Experimental Investigation of Propeller Performance with Propeller Surface Corrugations
S. Gowtham Prabhu, S. Azhagarasan, K. Pavithra, G. Sasi
Department of Aeronautical Engineering, Paavai Engineering College, Namakkal.
The propeller is the primary component of flying vehicles powered by electric motors, internal combustion engines, and turboprops for producing thrust. A propeller thrust is produced in the engine by effective spinning of the propeller through air for cost-effective and environmental friendly flight. Natural flyers like birds as well as aquatic animals like humpback whales effectively use its wings and flippers with its surface features for capturing its prey and escaping from their enemies. As part of this work, corrugations are established in the leading edges or in the suction surfaces of the propeller to modify the flow field prevailing over there. Because of the flow field, the surface corrugations or leading edge corrugations energize the boundary layer in the surfaces of the propeller by counter-rotating vortices which, in turn, delays the separation of the boundary layer from the surface. The performance parameters of the propeller such as thrust, torque, propeller efficiency, power consumption etc., are measured using propeller test rig. Depending on the location of surface or leading corrugations, the variations in the performance of the propeller are investigated for further optimization on the selection of better propeller to the applications of UAVs operating at low Reynolds No.
An Unmanned Aerial Vehicles capable of Vertical Take-Off and Landing (VTOL UAVs), are increasingly deployed for various applications like surveillance, autonomous parcel delivery, oil and gas spill detection and firefighting. The event of Unmanned Aerial Vehicles (UAV) for civil and military applications has increased significantly over the last decade. More industries like agricultural, educations, communications, and energy sector are getting more courageous to venture into the utilizations of UAV to carry our various missions. Because the advancement of technologies, the implementation of UAV may contribute to extend in productivity also as reducing the danger, allowing replacement of manned mission [1-3]. This is often because UAVs are cost and maintenance friendly. Hence, it‘s vital to possess high-performance UAV design in order that it could deliver the mission efficiently.
An unmanned aerial vehicle (UAV) is an aircraft without human pilot on board and a type of unmanned aerial vehicle. UAV may be a component of an unmanned aircraft system (UAS); which include a UAV, a ground-based controller, and a system of communications between the two. The flight of UAVs may operate with various degrees of autonomy: either under remote by human operator or by onboard computers. Compared to crewed aircraft, UAVs were originally used for missions too "dull, dirty or dangerous" for humans [4-7]. While they originated in military applications, their use is rapidly expanding to commercial, scientific, agricultural, and other applications, such as policing and surveillance, product deliveries, aerial photography, infrastructure inspections, smuggling, and drone racing. The performance of a UAV is significantly influenced by the efficiency of the propeller. Thus, it’s vital to research the propeller performance to make sure that the planning led to a reliable UAV performance. The performance of a drone or an UAV is predicted on the parameters like thrust, torque and rpm. The performance increases of an UAV without additional amount of power consumption is accessed by generating a corrugation on a number one fringe of a propeller. From the generation of surface corrugation the performance parameters were increased alongside various rpm’s . Generally, propeller used for UAV operates at very low Reynolds number, measured at the 75% chord of the propeller. The method of choosing the simplest propeller could also be tedious, because it must be tested to suit the specification and requirements of the UAV. Additionally, the selections for propeller blade are concentrated to standard blade design. Unconventional blade designs like slotted, serrated, tubercle and adaptive structure are less likely to be implemented because it got to be designed and fabricated independently supported the wants of the flight. Slotted blade designs are proposed during this study to engaged novel blade design implementations for UAV [9-11].
The propellers were fixed within the propeller test rig alongside the adrenal board. Torque, thrust, and propeller speed were all measured using the experimental test rig. As shown in figure 1. The aim of those propeller tests was to seek out the thrust and torque produced at given propeller RPMs. The primary a part of each test is to seek out the RPM range for a propeller. Propeller thrust was measured using the load cell features a capacity of 2kg. Efforts were made to scale back the complexity of the assembly inside the structure, so as to make sure minimal flow and measuring disturbances. The T-shaped pendulum is pivoted about two flexural pivots being constrained by a load cells outside of the test volume within the test rig, where many of room is out there. The flexural pivots are frictionless, stiction-free bearings with negligible hysteresis that are fitted to applications with limited angular travel. The pivots are made with flat, crossed flat springs that support rotating sleeves. Alongside the test rig and adrenal board a computer was connected through a cable. A measured value were transmitted to a computer and therefore the data’s are plotted during a excel sheet. The optimum values are inbuilt it and therefore the best results were plotted during a graph.
Figure 1: Static propeller test rig.
The static test may be a software testing method that involves examination of the program's code and its associated documentation but doesn’t require the program be executed. It’s primarily an checking of the code or manually reviewing the code or document to spot errors. The theory behind this design, which is being experimentally tested, is that the propeller's airflow upstream is slower than the downstream airflow to the propeller. The airflow round the propeller features a cone. The world of the air affected upstream of the propeller is larger and, thanks to the conservation of mass, it’s also slower. Since drag losses are proportional to the square of the speed, an obstacle upstream will features a smaller effect on the thrust than an obstacle downstream. The air moving slower causes less drag losses thanks to the testing equipment, which is why we recommend testing within the configuration of the figure 2. We will always reverse the reading by activating the reverse thrust checkbox of our software in the ”Utilities” tab if we prefer to not need to do that operation in our spreadsheet editor after. Note that your quadcopter arm or airframe also will have an impression on the thrust in UAV.
Figure 2: Propeller in the test rig with surface corrugations.
RESULT AND DISCUSSION
The experiments have been performed for investigating the static performance of the gas and glow (APC brand) propeller with and without heading edge modifications illustrates in figure 3. The performance parameters such as thrust, torque and propeller efficiency have been measured in the propeller test rig for different type propellers with constant diameter and varying pitch vice versa. By inspiring the maneuvers done by humpback whales, the leading edge flippers like structures are incorporated in the hub or in the tip to study its capability in increasing thrust and propeller efficiency without increasing the torque. Figure 4 and 5 illustrates the variation of propeller efficiency with rotated speed of the propeller with and without leading edge modifications with increase in rotational speed of the propeller, the thrust, and torque increases for all the propeller combinations studied here. At the same time, the propeller efficiency initially shows a drastic increase for increase in rotational speed is in line with the similar variation reported in the literatures.
Figure 3: Propeller with leading edge surface corrugations
By introducing a leading edge flippers near the tip of the propeller the thrust and propeller efficiency shows lower magnitude but torque does not show any change in magnitude than the propeller without any leading edge flipper. At the same time, the thrust and propeller efficiency has higher magnitude without increasing the torque required for running the propeller while introducing flippers near the hub of the propellers.
Figure 4: Propeller speed vs. propeller efficiency on 7×4 propeller dimensions
Figure 5: Propeller speed vs. propeller efficiency on 7×9 propeller dimensions
However, while increasing the number of flippers near the hub of the propeller, the thrust and propeller efficiency has lower magnitude than the propeller without any leading edge flippers. The increment in performance of the propeller has been mainly attributed to the counter rotating vortices formed due to the leading edge flippers lower the speed near the hub of the propeller are effective in harnessing effect of counter rotating vortices. At the same, the blade speed is very high at the tip which in turn creating instability within counter rotating vortices. This results in reducing the magnitude of the performance parameters. The experimental testing of the propeller performance study proves the performance of the propeller can be increased by introducing leading edge flipper near the hub of the propeller.
This paper addressed a propeller's production and validation, suitable for testing a large range of low Reynolds number propellers up to a diameter of about 7”. The surface corrugations in the leading edge of a propeller will increases the performance of an UAV with normal power consumption. Furthermore, the performance of gas and glow propellers was measured over a range of different rotational speeds. It was shown that as the increases of performance with the increase of propeller rpm, the propellers performance is significantly affected by increasing their thrust coefficient and efficiency.
1. Moore K., and Ning, A., ‘Aerodynamic Performance Characterization of Leading Edge Protrusions on Small Propellers’, AIAA Aerospace Sciences Meeting, San Diego, CA, Jan. 2016.
2. A Seeni.. A Critical Review on Tubercles Design for Propellers. IOP Conf. Series: Materials Science and Engineering.. 370; 2015: 012015.
3. John B. Brandt and Michael S., ‘Propeller Performance Data at Low Reynolds Numbers’, AIAA Aerospace Sciences Meeting AIAA January 2011, Orlando.
4. M. F. Shariff., ‘Propeller Aerodynamic Analysis and Design’ School of Aerospace, Mech. & Manufacturing Eng., RMIT University, 2017.
5. Arun Prakash J, Sweta S Radhakrishnan, Ramavijay N, Vishnupriya S., ‘Experimental investigation of stepped aerofoil using propeller test rig’, IJRET: International Journal of Research in Engineering and Technology, 2017.
6. Donghun Park, Yunggyo Lee, Taehwan Cho and Cheolwan Kim., ‘Design and Performance Evaluation of Propeller for Solar-Powered High-Altitude Long-Endurance Unmanned Aerial Vehicle’, Hindawi International Journal of Aerospace Engineering Volume 2018.
7. Yuchuan Zhang, Zhiqiang Hu, Yi Yang Lingbo Geng, Chao Wang., ‘A Performance Analysis Method of High Speed and Small Diameter Propeller’, IOP Conf. Series: Materials Science and Engineering, 2018.
8. Robert W. Deters and Michael S. Selig., ‘Static Testing of Micro Propellers’, 26th AIAA Applied Aerodynamics Conference 18 - 21 August 2008, Honolulu, Hawaii.
9. Yuying Xia, Onur Bilgen and Michael I Friswell., ‘The effect of corrugated skins on aerodynamic performance’, Journal of Intelligent Material Systems and Structures, February 2014.
10. M Khasyofi and F Hartono., ‘Development Testing Method and Analysis Static Thrust for Propeller Based Propulsion’, IOP Conf. Series: Materials Science and Engineering 2019.
11. C. Thill, J.A. Etches, I.P. Bond, K.D. Potter and P.M. Weaver., ‘Corrugated composite structures for aircraft morphing skin applications’, 18th International Conference of Adaptive Structures and Technologies, October 2007 Ottawa, Ontario, Canada.
Received on 19.06.2021 Accepted on 06.07.2021
©A&V Publications all right reserved
Research J. Engineering and Tech. 2021;12(2):39-43.