Performance Of Compressor Cascade Research Articles

A Numerical Investigation of Boundary Layer Suction in Compound Lean Compressor Cascades

This paper is focused on the numerical investigation of boundary layer suction (BLS) via a slot on the suction surfaces of two compound lean compressor cascades with large camber angles as well as a conventional straight compressor cascade for comparison. The objective of the investigation is to study the influence of boundary layer suction on the performance of compound lean compressor cascades, thus to discuss the possibility of the application of boundary layer suction to improve their performance. An extensive numerical study has been carried out under different spanwise lengths, different axial positions of the slots, and different suction flow rates. The results show that the total loss of all three cascades is reduced significantly by boundary layer suction, and the largest reduction occurs at the highest suction flow rate. The axial locations of the slot have little effect on the total loss of the three cascades, which means the slots are opened within the optimal axial range in this case. The slot opened along the full span is the best one to obtain the largest reduction in total loss for all three cascades due to the alleviation of flow separation in the corner between the endwall and the suction surface. Moreover, the flow turning is increased, and pressure rise at the rear of the passage is recovered along the whole blade height via boundary layer suction along the full span, enhancing the working range of the highly loaded compressor cascades.

Closure to “Discussion of ‘Comparison of Sweep and Dihedral Effects on Compressor Cascade Performance’” (1998, ASME J. Turbomach., 120, pp. 463–464)

Closure to “Discussion of ‘Comparison of Sweep and Dihedral Effects on Compressor Cascade Performance’” (1998, ASME J. Turbomach., 120, pp. 463–464)

Comparison of Sweep and Dihedral Effects on Compressor Cascade Performance

The influence of two stacking lines, namely sweep and dihedral, has been investigated in a linear compressor cascade. Both types of blade considered are symmetric about midspan and consist of a straight central section with either swept or dihedral sections toward the endwalls. Two types of experiment have been carried out. First, a parametric study was performed by changing both the magnitude and the extent of the sweep or dihedral. In the case of swept blades, those with forward sweep (SWF), for which the stacking line is swept in the upstream direction toward the endwall, were found to have better performance than backward-swept blades. Subsequently, four sets of SWFs were compared. In the case of dihedral blades, it is well known that the dihedral is advantageous when the angle between the suction surface and the endwall is obtuse, i.e., positive dihedral. Thus, four sets of positive dihedral blades (DHP) were compared. In both SWF and DHP blades, those configurations that have better efficiency than straight blades were determined. Second, detailed three-dimensional measurements inside the blade passage were performed in the cases that showed the best performance in the parametric study. Both SWF and DHP showed significant effects on the flowfield. In the SWF case, a vortex, which has the opposite sense to the passage vortex, was observed in the forward portion inside the blade passage. This vortex supplies high-energy fluid to the endwall region and reduces the corner stall. The secondary flow is greatly reduced. In the DHP, the blade loading was reduced at the endwall and increased at the midspan. Reduction of the corner stall and the secondary flow was also observed.

Experimental investigations on tandem compressor cascade performance at low speeds

Minimizing the number of axial flow compressor stages for a specific work output, and thereby lowering the engine size and weight, has always been the designer's goal. Recently, with the emergence of low aspect ratio blades, there has been a renewed interest in tandem blading for maximizing the blade loading further besides improving its off-design performance characteristics. This paper presents aerodynamic performance evaluations of three assorted cascades of single (CDA 43), tandem (CDA 21-21), and a newly developed tandem (CDA 32-21) blading. Fundamental investigation has been attempted in a low speed cascade wind tunnel to find the high deflection capability of tandem cascades. Although limited performance of tandem CDA 21-21 has been affected by certain grey areas covering both geometric and aerodynamic shortfall, tandem CDA 32-21 derived from CDA 43 and CDA 21-21 has shown high flow deflection characteristics and hence high loading over a wide range of angle of attack.

Experimental research on secondary flows in cascade of blades. Effects of blade aspect ratio on the performance of compressor cascade with regard to the Reynolds number effect.

The performance of the compressor-type cascade blades of small aspect ratio (AR, AR=2.08, 1.39, 1.04 and 0.83) at the center of the blade span has been experimentally assessed. The relation between the performance and Reynolds number (Re) is obtained. This relation is used to eliminate the Re effect on performance. Consequently, pure effects of blade AR on performance, i. e., total pressure loss, turning angle and axial velocity ratio, are obtained.

Prediction of Compressor Cascade Performance Using a Navier–Stokes Technique

An explicit, time marching, multiple-grid Navier–Stokes technique is demonstrated for the prediction of quasi-three-dimensional turbomachinery compressor cascade performance over the entire incidence range. A numerical investigation has been performed in which the present Navier–Stokes procedure was used to analyze a series of compressor cascade viscous flows for which corresponding experimental data are available. Results from these calculations show that the current viscous flow procedure is capable of predicting cascade profile loss and airfoil pressure distributions with high accuracy. The results from this numerical investigation in the form of comparisons between the predicted profile loss, exit gas angle, and pressure distributions with experimental data are presented in this paper. Results from a grid refinement study are also shown to demonstrate that the Navier–Stokes solutions are grid independent.

The Combined Effect of Axial Velocity Density Ratio and Aspect Ratio on Compressor Cascade Performance

The paper describes theoretical and experimental investigations on the combined effect of axial velocity density ratio (AVDR) and aspect ratio (AR) on compressor cascade performance in incompressible and compressible flow. The results presented demonstrate that it is the aspect ratio that defines the axial velocity distribution through the cascade at a given wall shape and contraction ratio. It is further shown that it is, in turn, the axial velocity distribution that decisively determines the local values of pressure distributions as well as the cascade overall parameters like turning angles and loss coefficients.

The Effect of Reynolds Number and Turbulence Intensity on the Performance of a Compressor Cascade with Prescribed Velocity Distribution

Experimental results are presented on the effect of Reynolds number ( Re) and turbulence intensity ( Tu) on the aerodynamic performance of a PVD compressor cascade at design incidence. The pressure distribution, outlet flow angle and losses were measured within the ranges Re = 0.6 times 105 to 2 times 105 and Tu = 0.35 to 4.4 per cent. In some experiments, the effect of axial velocity ratio ( AVR) was investigated. A substantial effect of the Reynolds number and turbulence intensity on the growth and bursting of the separation bubble was observed, with consequent effects on the aerodynamic performance of the cascade. The bursting of the bubble also gave rise to a hysteresis effect with Reynolds number.

Cascade Tests of High Stagger Compressor Blades

The aim of this report is to obtain the two-dimensional performance of compressor cascade with high stagger. The results are as follows : 1) The test method to obtain two-dimensional performance of compressor cascades has been determined. 2) The tests were carried out successfully and the performances of compressor cascades were obtained for 31 combinations of the pitch chord ratio S/C=0.7, 1.0, 1.2, and the stagger angle ξ=45°, 50°, 60°, 65°to each of the camber Clo =0.0, 0.4, 0.8, 1.2. 3) The design points were selected and the design loading limits were derived from the cascade data.