}$ :

Total temperature

U :

Blade tangential velocity

U :

Blade tangential velocity

Z :

Main blade number

$\beta$ :

Blade angle with respect to tangent

$\gamma$ :

Meridional streamline slope angle

$\Delta H$ :

Total enthalpy increase

$\delta$ :

Tip clearance

$\zeta$ :

Dimensionless splitter blade length

$\eta$ :

Adiabatic efficiency, vertical coordinate

$\eta$ :

Adiabatic efficiency, vertical coordinate

$\xi$ :

Horizontal coordinate

${\uppi }_{{\text{r}}}^{*}$ :

Total pressure ratio

$\tau$ :

Solidity

$\Psi$ :

Loading coefficient

$\phi$ :

Flow coefficient

$\omega$ :

Weight coefficient

Subscripts

B :

Principal blade parameter

h :

Hub

m :

Meridional, mean

nd :

Near design point

ns :

Near stall point

ori :

Original parameters (before optimization)

out :

Outlet

s :

Splitter blade (inlet)

t :

Tip

z :

Axial

1 :

Inlet

2 :

Outlet