Significant Drag Reduction Research Articles

Tribological Behavior of Bioinspired Surfaces

Energy losses due to various tribological phenomena pose a significant challenge to sustainable development. These energy losses also contribute toward increased emissions of greenhouse gases. Various attempts have been made to reduce energy consumption through the use of various surface engineering solutions. The bioinspired surfaces can provide a sustainable solution to address these tribological challenges by minimizing friction and wear. The current study majorly focuses on the recent advancements in the tribological behavior of bioinspired surfaces and bio-inspired materials. The miniaturization of technological devices has increased the need to understand micro- and nano-scale tribological behavior, which could significantly reduce energy wastage and material degradation. Integrating advanced research methods is crucial in developing new aspects of structures and characteristics of biological materials. Depending upon the interaction of the species with the surrounding, the present study is divided into segments depicting the tribological behavior of the biological surfaces inspired by animals and plants. The mimicking of bio-inspired surfaces resulted in significant noise, friction, and drag reduction, promoting the development of anti-wear and anti-adhesion surfaces. Along with the reduction in friction through the bioinspired surface, a few studies providing evidence for the enhancement in the frictional properties were also depicted.

Manipulation of the aerodynamic behavior of the DrivAer model using dimple patterns

Societies rising environmental awareness in the context of advancing climate change is continuously shifting the focus of automotive development to vehicle efficiency and thus also to aerodynamic resistance. However, customers favor the familiar vehicle aesthetics, so research and development must find new solutions to reduce drag based on a given body shape. Dimple patterns extruded outward from the vehicle skin are considered in this study with the aim of reducing flow separation and thus lowering drag. They are applied to the realistic and already optimized notchback DrivAer vehicle model. Delayed detached-eddy simulations validated by experiments are used to assess the potential of this concept. In order to see the dependence of the concept on essential parameters, the location, size as well as height of the dimple pattern are varied in this study. All applied patterns on the rear window of the DrivAer model reduce drag and lift by up to 1.9% and 19.2%, respectively, compared to the reference geometry without dimple pattern. A large-scale dimple pattern is less sensitive with respect to the dimple height, whereas a smaller pattern exhibits more significant variations with respect to drag and downforce as the dimple height is varied. Compared to conventional vortex generators, the dimple pattern approach shows less potential to increase downforce, but allows a significant reduction in drag compared to the classical approach, with the consequence of increasing efficiency and reducing emissions.

Mechanisms of Morphing Wall Flow Control by Traveling Waves over an Airfoil

The main two mechanisms of morphing wall flow control are direct injection of momentum in the streamwise direction and indirect momentum transfer via triggering instabilities. Traveling waves have been shown to perform better than standing waves, probably because they can use both mechanisms. However, the relative importance of the two mechanisms is not known. To differentiate between the mechanisms, a range of parameters (frequency, amplitude, and starting location) at stall (15 deg angle of attack) and poststall (20 deg angle of attack) is tested using wall-resolved large-eddy simulations with a sharp-interface curvilinear immersed boundary method at a low Reynolds number of over a NACA0018 airfoil. The results of the simulations demonstrate that the flow is reattached within a range of nondimensional frequencies, actuation amplitudes, and starting locations of oscillation at the stall and poststall angles of attack. Significant lift enhancement and drag reduction are also observed within these ranges. The nondimensional frequency range at which the flow is reattached is found to be similar to the dominant nondimensional frequencies of leading-edge vortex shedding of the unactuated airfoil. These indicate that the indirect transfer of momentum is the dominant mechanism because direct injection of momentum increases with the increase of amplitude and frequency; that is, separation should reduce as they increase. Nevertheless, direct injection of momentum improves the performance relative to pure excitations of standing waves when instabilities are triggered.

Deep Reinforcement Learning for Flow Control Exploits Different Physics for Increasing Reynolds Number Regimes

The increase in emissions associated with aviation requires deeper research into novel sensing and flow-control strategies to obtain improved aerodynamic performances. In this context, data-driven methods are suitable for exploring new approaches to control the flow and develop more efficient strategies. Deep artificial neural networks (ANNs) used together with reinforcement learning, i.e., deep reinforcement learning (DRL), are receiving more attention due to their capabilities of controlling complex problems in multiple areas. In particular, these techniques have been recently used to solve problems related to flow control. In this work, an ANN trained through a DRL agent, coupled with the numerical solver Alya, is used to perform active flow control. The Tensorforce library was used to apply DRL to the simulated flow. Two-dimensional simulations of the flow around a cylinder were conducted and an active control based on two jets located on the walls of the cylinder was considered. By gathering information from the flow surrounding the cylinder, the ANN agent is able to learn through proximal policy optimization (PPO) effective control strategies for the jets, leading to a significant drag reduction. Furthermore, the agent needs to account for the coupled effects of the friction- and pressure-drag components, as well as the interaction between the two boundary layers on both sides of the cylinder and the wake. In the present work, a Reynolds number range beyond those previously considered was studied and compared with results obtained using classical flow-control methods. Significantly different forms of nature in the control strategies were identified by the DRL as the Reynolds number Re increased. On the one hand, for Re≤1000, the classical control strategy based on an opposition control relative to the wake oscillation was obtained. On the other hand, for Re=2000, the new strategy consisted of energization of the boundary layers and the separation area, which modulated the flow separation and reduced the drag in a fashion similar to that of the drag crisis, through a high-frequency actuation. A cross-application of agents was performed for a flow at Re=2000, obtaining similar results in terms of the drag reduction with the agents trained at Re=1000 and 2000. The fact that two different strategies yielded the same performance made us question whether this Reynolds number regime (Re=2000) belongs to a transition towards a nature-different flow, which would only admits a high-frequency actuation strategy to obtain the drag reduction. At the same time, this finding allows for the application of ANNs trained at lower Reynolds numbers, but are comparable in nature, saving computational resources.

Effect of anisotropic resistance characteristic on boundary-layer transitional flow

It is observed that the feather surface exhibits anisotropic resistances for the streamwise and spanwise flows. To obtain a qualitative understanding about the effect of this anisotropic resistance feature of surface on the boundary-layer transitional flow over a flat plate, a simple phenomenological model for the anisotropic resistance is established in this paper. By means of the large eddy simulation (LES) with high-order accurate finite difference method, the numerical investigations are conducted. The numerical results show that with the spanwise resistance hindering the formation of vortexes, the transition from laminar flow to turbulent flow can be delayed, and turbulence is weakened when the flow becomes fully turbulent, which leads to significant drag reduction for the plate. On the contrary, the streamwise resistance renders the flow less stable, which leads to the earlier transition and enhances turbulence in the turbulent region, causing a drag increase for the plate. Thus, it is indicated that a surface with large resistance for spanwise flow and small resistance for streamwise flow can achieve significant drag reduction. The present results highlight the anisotropic resistance characteristic near the feather surface for drag reduction, and shed a light on the study of bird’s efficient flight.

Aqueous Solutions of Associating Poly(acrylamide-co-styrene): A Path to Improve Drag Reduction?

Hydrophobically modified associating polymers could be effective drag-reducing agents containing weak "links" which after degradation can reform, protecting the polymer backbone from fast scission. Previous studies using hydrophobically modified polymers in drag reduction applications used polymers with M w ≥ 1000 kg/mol. Homopolymers of this high M w already show significant drag reduction (DR), and the contribution of macromolecular associations on DR remained unclear. We synthesized associating poly(acrylamide-co-styrene) copolymers with M w ≤ 1000 kg/mol and various hydrophobic moiety content. Their DR effectiveness in turbulent flow was studied using a pilot-scale pipe flow facility and a rotating "disc" apparatus. We show that hydrophobically modified copolymers with M w ≈ 1000 kg/mol increase DR in pipe flow by a factor of ∼2 compared to the unmodified polyacrylamide of similar M w albeit at low DR level. Moreover, we discuss challenges encountered when using hydrophobically modified polymers synthesized via micellar polymerization.

Insights from molecular simulations on liquid slip over nanostructured surfaces.

The current study focuses on non-equilibrium molecular dynamics (NEMD) simulations to investigate the slip properties of water flowing over different nanostructured surfaces. A simulation protocol is developed that applies constant shear stress throughout the fluid before measuring the slip length. Using pseudo-data, the reliability of this protocol in terms of both accuracy and noise of the results for high-slip and multiphase systems is demonstrated. In contrast to the NEMD techniques available in the literature, the protocol also enables a convenient way to compare the slip lengths of different surface coatings. The fluid slip lengths of surface coatings comprising carbon nanotubes on platinum are predicted using the proposed protocol with nitrogen gas trapped in the interstitial gaps. The role of these gas pockets in determining surface slip properties is investigated. The NEMD results from the proposed model compare well with a macroscopic theoretical model for nano-patterned surfaces. Finally, it is concluded that entrapped gas within nanostructures may offer significant drag reduction only if the gas surface coverage is above 95%.

Passive Drag Reduction of the Square Back Truck Body

Drag is one of the most significant factors that increase fuel consumption, followed by operating cost of the vehicle. Square-back road vehicles like trucks and buses are common and popular means of transport across the globe. In this background, it is of great research value to reduce the drag on vehicles, improve their fuel efficiency and reduce their operational cost. In this work, a simplified model of a truck was considered, and its drag was reduced by modifying its geometry using passive drag reduction devices. The passive devices used in this study were backward-facing step, fins, splitter plates/tabs, dimple, vents, and channels. These devices, of different sizes and configurations, were numerically studied using CFD software Star CCM+ at a Reynolds number of 2.4127×10^6. Drag reduction up to 9.9% was achieved, when backward-facing step was placed at the bottom rear edge of the truck. Further, multiple circular channels used on the truck’s sides reduced the drag up to 6.5%, while multiple rectangular channels on the sides of the truck achieved 5.1% drag reduction. The maximum drag reduction of the fins was found to be 4.6%. In spite of these, no significant drag reduction was observed when using splitter plates/tabs, dimple and vents.

Experimental Investigation of Turbulent Cross-flow in a Staggered Tube Bundle with Wavy Cylinders

This paper presents the results of an investigation on the effects of wavy cylindrical tubes on the turbulent cross-flow in a staggered tube bundle arrangement with transverse and longitudinal pitch-to-diameter ratios of 3.8 and 2.1, respectively. Two models of staggered tube bundles equipped with wavy cylinders are tested; the Model-A having a wavelength ratio (λ/DSUBm/SUB= 2) corresponding to a wave steepness (a/λ = 0.1) and the Model-B having (λ/DSUBm/SUB= 1) corresponding to (a/λ= 0.2).Experimental measurements were performed using a subsonic wind tunnel to study and compare the flow characteristics of the new configuration of cylindrical tubes with that of a similar arrangement with smooth cylinders for Reynolds numbers ranging from 0.5×10⁴ to 2×10⁴ based on the mean tube diameter and the free stream velocity. Experimental results show that the circumferential minimum pressure coefficients for wavy tube bundles are greater than at the bundle with smooth cylinders. As a result, the lift forces of wavy tube bundles are suppressed and a significant drag reduction is observed up to 20% for both wavy models. This continuous reduction of the drag force becomes larger with the increase of Reynolds number.

Flexible surfaces prepared through direct ink writing with drag reduction and antifouling

The riblet structure on the surface of the shark skin provides significant drag reduction and fouling protection. Inspired by the structure of the shark skin, we present a direct ink writing protocol by modifying the rheological properties of polydimethylsiloxane to make it printable, and a series of flexible surfaces have been created with drag reduction and antifouling. The shear stress transport k–omega model was used as a suitable turbulence model for the numerical study to compare with results of drag reduction tests. Simulations and tests proved that printed non-smooth surfaces effectively reduced water drag, where the maximum drag reduction rate reached 18.16 % at 0.06 m/s. Through the analysis of the characteristics of the flow field near the wall, the drag reduction mechanism of the riblet surface was examined. Moreover, the antifouling tests revealed that the printed surface exhibited excellent fouling resistance and inhibited the spread of dirt on the surface. Our findings may provide a new surface skinning strategy for ships, underwater vehicles and wearable devices to reduce drag and contaminant adhesion and improve navigation efficiency and longevity.

Effects of Stroke Amplitude and Wing Planform on the Aerodynamic Performance of Hovering Flapping Wings

In this paper, the effects of stroke amplitude and wing planform on the aerodynamics of hovering flapping wings are considered by numerically solving the incompressible Navier–Stokes equations. The wing planform geometry is represented using a beta-function distribution for an aspect ratio range of 3–6 and a dimensionless radial centroid location range of 0.4–0.6. Typical normal hovering kinematics has been employed while allowing both translational and rotational durations to be equally represented. The combined effects of stroke amplitude with wing aspect ratio and radial centroid location on the aerodynamic force coefficients and flow structures are studied at a Reynolds number of 100. It is shown that increasing the stroke amplitude increases the translational lift for either small aspect ratio or large radial centroid location wings. However, for high aspect ratio or low radial centroid location wings, increasing the stroke amplitude leads to higher lift coefficients during the translational phase only up to a stroke amplitude of 160°. Further increase in stroke amplitude results in reduced translational lift due to the increased wingtip stall effect. For all the cases considered, the lift and drag coefficients of the rotational phase decrease with the increase of stroke amplitude leading to decreased cycle-averaged force coefficients. Furthermore, it is found that the significant reduction in the rotational drag as the stroke amplitude increases leads to a consistently increasing aerodynamic efficiency against stroke amplitude for all aspect ratio and radial centroid location cases.

Experimental research on aero-propulsion coupling characteristics of a distributed electric propulsion aircraft

Distributed Electric Propulsion (DEP) aircraft use multiple electric motors to drive the propulsors, which gives potential benefits to aerodynamic-propulsion interaction. To investigate and quantify the aerodynamic-propulsion interaction effect of the wing section, we built a DEP demonstrator with 24 “high-lift” Electric Ducted Fans (EDFs) distributed along the wing’s trailing edge. This paper explores and compares the aero-propulsion coupling characteristics under various upstream speed, throttle, and EDF mounting surface deflection angles using a series of wind tunnel tests. We compare various lift-augmentation power conditions to the clean configuration without propulsion unit under the experiment condition of 15–25 m/s freestream flow and angles of attack from −4° to 16°. The comparison of computational results to the experimental results verifies the effectiveness of the computational fluid dynamic analysis method and the modeling method for the DEP configuration. The results show that the EDFs can produce significant lift increment and drag reduction simultaneously, which is accordant with the potential benefit of Boundary Layer Ingestion (BLI) at low airspeed.

Thermodynamic analysis of counter flow injection

Present computational investigation is carried out to reveal the effect of jet and freestream parameters on flow field alteration and associated properties. Further, thermodynamic analysis is also performed to account the irreversibilities in lower and higher enthalpy flows and various opposing conditions with real gas effects. In this regard, a computationally efficient non-equilibrium real gas solver is developed which accounts five species and eleven chemical elementary reactions. After validation of this solver, simulations are performed for various parameters of jet and freestream to examine the real gas effect on flow field and different thermodynamic parameters such as entropy generation rate, exergy destruction etc. The computed result reveals that freestream parameters have minor effect on drag coefficient and flow field but there is monotonic variation in entropy generation rate and exergy destruction for constant momentum ratio of the jet. For given momentum ratio, jet parameters give small reduction in entropy generation rate and exergy destruction while minor alterations in flow field and drag coefficient are observed. Linear reduction in drag coefficient and sharp rise in entropy generation rate and exergy destruction is obtained with momentum ratio of the jet. These proposed thermodynamic parameters and drag coefficient portrayed opposite variation with given freestream or jet parameter for constant jet momentum ratio. Jet momentum ratio is noted to be the major governing parameter for the extent of jet penetration in the freestream flow which restructures the shock wave and recirculation zone resulting in significant drag reduction and flow field alterations for hypersonic reacting flows as well. Larger shock stand-off distance for higher jet momentum ratio gives lesser drag but results in higher entropy generation rate and exergy destruction which makes the process much more irreversible.

Dynamics of a rigid-flexible coupling system in a uniform flow

Dynamics of two-dimensional flow past a rigid flat plate with a trailing closed flexible filament acting as a deformable afterbody are investigated numerically by an immersed boundary-lattice Boltzmann method for the fluid flow and a finite element method for the filament motion. The effects of Reynolds number ( $Re$ ) and length ratio ( $Lr$ ) on the flow patterns and dynamics of the rigid-flexible coupling system are studied. Based on our numerical results, five typical state modes have been identified in $Lr\unicode{x2013}Re$ plane in terms of the filament shape and corresponding dynamics, i.e. static deformation, micro-vibration, multi-frequency flapping, periodic flapping and chaotic flapping modes, respectively. Benefiting from the passive flow control by using the flexible filament as a deformable afterbody, the coupled system may enjoy a significant drag reduction (up to $22\,\%$ ) compared with bare plate scenarios ( $Lr=1$ ). Maximum drag reduction achieved at $L_{c,{min}} \in [1.8, 2]$ is often accompanied by the onset of the system state transition. The flow characteristic and its relation to the change in hydrodynamic drag are further explored in order to reveal the underlying mechanisms of the counterintuitive dynamical behaviour of the coupled system. The scaling laws for the form drag and the friction drag, which arise from the pressure and viscous effects, respectively, are proposed to estimate the overall drag acting on the system. The results obtained in the present study may shed some light on understanding the dynamical behaviour of rigid-flexible coupling systems.

Control of Dynamic Stall on Swept Finite Wings

A low-amplitude high-frequency flow control strategy for mitigation of transient tip stall is demonstrated for the case of a finite swept wing using high-fidelity wall-resolved large-eddy simulations. A wing of aspect ratio and NACA 0012 section is considered at freestream Mach number and chord Reynolds number . The wing undergoes an oscillatory pitching motion with reduced frequency and angle of attack between and 22 deg, resulting in deep dynamic tip stall for the uncontrolled case. Spanwise uniform low-amplitude pulsed forcing is imparted through a zero-net mass flow blowing/suction slot located on the wing lower surface near the leading edge using both moderate and high frequencies, and 50, respectively. The imposed small fluctuations are amplified through the natural receptivity of the laminar separation bubble (LSB) and, in the case of the highest frequency, completely inhibit its bursting along the wing, which precludes outboard flow separation and subsequent dynamic tip stall. The lower-frequency forcing cannot overcome eventual bursting of the LSB near the wingtip; however, the resulting separation is localized to the tip region unlike the full outboard unloading of the uncontrolled case. Conditioning of the leading-edge flow through targeted manipulation of the LSB and its inherent dynamics maintained or enhanced the effectively attached flow throughout the pitching cycle, resulting in significant reductions in the cycle-averaged drag and in the force and moment excursions.

The effect of trip wire on transition of boundary layer on a cylinder

The effect of height of a trip and its location on the transition of boundary layer on a cylinder is studied using large eddy simulations for 2×103≤Re≤5×105. The Reynolds number, Re, is based on the free stream speed and diameter of the cylinder (D). Two modes of transition are observed: (a) natural, for a relatively small trip of height dT/D=0.25%, via formation of a laminar separation bubble (LSB) and (b) direct, for a large trip of height dT/D=1.0%, wherein the formation of LSB is bypassed and the trip disturbs the flow enough to cause separation of the boundary layer and its subsequent turbulent reattachment. Transition delays the final separation leading to a very significant reduction in drag, often referred to as drag crisis. The delay is more for natural as compared to direct transition. Consequently, the drag at the end of crisis is lower for natural transition. The 1.0% trip at 78° leads to a more delayed flow separation than one at 55° from the front stagnation point. The drag crisis takes place in two stages for a cylinder with trip. During each of the two stages, asymmetric transition on the two sides results in generation of circulation and lift force. The effect of trip is felt even by the non-trip side. The cylinder experiences a relatively large “reverse lift” during the second stage of drag crisis. While natural transition is accompanied by intermittency of LSB, direct transition is associated with intermittency in laminar vs turbulent attachment of the flow following its separation at the trip.

Bioinspired drag reduction surfaces via triple lithography method based on three-layer hybrid masks

Drag reduction is a significant challenge for many industries, such as ships, pipelines, aircraft, energy, and transportation. Multilayer hierarchical microstructures can inhibit the development of vortices near the wall, which is beneficial to drag reduction. However, existing methods have difficulty performing the controlled fabrication of complex multilayer hierarchical microstructure arrays. Here, a novel triple lithography method based on three-layer hybrid masks is proposed for the controlled fabrication of three-dimensional multilayer hierarchical microstructure surfaces. The capability of the proposed process is verified by the multilayer hierarchical microstructures. In the fabrication process, a special lithography sequence is designed based on the hybrid mask materials. The drag reduction ability of the multilayer hierarchical microstructures is investigated in a closed air channel measurement system. The experimental results demonstrate that the fabricated multilayer hierarchical microstructures exhibit significant drag reduction ability under certain conditions. Conceptual models based on the fluid-solid coupling interface interaction are proposed to explain the drag reduction mechanism of multilayer hierarchical microstructures. The proposed fabrication method provides a powerful means for practical engineering applications of various bioinspired functional surfaces, such as drag reduction, anti-icing, antifouling, self-cleaning, and superhydrophobic surfaces.

An Investigation of Aerodynamic Characteristics of Two Bluff Bodies in Close Longitudinal Proximity – Sensitivity to Front-End Geometry

<div class="section abstract"><div class="htmlview paragraph">With an increasing focus on the reduction of greenhouse gases by the transport industries and continued development of connected and autonomous vehicle systems, the potential for aerodynamic drag reduction by means of managed systems of vehicles travelling in close-proximity, termed “platooning”, has continued as topic for research. Early-work in passenger-car platooning was conducted by varying the spacing between vehicles in homogeneous platoons. More recently the use of systematic changes in upper-body geometry has provided data for another variable in the assessment of platooning characteristics. The results of the investigation described in this paper adds to previously published platooning results using the Windsor reference model. For this investigation a new add-on geometry to the standard nose was designed to provide a simplified bonnet feature. This was chosen in order to vary the on-set flow approaching the platoon and also to influence the flow in the gap between test models. As previously found, the close-proximity presence of a following model resulted in significant drag reductions for the lead model due to wake suppression. Based on drag accumulation analyses in CFD, the “shielding” effect provided by the lead model gave a more significant drag reduction on the front of the following model when fitted with the bonnet addition compared to the standard nose. But the beneficial acceleration of the flow around the A-pillars of the following model was negated resulting in small total drag increases. As in previous investigations, one significant observation was that none of the upper-body geometries was found to be optimal in every position and combination of models.</div></div>

Deep reinforcement learning based synthetic jet control on disturbed flow over airfoil

This paper applies deep reinforcement learning (DRL) on the synthetic jet control of flows over an NACA (National Advisory Committee for Aeronautics) 0012 airfoil under weak turbulent condition. Based on the proximal policy optimization method, the appropriate strategy for controlling the mass rate of a synthetic jet is successfully obtained at Re=3000. The effectiveness of the DRL based active flow control (AFC) method is first demonstrated by studying the problem with constant inlet velocity, where a remarkable drag reduction of 27.0% and lift enhancement of 27.7% are achieved, accompanied by an elimination of vortex shedding. Then, the complexity of the problem is increased by changing the inlet velocity condition and reward function of the DRL algorithm. In particular, the inlet velocity conditions pulsating at two different frequencies and their combination are further applied, where the airfoil wake becomes more difficult to suppress dynamically and precisely; and the reward function additionally contains the goal of saving the energy consumed by the synergetic jets. After training, the DRL agent still has the ability to find a proper control strategy, where significant drag reduction and lift stabilization are achieved, and the agent with considerable energy saving is able to save the energy consumption of the synergetic jets for 83%. The performance of the DRL based AFC proves the strong ability of DRL to deal with fluid dynamics problems usually showing high nonlinearity and also serves to encourage further investigations on DRL based AFC.

Turbulent Drag Reduction with an Ultra-High-Molecular-Weight Water-Soluble Polymer in Slick-Water Hydrofracking.

Water-soluble polymers as drag reducers have been widely utilized in slick-water for fracturing shale oil and gas reservoirs. However, the low viscosity characteristics, high operating costs, and freshwater consumption of conventional friction reducers limit their practical use in deeper oil and gas reservoirs. Therefore, a high viscosity water-soluble friction reducer (HVFR), poly-(acrylamide-co-acrylic acid-co-2-acrylamido-2-methylpropanesulphonic acid), was synthesized via free radical polymerization in aqueous solution. The molecular weight, solubility, rheological behavior, and drag reduction performance of HVFR were thoroughly investigated. The results showed that the viscosity-average molecular weight of HVFR is 23.2 × 106 g⋅mol−1. The HVFR powder could be quickly dissolved in water within 240 s under 700 rpm. The storage modulus (G′) and loss modulus (G″) as well as viscosity of the solutions increased with an increase in polymer concentration. At a concentration of 1700 mg⋅L−1, HVFR solution shows 67% viscosity retention rate after heating from 30 to 90 °C, and the viscosity retention rate of HVFR solution when increasing CNaCl to 21,000 mg⋅L−1 is 66%. HVFR exhibits significant drag reduction performance for both low viscosity and high viscosity. A maximum drag reduction of 80.2% is attained from HVFR at 400 mg⋅L−1 with 5.0 mPa⋅s, and drag reduction of HVFR is 75.1% at 1700 mg⋅L−1 with 30.2 mPa⋅s. These findings not only indicate the prospective use of HVFR in slick-water hydrofracking, but also shed light on the design of novel friction reducers utilized in the oil and gas industry.