Numerical analysis of sweep effects in shrouded propfan rotors

Helming, Klaus

doi:10.2514/3.24002

Cited by 11 publications

(12 citation statements)

References 5 publications

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“…Sweep introduces three-dimensionality to the originally 2D throughflow (via cylindrical stream surfaces), elongating the flow path, as explained in reference [25] and illustrated in reference [26]. As reference [17] reports, the streamlines of swept rotors indicate a longer trajectory of the particles over the suction surface, which was found to increase the BL thickness. Even minor changes in flow path length were found to cause remarkable change in growth of the BL.…”

Section: Justificationmentioning

confidence: 92%

Correlation of flow path length to total pressure loss in diffuser flows

Vad

2011

Proceedings of the Institution of Mechanical Engineers, Part A:

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This article studies the effect of changing the flow path length on development of total pressure loss in diffuser flows. The studies incorporate quasi-one-dimensional (conical diffuser), two-dimensional (linear blade cascade), and three-dimensional (annular blade cascade) flows. This article concludes that the consequence of decreasing the flow path length is to decrease total pressure loss, provided that the adverse streamwise pressure gradient remains subcritical. The loss calculation technique and measurement data published by Lieblein were post-processed in this article. On this basis, this article elaborates a method for estimating the total pressure loss as well as its modification due to change of flow path length in blade cascade flows. This method can contribute to preliminary axial flow rotor blade design. It was pointed out that, in comparison to free vortex design, controlled vortex design that is applied to straight axial flow rotor blades tends to represent an additional source of total pressure loss farther from the endwalls. This is due to elongation of the length of flow paths on the blade suction side, due to intensified radial outward flow. This adverse effect can be counterbalanced by incorporation of forward sweep in controlled vortex design, via shortening the flow paths on the suction side, without the beneficial features of the controlled vortex design being lost. This article presents a literature-based comparative case study to illustrate such loss-reducing effect of incorporating forward sweep in controlled vortex design, away from the endwalls.

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Section: Justificationmentioning

confidence: 92%

Correlation of flow path length to total pressure loss in diffuser flows

Vad

2011

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…The effect of skin friction is increased along the 3D paths of increased length [20]. Therefore, as pointed out in reference [4], introduction of sweep may intensify the thickening of the boundary layer, leading potentially to increased losses.…”

Section: Moderate Flow Rate and High Flow Ratementioning

confidence: 99%

“…positive sweep, have been pointed out, e.g. in compressors, in general [1], in low-speed linear cascades [2,3], in transonic fan rotors [4,5], and in stators of low-speed [6] and transonic compressors [7]. For low-speed fans and compressors, the application of forward sweep along the entire span is often suggested for loss reduction and performance improvement [8 -12].…”

Section: Introductionmentioning

confidence: 99%

Effects of blade sweep on the performance characteristics of axial flow turbomachinery rotors

Vad

Kwedikha

Jaberg

2006

Proceedings of the Institution of Mechanical Engineers, Part A:

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Experimental studies were carried out in order to survey the performance and efficiency aspects of spanwise constant forward and backward sweep in axial flow rotors of low aspect ratio (AR) blading for incompressible flow, for part-load, near-design, and overload operational ranges. The experiments involved overall performance tests, laser Doppler velocimetry, and stationary total pressure probe measurements. The overall performance data and pitchwise averaged and resolved flow characteristics were evaluated in detail. For moderate and high flow rates, it was pointed out that positive or negative sweep tends to reduce or increase the blade load in the vicinity of the endwalls, respectively. It has been concluded that the loss-modifying effect of sweep can be judged by considering the three-dimensional viscous phenomena, and the influence of sweep on local blade efficiency depends on the balance of changes in blade load and losses. For low flow rates, forward sweep was found beneficial over the entire span from the aspect of improved stall margin and efficiency. The influence of AR on the performance reducing effect of sweep was studied on the basis of literature data.

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“…On the basis of five case studies reported in the literature [10,11,[14][15][16], they sought the following correlations between the sweep angle and the ratio of pressure coefficients of comparative swept and unswept rotors by modifying the equations (1) and (2), respectively, as follows: Figure 1 presents the corresponding 1/AR as well as A and B data pairs calculated from the literature data. Next to the data points, the literature source and the actual λ value are specified.…”

Section: Introductionmentioning

confidence: 99%

“…Since the effect of aspect ratio (AR) also contributes to the deviation of the actual behaviour from the one predicted by theory of infinitely long airfoils, Vad et al [13] extended the study on the above estimations to include the effects of the blade AR. On the basis of five case studies reported in the literature [10,11,[14][15][16], they sought the following correlations between the sweep angle and the ratio of pressure coefficients of comparative swept and unswept rotors by modifying the equations ( 1) and (2), respectively, as follows:…”

Section: Introductionmentioning

confidence: 99%

On loading corrections and loss distributions in low-speed forward swept axial compressor rotors

Ramakrishna

Govardhan

2011

Proceedings of the Institution of Mechanical Engineers, Part A:

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Loading of a swept aerofoil blade is typically reduced as its lifting line is inclined (at the sweep angle) with the radial direction. Various estimations are available in the literature about the correction to be made on the loading of a wing when the same is swept. However, it is difficult to obtain an accurate and a more general estimation of correction for a range of sweep angles and for a range of mass flowrates. This article presents two aspects of the flow field in forward swept compressor blade passages: (a) Loading of swept rotors from the present computational study (on a baseline unswept rotor and forward swept rotors of 20 • , 30 • , and 40 • sweep angles; for different tip clearance and stagger configurations) is compared with a number of load correction estimations reported in the literature. Loading of the swept rotors obtained through numerical simulations is compared with the existing estimations obtained from the loading of unswept rotor. A correction factor blend is evaluated, which is found to provide good estimations of loading characteristics for various sweep configurations. (b) Spanwise and streamwise resolved loss coefficient distributions are studied, which showed that the high endwall losses observed in the unswept rotor were significantly reduced with blade sweeping. However, tip clearance is found to result in increased overall loss in the swept rotors.

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Numerical analysis of sweep effects in shrouded propfan rotors

Cited by 11 publications

References 5 publications

Correlation of flow path length to total pressure loss in diffuser flows

Correlation of flow path length to total pressure loss in diffuser flows

Effects of blade sweep on the performance characteristics of axial flow turbomachinery rotors

On loading corrections and loss distributions in low-speed forward swept axial compressor rotors

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