The Current State of the Engineering Method for the Optimal Gas-Dynamic Design and Calculation of Centrifugal Compressor

Abstract

In the practice of centrifugal compressor designing, different engineering techniques are widely used because flow motion differential equations cannot be integrated, and Computational fluid dynamics cannot resolve the problem as a whole. Engineering personal computers’ programs are based on experimental data and the gas dynamics theory. The universal modeling method’s (UMM) mathematical model is a set of equations that determine the pressure loss in the elements of the centrifugal compressor flow path. By the earlier versions of the UMM, dozens of process compressors were designed. Several sets of empirical coefficients for stages of different specific speeds were applied. The paper presents the current state of the universal modeling method that was recently improved. The models of the centrifugal compressor characteristic calculation are described. A new model of the loading factor characteristic, an improved version of the compressor efficiency, and being based on a CFD-calculation vaneless diffuser model are samples of the improvements. Careful identification and verification demonstrate effective characteristic simulation with a single set of empirical coefficients. Centrifugal compressor new design examples of a turbo expander unit and a turbocharger are presented. The calculated characteristics are compared with the test results. For both objects, the experiments confirmed the calculated gas-dynamic characteristics with sufficient accuracy for engineering methods.

Numerical Study on Sensitivity of Turbofan Engine Performance to Blade Count of Centrifugal Compressor Impeller

“…Equation ( 3) is a classical definition of the CPR as a function of four non-dimensional design parameters: isentropic coefficient κ, tip Mach number M u , total-to-total isentropic efficiency η C , and the work input factor I [18,44]:…”

“…Besides, the level of τ w ave /τ w ave re f averaged over the endwall and blades' surfaces grew gradually from 0.92 at z 1 = 7 to 1.09 at z 1 = 13 (Figure 7b). According to [44], these trends should primarily contribute to the growth of the profile efficiency loss ∆η pro f expressed as: The effect of z 1 on the work input coefficient I was assessed based on Figures 8 and 9. Figure 8a shows that the work input reached the maximum at the baseline z 1 = 11 and declined whenever the solidity decreased (z 1 = 9, 7) or increased (z 1 = 13).…”

Mathematical Modelling of the Centrifugal Compressor

“…Today, compressor stations determine the integral impact of the whole existing faults set on the main compressor parameters [10]. The coefficient of the compressor technical state is determined for the estimation of compressor technical state [11]: This thermos-gas-dynamic model is suitable for compressor operation conditions, but accepted for its construction prerequisites (ignoring the actual compressor conditions and its real technical state, gas composition, etc) leads to significant errors in the determining of the centrifugal compressor power and fuel gas discharges.…”