3D Inverse Design Loading Strategy for Transonic Axial Compressor Blading

Author(s):  
A. J. Medd ◽  
T. Q. Dang ◽  
L. M. Larosiliere

A pressure-loading tailoring scheme for transonic axial compressor blading is developed with the goal of managing the passage shock in order to reduce loss and enhance stability. This loading distribution along with other prescribed quantities is employed in a 3-D viscous inverse design procedure to refine initial rotor blade geometries of an advanced 2-stage transonic compressor. Key features of this loading strategy are discussed in the context of their impact on flow structure and performance. Results are presented showing the merits of this scheme.

Author(s):  
Garth V. Hobson ◽  
Anthony J. Gannon ◽  
Scott Drayton

A new design procedure was developed that uses commercial-off-the-shelf software (MATLAB, SolidWorks, and ANSYS-CFX) for the geometric rendering and analysis of a transonic axial compressor rotor with splitter blades. Predictive numerical simulations were conducted and experimental data were collected in a Transonic Compressor Rig. This study advanced the understanding of splitter blade geometry, placement, and performance benefits. In particular, it was determined that moving the splitter blade forward in the passage between the main blades, which was a departure from the trends demonstrated in the few available previous transonic axial compressor splitter blade studies, increased the mass flow range with no loss in overall performance. With a large 0.91 mm (0.036 in) tip clearance, to preserve the integrity of the rotor, the experimentally measured peak total-to-total pressure ratio was 1.69 and the peak total-to-total isentropic efficiency was 72 percent at 100 percent design speed. Additionally, a higher than predicted 7.5 percent mass flow rate range was experimentally measured, which would make for easier engine control if this concept were to be included in an actual gas turbine engine.


Author(s):  
Gregory Bloch ◽  
James Loellbach ◽  
Chunill Hah

A numerical investigation of unsteady blade row interaction in a transonic axial compressor was performed. The compressor consists of an upstream wake generator (WG) blade row followed by a rotor blade row. Blade row interaction consists of two main effects: the downstream influence on the rotor flowfield of wakes and unsteady vortices shed from the wake generator, and the upstream influence on the wake generator of the rotor bow shock waves. An unsteady, two-dimensional, Navier-Stokes simulation was performed at the 75% span location of the compressor. Results from the numerical simulation are compared to previously reported numerical results and to experimental measurements from a similar case.


1991 ◽  
Author(s):  
Jacques Paulon ◽  
Zhifang Zhang ◽  
Pingfang Jia ◽  
Jingfei Meng

Interaction phenomena between rotor and stator are unavoidable in advanced compressors and their effects increase with the performances of the turbomachines. Until now, it was not possible to quantify the interaction effects, but with the development of 3-D unsteady computation codes in a complete stage, it is possible to know, in detail, the flow field through the machine and to make evident and to explain the difficulties encountered in measuring the flow parameters. A study has been conducted in this way at ONERA, on an axial transonic compressor stage. The computations have been made with a simulation of the losses; in this manner, the overall computed and measured performances of the compressor are the same. A detailed analysis of the unsteady computation results makes evident, between rotor and stator, large variations of some parameters of the flow as a function of time but also as a function of the axial and tangential relative position of steady probes and stator blades. Unsteady measurements made on another transonic machine confirm the indications given by these computations.


Author(s):  
Adel Ghenaiet ◽  
Nouredine Djeghri

This paper presents a multi-block solver dealing with an inviscid three dimensional compressible flow through a transonic compressor blading. For efficient computations of the 3D time dependant Euler equations, this solver that we have developed has been cast within a stationary ALE ‘Arbitrary Lagrangian Eulerian’. The main contribution of this paper is by consolidating this ALE formulation, to alleviate the shortcomings linked to rotation effects and the mixed relative subsonic–supersonic inlet flow conditions, which are now simply implemented through an absolute subsonic flow velocity. The finite volume based solver is using the central differencing scheme known as JST (Jameson-Schmidt-Turkel). The explicit multistage Runge-Kutta algorithm is used as a pseudo time marching to the steady-state, coupled with two convergence accelerating techniques; the variable local time-stepping and the implicit residual smoothing procedure. The adaptive implicit residual smoothing has extended the stability range of this explicit scheme, and proved to be successful in accelerating the rate of convergence. This code is currently being extended to include viscous effects, where fluxes are discretized based on Green’s theorem. To support this solver, an H type grid generator based on algebraic and elliptic methods has been developed. The segmentation of the complete domain into smaller blocks has provided full topological and geometrical flexibilities. The code was used to compute the flow field of a transonic axial compressor NASA rotor 37, and comparisons between the calculations and some available experimental data under the design speed and part speed, show qualitatively good agreement.


Author(s):  
Haixin Chen ◽  
Xudong Huang ◽  
Ke Shi ◽  
Song Fu ◽  
Matthew A. Bennington ◽  
...  

Numerical investigations were conducted to predict the performance of a transonic axial compressor rotor with circumferential groove casing treatment. The Notre Dame Transonic Axial Compressor (ND-TAC) was simulated by Tsinghua University with an in-house CFD code (NSAWET) for this work. Experimental data from the ND-TAC were used to define the geometry, boundary conditions and data sampling method for the numerical simulation. These efforts, combined with several unique simulation approaches, such as non-matched grid boundary technology to treat the periodic boundaries and interfaces between groove grids and the passage grid, resulted in good agreement between the numerical and experimental results for overall compressor performance and radial profiles of exit total pressure. Efforts were made to study blade level flow mechanisms to determine how the casing treatment impacts the compressor’s stall margin and performance. The flow structures in the passage, the tip gap and the grooves as well as their mutual interactions were plotted and analyzed. The flow and momentum transport across the tip gap in the smooth wall and the casing treatment configurations were quantitatively compared.


Author(s):  
Yuyun Li ◽  
Zhiheng Wang ◽  
Guang Xi

The Inlet distortion, which may lead to the stability reduction or structure failure, is often non-ignorable in an axial compressor. In the paper, the three-dimensional unsteady numerical simulations on the flow in NASA rotor 67 are carried out to investigate the effect of inlet distortion on the performance and flow structure in a transonic axial compressor rotor. A sinusoidal circumferential total pressure distortion with eleven periods per revolution is adopted to study the interaction between the transonic rotor and inlet circumferential distortion. Concerning the computational expense, the flow in two rotor blade passages is calculated. Various intensities of the total pressure distortion are discussed, and the detailed flow structures under different rotating speeds near the peak efficiency condition are analyzed. It is found that the distortion has a positive effect on the flow near the hub. Even though there is no apparent decrease in the rotor efficiency or total pressure ratio, an obvious periodic loading exists over the whole blade. The blade loadings are concentrated in the region near the leading edge of the rotor blade or regions affected by the oscillating shocks near the pressure side. The time averaged location of shock structure changes little with the distortion, and the motion of shocks and the interactions between the shock and the boundary layer make a great contribution to the instability of the blade structure.


Author(s):  
André Inzenhofer ◽  
Cyril Guinet ◽  
Andreas Hupfer ◽  
Bernd Becker ◽  
Patrick Grothe ◽  
...  

Tip blowing and axial slot casing treatments have shown their ability to enhance the stability of a transonic axial compressor with different effects on efficiency. For an effective application of these casing treatments, a good knowledge of the influence of the casing treatment on the rotor flow field is important. There is still a need for more detailed investigations, in order to understand the interaction between the treatment and the near casing 3D flow field. For transonic compressor rotors this interaction is more complex, as super- and subsonic flow regions alternate while interacting with the casing treatment. In the present study, an axial slot and a tip blowing casing treatment, which have been developed and optimized for the same tip critical transonic axial compressor rotor (reference rotor) by Streit et al. [1] and Guinet et al. [2], are subject of the investigation. Both casing treatment types showed their capabilities to enhance the compressor stability without losing by means of CFD simulations. Since the higher compressor stability allows a higher blade loading, Streit et al. reduced the blade number of the rotor. Thus, the efficiency was increased due to the reduction of friction losses. However, applying the tip blowing casing treatment to the reduced rotor shows a negative effect on the efficiency. Both casing treatment types recirculate flow from a downstream to an upstream location of the rotor and reinject it to enhance the near casing flow field. Although the working principle of the two casing treatment types are similar, the transfer of the casing treatments from the reference to the reduced rotor show different trends in efficiency. Therefore, the effect of recirculation cannot explain the difference in efficiency. Hence, applying axial slots must include additional flow features, compared to recirculation channels. Compensating effects as in circumferential groove casing treatments and other flow interactions between the near casing flow field and the slot flow are considered. These additional mechanisms of the axial slot casing treatment will be identified and isolated by comparing the two different casing treatment types. The numerical simulations are carried out on a 1.5 stage transonic axial compressor using URANS simulations.


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