0
Research Papers

Wake Analysis of an Aerodynamically Optimized Boxprop High-Speed Propeller

[+] Author and Article Information
Alexandre Capitao Patrao

Department of Mechanics and Maritime Sciences,
Chalmers University of Technology,
Gothenburg SE-41296, Sweden
e-mail: alexandre.capitao.patrao@gmail.com

Tomas Grönstedt

Department of Mechanics and Maritime Sciences,
Chalmers University of Technology,
Gothenburg SE-41296, Sweden
e-mail: tomas.gronstedt@chalmers.se

Anders Lundbladh

GKN Aerospace Sweden & Chalmers University of Technology,
Trollhättan SE-46181, Sweden
e-mail: anders.lundbladh@gknaerospace.com

Gonzalo Montero Villar

Department of Mechanics and Maritime Sciences,
Chalmers University of Technology,
Gothenburg SE-41296, Sweden
e-mail: villar@chalmers.se

1Corresponding author.

Manuscript received August 16, 2018; final manuscript received June 3, 2019; published online July 10, 2019. Assoc. Editor: John Clark.

J. Turbomach 141(9), 091011 (Jul 10, 2019) (13 pages) Paper No: TURBO-18-1208; doi: 10.1115/1.4043974 History: Received August 16, 2018; Accepted June 04, 2019

The Boxprop is a novel, double-bladed, tip-joined propeller for high-speed flight. The concept draws inspiration from the box wing concept and could potentially decrease tip vortex strength compared with conventional propeller blades. Early Boxprop designs experienced significant amounts of blade interference. By performing a wake analysis and quantifying the various losses of the flow, it could be seen that these Boxprop designs produced 45% more swirl than a conventional reference blade. The reason for this was the proximity of the Boxprop blade halves to each other, which prevented the Boxprop from achieving the required aerodynamic loading on the outer parts of the blade. This paper presents an aerodynamic optimization of a 6-bladed Boxprop aiming at maximizing efficiency and thrust at cruise. A geometric parametrization has been adopted which decreases interference by allowing the blade halves to be swept in opposite directions. Compared with an earlier equal-thrust Boxprop design, the optimized design features a 7% percentage point increase in propeller efficiency and a lower amount of swirl and entropy generation. A vortex-like structure has also appeared downstream of the optimized Boxprop, but with two key differences relative to conventional propellers. (1) Its formation differs from a traditional tip vortex and (2) it is 46% weaker than the tip vortex of an optimized 12-bladed conventional propeller.

Copyright © 2019 by ASME
Your Session has timed out. Please sign back in to continue.

References

Larsson, L., Grönstedt, T., and Kyprianidis, K. G., 2011, “Conceptual Design and Mission Analysis for a Geared Turbofan and an Open Rotor Configuration,” ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition, Vancouver, Canada, June 6–10, pp. 359–370.
Patrao, A. C., Avellán, R., Lundbladh, A., and Grönstedt, T., 2016, “Wake and Loss Analysis for a Double Bladed Swept Propeller,” ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition, Seoul, South Korea, June 13–17, pp. V001T01A013.
Patrao, A. C., Grönstedt, T., Avellán, R., and Lundbladh, A., 2018, “Wake Energy Analysis Method Applied to the Boxprop Propeller Concept,” Aerosp. Sci. Technol., 79, pp. 689–700. [CrossRef]
Adkins, C. N., and Liebeck, R. H., 1994, “Design of Optimum Propellers,” J. Propul. Power, 10(5), pp. 676–682. [CrossRef]
Drela, M., 2006, QPROP Formulation, Massachusetts Inst. of Technology Aeronautics and Astronautics, Cambridge, MA.
Negulescu, C. A., 2013, “Airbus AI-PX7 CROR Design Features and Aerodynamics,” SAE Int. J. Aerosp., 6(2), pp. 626–642. [CrossRef]
Avellán, R., Patrao, A. C., Lundbladh, A., and Grönstedt, T., 2015, “Preparing for Proof-of-Concept of a Novel Propeller for Open Rotor Engines,” The 22nd International Symposium on Air Breathing Engines, Phoenix, Arizona, Oct. 25–30, ISABE Paper No. ISABE-2015-20097.
Ellbrant, L., Eriksson, L.-E., and Mårtensson, H., 2012, “Design of Compressor Blades Considering Efficiency and Stability Using CFD Based Optimization,” ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, Copenhagen, Denmark, June 11–15, pp. 371–382.
Ellbrant, L., Eriksson, L.-E., and Mårtensson, H., 2012, “CFD Optimization of a Transonic Compressor Using Multiobjective GA and Metamodels,” Proceedings of the 28th International Congress of the Aeronautical Sciences, Brisbane, Australia, Sept. 23–28, pp. 2698–2712.
Lejon, M., Andersson, N., Grönstedt, T., Ellbrant, L., and Mårtensson, H., 2016, “Optimization of Robust Transonic Compressor Blades,” ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition, Seoul, South Korea, June 13–17, pp. V02CT45A022.
Schnell, R., Yin, J., Voss, C., and Nicke, E., 2012, “Assessment and Optimization of the Aerodynamic and Acoustic Characteristics of a Counter Rotating Open Rotor,” ASME J. Turbomach., 134(6), p. 061016. [CrossRef]
Lepot, I., Leborgne, M., Schnell, R., Yin, J., Delattre, G., Falissard, F., and Talbotec, J., 2011, “Aero-Mechanical Optimization of a Contra-Rotating Open Rotor and Assessment of its Aerodynamic and Acoustic Characteristics,” Proc. Inst. Mech. Eng., Part A, 225(7), pp. 850–863. [CrossRef]
Capitao Patrao, A., Montero Villar, G., Takachi Tomita, J., Bringhenti, C., Avellan, R., Lundbladh, A., and Grönstedt, T., 2016, “An Optimization Platform for High Speed Propellers,” Aerospace Technology Congress 2016, Stockholm, Oct. 11–12.
Saravanamuttoo, H. I. H., 2001, Gordon Frederick Crichton Rogers, and Henry Cohen. Gas Turbine Theory, Pearson Education, Harlow, Essex.
Sullivan, W. E., Turnberg, J. E., and Violette, J. A., 1984, Large-Scale Advanced Prop-Fan (LAP) Blade Design, Hamilton Standard Division, United Technologies, Hamilton Standard; Windsor Locks, CT.
ANSYS Inc., 2012, ANSYS CFX-Solver Modelling Guide, version 14.5.
Deb, K., Pratap, A., Agarwal, S., and Meyarivan, T. A. M. T., 2002, “A Fast and Elitist Multiobjective Genetic Algorithm: NSGA-II,” IEEE Trans. Evol. Comput., 6(2), pp. 182–197. [CrossRef]
Hall, C., Zachariadis, A., Brandvik, T., and Sohoni, N., 2014, “How to Improve Open Rotor Aerodynamics at Cruise and Take-Off,” Aeronaut. J., 118(1208), pp. 1103–1123. [CrossRef]
Denton, J. D., 1993, “Loss Mechanisms in Turbomachines,” ASME 1993 International Gas Turbine and Aeroengine Congress and Exposition, Cincinatti, OH, May 24–27, pp. V002T14A001.
Dixon, S. L., and Hall, C., 2010, Fluid Mechanics and Thermodynamics of Turbomachinery, Butterworth-Heinemann, London.
Miller, R. J., and Denton, J. D., 2012, Loss Mechanisms in Turbomachines, Cambridge Turbomachinery Course, University of Cambridge, Cambridge, UK, pp. 79–116.
Andersson, J., Eslamdoost, A., Patrao, A. C., Hyensjö, M., and Bensow, R. E., 2018, “Energy Balance Analysis of a Propeller in Open Water,” Ocean Eng., 158(2018), pp. 162–170. [CrossRef]
Brandvik, T., Hall, C., and Parry, A. B., 2012, “Angle-of-Attack Effects on Counter-Rotating Propellers at Take-Off,” ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, Copenhagen, Denmark, June 11–15, pp. 523–534.
Van Zante, D. E., Collier, F., Orton, A., Arif Khalid, S., Wojno, J. P., and Wood, T. H., 2014, “Progress in Open Rotor Propulsors: The FAA/GE/NASA Open Rotor Test Campaign,” Aeronaut. J., 118(1208), pp. 1181–1213. [CrossRef]
Capitao Patrao, A., 2017, Implementation of Blade Element Momentum/Vortex Methods for the Design of Aero Engine Propellers, Chalmers University of Technology, Gothenburg.

Figures

Grahic Jump Location
Fig. 1

A conceptual rendering of an open rotor featuring two propeller blade rows. Air flows from left to right, the front rotor is composed of a Boxprop while the rear rotor is a conventional propeller blade.

Grahic Jump Location
Fig. 2

Boxprop with direction of airflow and rotation. Leading (LB) and trailing blades (TB) relative to the direction of rotation are marked.

Grahic Jump Location
Fig. 3

Potential blade interference countermeasures for the Boxprop. Arrows denote the direction that blade halves can be moved. (1) Involves sweeping apart the blade halves along the flow direction, the TB upstream, and LB downstream. (2) Moving the blade halves apart in the tangential direction.

Grahic Jump Location
Fig. 4

The components of the Boxprop optimization platform

Grahic Jump Location
Fig. 5

The stacking line is built up for each blade half separately as is shown in the figure to the left, and they share a common control point (P4) at the tip of the blade, which is constrained to lie on the z-axis. The position of the individual remaining control points is constructed using a displacement angle κi and a blade passage distance parameter di, as shown in the figure to the right. The arrow head of the local undisturbed velocity vector V also coincides with z-axis and is perpendicular to the distance blade passage distance di.

Grahic Jump Location
Fig. 6

Radial distribution of camber. The control points P1P5 are used to construct the Bézier curve which defines the camber distribution.

Grahic Jump Location
Fig. 7

Domain setup for the CFD simulations. Frozen rotor (FR) interfaces connect the inner 3D (white) and outer 2D domain (gray).

Grahic Jump Location
Fig. 9

Control volume for wake analysis. Surface 1 (inflow) is assumed to have uniform properties while the streamsurface S has no mass flux crossing it. A streamline travelling from 1 to 2 has been added to illustrate the work transfer from a propeller blade to the flow.

Grahic Jump Location
Fig. 10

Simulation domain of the cases analyzed with the wake analysis theory. The line to the right of the blade denotes the integration surface used in the wake analysis. Identical boundary conditions are used as for the optimization cases. The downstream frozen rotor interface present in the optimization cases has been removed in this domain setup. Instead, the inner 3D domain has been extended axially downstream all the way to the outlet. Note that the axial extent of the outer 2D domain is not exactly the same as for the optimization cases. The optimization cases used a domain size identical to a previous optimization paper [13], while the wake analysis cases use an outer domain size in line with what was used in a previous Boxprop wake analysis paper [3].

Grahic Jump Location
Fig. 11

Coarsest (9.9M cells) mesh used for the Boxprop wake energy analysis mesh study. The freestream flow direction is aligned with the negative x-axis. As can be seen, the blocks downstream of the blade trailing edge are well refined in order to capture the sharp gradients of the wakes.

Grahic Jump Location
Fig. 12

Results for the aerodynamic optimization of a 6-blade Boxprop. A scaled up legeacy Boxprop (GPX701) propeller simulation from a previous study has been included in order to illustrate the propeller efficiency improvement. A design (BP1112) from the Pareto front with a CT value close to the GPX701 has been re-simulated with a fine mesh (1112_FM) and shows an improvement of 7% in propeller efficiency.

Grahic Jump Location
Fig. 13

Mach number distributions at 75% radius for the legacy GPX701 Boxprop (top) and the optimized BP1112 design (bottom)

Grahic Jump Location
Fig. 14

LB and TB stacking lines for all the cases in the Pareto front of the optimization. The dashed lines are the limits in stacking line positions for the LB and TB resulting from using the min/max values of the chord displacement angle κi and blade passage distance di.

Grahic Jump Location
Fig. 15

Calculated displacement angle κ(r) distribution for each position of the stacking line. Curves in grey denote the displacement angle distributions of each individual Pareto front design, while the thick line denotes the average of the entire Pareto front.

Grahic Jump Location
Fig. 16

LB and TB stacking lines for all the cases in the Pareto front of an optimization with broader variable ranges for the stacking line displacement angle κi and blade passage distance di. The dashed lines are the limits in stacking line positions for the LB and TB resulting from using the min/max values of κi and di.

Grahic Jump Location
Fig. 17

Calculated displacement angle κ(r) distribution for each position of the stacking line for all the cases in the Pareto front of an optimization with broader variable ranges. Curves in grey denote the displacement angle distributions of each individual Pareto front design in the expanded optimization, while the thick line denotes the average of the entire Pareto front.

Grahic Jump Location
Fig. 18

The levels of entropy lost work ϕs, radial kinetic energy ur2/2, swirl kinetic energy uθ2/2, and excess axial kinetic energy (Δux)2/2 for the GPX701 and BP1112. These correspond to the loss terms in Eq. (11) and are integrated on a surface located at a downstream axial distance of 0.05D from the trailing edge at the 75% radius position.

Grahic Jump Location
Fig. 19

Sectional lift distribution along the radius of the blades for the legacy GPX701 Boxprop, optimized BP1112 Boxprop, the 6-bladed conventional propeller, and the 12-bladed conventional propeller

Grahic Jump Location
Fig. 20

Vorticity [1/s] contour plots for the (a) legacy GPX701 Boxprop, (b) optimized BP1112 Boxprop, (c) optimized 6-bladed conventional propeller, and (d) optimized 12-bladed conventional propeller

Grahic Jump Location
Fig. 21

Axial cuts of wake vorticity and vortex streamlines for the BP1112 (upper image) and the optimized 12-bladed conventional propeller (lower image). The axial cuts range downstream axial distances of 0.05D–0.525D from the trailing edge of the blades (at r/R = 0.75).

Grahic Jump Location
Fig. 22

Power fluxes (W/m2) in descending vertical order for the legacy GPX701 Boxprop, BP1112 optimized Boxprop, 6-bladed conventional propeller, and the 12-bladed conventional propeller. The power fluxes represent the fluxes of kinetic energy due to the velocity perturbations and are plotted on planes located 0.2D downstream of the propellers. The displayed values have been scaled with a factor 105.

Grahic Jump Location
Fig. 23

The magnitudes of the various loss sources for the propellers. The losses are presented as percentages of the engine shaft power for each propeller.

Tables

Errata

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In