P ll d D d F Propellers and Ducted Fans
Transcription
P ll d D d F Propellers and Ducted Fans
PEMP RMD510 P Propellers ll and d Ducted D dF Fans Session delivered by: Prof Q. Prof. Q H. H Nagpurwala 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 1 To help protect y our priv acy , PowerPoint prev ented this external picture from being automatically downloaded. To download and display this picture, click Options in the Message Bar, and then click Enable external content. Session Objectives PEMP RMD510 In this hi session i the h delegates d l would ld learn l about b Types of propellers and ducted fans Working principle of propellers Slip stream, momentum and blade element theories Design procedure for propellers 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 2 Introduction - Propeller PEMP RMD510 A propeller is a device which transmits power by converting it into thrust for propulsion of a vehicle though a fluid by rotating two or more twisted blades about a central shaft, in a manner analogous to rotating a screw through a solid. The blades of a propeller act as rotating wings and produce force through application of Newton's third law of motion, generating a difference in pressure between the forward and rear surfaces of the airfoil-shaped airfoil shaped blades. Air propeller 08 Marine propeller @ M.S. Ramaiah School of Advanced Studies, Bengaluru 3 Application of Propeller PEMP RMD510 P-51 Mustang Toy aircraft Ch Cheyenne EN02 Pilatus Aircraft 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 4 Introduction – Ducted Fan 08 PEMP RMD510 A ducted d t d fan f is i a propulsion l i arrangementt whereby h b a propeller ll is i mounted t d within ithi a cylindrical shroud or duct. The duct prevents losses in thrust from the tips of the propeller and if the duct has an airfoil cross-section, cross section it can provide additional thrust of its own. own Ducted fan propulsion is used in aircrafts, airboats and hovercrafts. In aircraft application, ducted fans normally have more number of shorter blades than propellers and thus can operate at higher rotational speeds. The operating speed of an unshrouded propeller is limited since tip speeds approach the sound barrier at lower speeds than an equivalent ducted propeller. @ M.S. Ramaiah School of Advanced Studies, Bengaluru 5 Application of Ducted Fan Edgley EA7 Optica Bell X-22A 08 PEMP RMD510 DOAK VZ-4 Piasecki VZ-8P(B) @ M.S. Ramaiah School of Advanced Studies, Bengaluru 6 Types of Ducted Fans PEMP RMD510 Duct shapes Accelerating shroud Decelerating shroud Flow Fl decelerating shroud - noise reduction. accelerating shroud - low speed heavily loaded propellers (improves efficiency) Ducted fans are favoured in VTOL and other low-speed designs for their high thrustto eight ratio. to-weight ratio 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 7 PEMP RMD510 Types of Ducts – Based on Mounting 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 8 Slip Stream Theory PEMP RMD510 Continuity equation m 1 A1V1 4 A4V4 Thrust generated T m V1 Power required P TV1 m = mass flow rate in kg/s T = thrust in N P = power in i Watts W tt A = area in m2 V = velocity in m/s = density in kg/m3 08 Froude analysis of propeller @ M.S. Ramaiah School of Advanced Studies, Bengaluru 9 PEMP RMD510 Slip Stream Theory – Unducted Propeller Cruise condition 08 Static St ti condition diti @ M.S. Ramaiah School of Advanced Studies, Bengaluru 10 Slip Stream Theory – Ducted Propeller cruise condition 08 PEMP RMD510 static t ti condition diti @ M.S. Ramaiah School of Advanced Studies, Bengaluru 11 Lift distribution - Propeller Blade Tip relieving effect Unducted propeller 08 PEMP RMD510 Duct friction effect Ducted propeller @ M.S. Ramaiah School of Advanced Studies, Bengaluru 12 Ducted Fan Shape 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru PEMP RMD510 13 Propellers PEMP RMD510 Propeller consists of a number of rotating wings of airfoil shape, designed to convert torque into i thrust. h Very similar to an aircraft wing, the propeller blades are subjected to the same aerodynamic d i laws l andd influences. i fl Velocity Triangle V1 Vr1 U 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 14 PEMP RMD510 Momentum Theory The momentum theory, developed in 1865 by Rankine, is based on the assumption that the propeller functions as a uniform “actuator disk” Flow Thrust Flow Flow Far in front of the actuator disk, the pressure (p) and the air velocity (V) are considered the same as in free air. 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 15 Momentum Theory (… contd.) PEMP RMD510 Assumptions for momentum theory The flow is assumed to be inviscid and incompressible. All rotation of fluid within the stream tube is neglected. The flow velocity is assumed uniform over each cross section of the stream tube. The pressure is assumed uniform over each cross section of the stream tube. By applying conservation of mass, momentum and energy, one can derive the following relations: Thrust T 2 Ap V Vi Vi Brake a e Power owe P 2 Ap V Vi Vi 2 V2 T V Ind ced Velocity Induced Velocit Vi 4 2 Ap 2 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 16 PEMP RMD510 Momentum Theory (… contd.) Brake power can also be expressed as 2 V V T P T 2 4 2 Ap Propulsive efficiency for the propeller TV 2 Ap V Vi ViV V 1 i 2 P 2 Ap V Vi Vi V Vi 1 Vi 1 1 T 2 2 4 2 A V p 08 V 1 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 17 PEMP RMD510 Momentum Theory (… contd.) The Advance Ratio, J ; Thrust Coefficient, CT ; Torque Coefficient, CQ ; and Power Coefficient, CP are defined as: V V J N .d p 2 . d p Q CQ N 2 d 5p CT CP T 2 2 d p4 P 2 d 5p 3 2 J J 2 C T Power coefficient can also be given by C P CT 2 4 and the p propulsive p efficiency y by y 08 CT J 1 1 2CT i CP 2 4 J2 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 1 18 Momentum Theory (… contd.) PEMP RMD510 Limitations of momentum theory Does not account for rotation of the fluid within the slipstream There is no physical basis for neglecting slipstream rotation The actual thrust and propulsive efficiency are lower as a result of slipstream rotation The assumptions of uniform flow and uniform pressure result in a one dimensional solution that is not consistent with the results predicted from propeller vortex theory 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 19 Blade Element Theory PEMP RMD510 In 1878 William Froude developed the blade element theory. This theory is based on the calculation of thrust and torque of a number of sections on the propeller blades. Integration over the entire blade length provides total thrust and torque of the h propeller. ll 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 20 PEMP RMD510 Blade Element Theory (… contd.) The resultant air speed VR r 2 V 2 Where r = Part of propeller radius Ω = angular velocity [rad/s] V The helix angle, a tan r A large pitch (stagger) angle at the root of the blade and a small pitch angle at the tip will ensure an efficient angle of attack over the entire propeller blade. blade The variation in pitch angle from hub to tip results in twisted blades. 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 21 Blade Element Theory (… contd.) PEMP RMD510 When the propeller geometry is known, it is possible to calculate the section thrust and torque, as below: dT 1 V R2 c dr d C l cos C d sin i 2 dQ 1 V R2 c r dr C l sin C d cos 2 Where, VR = Resultant Speed c = Chord Cl = Lift Coefficient Q = Torque q The total thrust and torque can be calculated by integrating the elemental q antities along the length of the propeller blade. quantities blade 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 22 Propeller Pitch PEMP RMD510 The flattened outside surface of the cylinder above, showing the pitch triangle and the pitch angle . Also shown is the triangle, corresponding to a different radius station r, r which has the same pitch, pitch and thus a larger pitch angle . 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 23 PEMP RMD510 Pitch, Diameter and Number of Blades The propellers are of fixed pitch or variable pitch Pitch,, p = 2 R tan The power needed to turn a propeller depends directly on the number of blades and on the diameter by a power of 5. Doubling D bli the th diameter di t increases i the th necessary power to t 25 = 32. 32 Changing the number of blades from b1 to b2 increases the power consumption to P2 = P1(b2 /b1) if we keep the same diameter. On the other hand, a change in diameter from D1 to D2, changes the power needed to turn the propeller at the same number of rotations per minute to P2 = P1((D2/D1)5 when the number of blades are the same. Putting both trends together (for propellers of the same power consumption) and solving for the new propeller diameter D2 leads to D2 = D1(b1 /b2)1/5 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 24 Propeller Diameter and Tip Speed PEMP RMD510 The above Th b graph h can be b used d tto find fi d the th tip ti speedd andd Mach M h number b for f given i propeller diameter and flight speed. 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 25 Blade Thickness 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru PEMP RMD510 26 Propeller Characteristics (1) 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru PEMP RMD510 27 Propeller Characteristics (2) PEMP RMD510 Typical propeller efficiency curves as a function of advance ratio (J = V/nD) and blade angle (McCormick (McCormick, 1979) 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 28 Propeller Characteristics (3) PEMP RMD510 Typical propeller thrust curves as a function of advance ratio (J = V/nD) and blade angle (McCormick, 1979) 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 29 Propeller Characteristics (4) PEMP RMD510 Typical ratio T i l propeller ll power curves as a function f ti off advance d ti (J = V/nD) / D) andd blade angle (McCormick, 1979) 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 30 Propeller Characteristics from CFD 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru PEMP RMD510 31 Ducted vs Unducted Propeller 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru PEMP RMD510 32 Important Definitions p J = Advance ratio m CT PA TS V p J PS PS CP N = Rotational speed D = Propeller diameter PA = Available power PS = Shaft power V J ND Q = Torque T = Thrust T CT N 2 D 4 P CP N 3 D 5 Pitch 2 r tan (Pitch is specified at 75% of the propeller outer radius, R) 08 PEMP RMD510 TA = Available thrust V = Flow velocity CT = Thrust coefficient CP = Power coefficient = Blade orientation w.r.t. zero lift line = Overall efficiency p = Propeller efficiency m = Drive motor efficiency @ M.S. Ramaiah School of Advanced Studies, Bengaluru 33 Design Concepts PEMP RMD510 • The ducted fan and propeller design is influenced by – Number of blades, B: Small effect on efficiency, ; propeller with more blades p performs better. – Axial flow velocity, V (flight speed): Large pitch propellers may have a good efficiency at design point, but may run into trouble at low axial velocity blades tend to stall. – Diameter: Large diameter tends to give higher efficiency because of increased mass flow rate. – Usually the best overall propellers have a pitch to diameter ratio of 1. – Lift Lif andd Drag D Distribution: Di ib i I Instead d off CL and d CD , it i is i convenient i to specify radial distribution of polar and design angle of attack. The distribution of CL and CD can then be examined. For good performance, L/D should be high. Also it is better to use lower angle of attack for design. – Tip section of air propeller operating at M > 0.7 should be designed to operate at small CL (< 0.5). 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 34 Design Concepts (… contd.) PEMP RMD510 – Density: No influence on propeller efficiency, but affects size and shape. – Force and Power are proportional to density; hence a hydro propeller has smaller dimension than an air propeller. propeller – CT and CP are not affected by density, but T and P are. – A propeller-engine combination will find different operating points d depending di on the th density. d it – For air propeller, the performance of propeller and engine depends upon the altitude also. 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 35 Propeller Design Considerations PEMP RMD510 The stress effects on the engine (the gyroscopic moments) increase exponentially with diameter • Ground clearance requirements. • Propeller strength. • Propeller tip speed. Compressibility constraints dictate that the speed at the blade tips should not exceed about Mach 0.85 0 85 – 560 knots or 290 meters/second at sea level but compressibility effects start at 250 m/s and if the propeller is close the noise may be extremely uncomfortable at that speed. So, for comfort, the tip speed is usually in the range 200 – 240 m/s. m/s Optimum efficiency according to momentum theory versus flight speed for different power loadings P/D² in [W/m²]. 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 36 Design Process • • • • • • • • 08 PEMP RMD510 Design Specifications: Aircraft Speed, Propeller Thrust, Altitude Select suitable values for: Number of Blades, Rotational Speed, Diameter Calculate: Advance Ratio, Ratio Pitch Pitch, Thrust and Power Coefficients Coefficients, Efficiency, Efficiency at 75% R, Tip Velocity. Estimate the radial variation of blade setting angle () and angle of ( ) attack (). Iterate among the above steps to obtain satisfactory performance parameters. Select appropriate blade profiles. Radially stack the profiles with proper orientation to form the complete 3-D blade. Evaluate performance of the propeller experimentally or through CFD simulations. @ M.S. Ramaiah School of Advanced Studies, Bengaluru 37 Standard Blade Profiles • • • • • PEMP RMD510 NACA Profiles E l Profiles Eppler P fil Selig Profiles Clark Y Profiles RAF 6E Profiles Note: The x-y coordinates along with the respective performance d t for data f all ll these th profiles fil are well ll documented. d t d 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 38 Propeller Design Programs PEMP RMD510 • JAVA Prop • XFLR5 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 39 PEMP RMD510 Forces and Stresses Acting on Propeller Blades The forces acting on a propeller in flight are : 1. Thrust is the air force on the propeller which is parallel to the direction of advance and induces bending stress in the propeller. 2. Centrifugal force is caused by rotation of the ppropeller p and tends to throw the blade out from the centre. 3. Torsion or Twisting forces in the blade itself,, caused byy the resultant of air forces, which tend to twist the blades towards a lower blade angle. 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 40 PEMP RMD510 Propeller Design Example Start Design Case 1 Design Specifications D=0.12 m, B=2, N=15,000 rpm, T=11 N T Assume V=20 m/s N=Speed (rpm) B=No. of blades D=Prop. Dia (m) T=Thrust T Thrust (N) P=Linear pitch (m) η =Efficiency P=V/n J = 0.7 Blade angles, β P=2*Pi*r*tan(β) Assume η= 80% Calculate performance parameters, CT , CQ , CP , η CFD analysis Is performance okay? Specifications Diameter=0.12 m Speed=15,000 rpm Thrust=1 N No. of blades=2 Design accepted End 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 41 Computational Domain PEMP RMD510 Propeller mesh Fluid domain INLET The fluid domain was initially meshed with tetrahedral elements and these were then th converted t d to t polyhedra l h d using i FLUENT. FLUENT 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 42 Airfoil Stacking Details Rectangular Cross-section, β=10.812 PEMP RMD510 β=11.769, Chord Length = 10.5 mm, Chord Thk = 0.95 mm β=12.908, Chord Length = 10.5 mm, Chord Thk =0. 99375mm β=14.287, Chord Length = 10.5 mm, Chord Thk = 1.0375 mm Ai f il S Airfoil Sections: ti Selig 1210 β=15.986, Chord Length = 10.5 mm, Chord Thk = 1.08125 mm β=18.129, Chord Length = 10.5 mm, Chord Thk = 1.125 mm β=20.905, β 20.905, Chord Length = 10.5 mm, Chord Thk = 1.16875 mm β=24.625, Chord Length = 10.5 mm, Chord Thk = 1.2125 mm β=29.811, Chord Length = 10.5 mm, Chord Thk = 1.25625 mm β=37.378, Chord Length = 10.5 mm, Chord Thk = 1.3 mm β=43.890, Chord Length = 10 mm, Chord Thk = 1.5 mm 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 43 PEMP RMD510 Propeller Design (…contd.) Calculated : Thrust (N) 1N Thrust Co-efficient 0.1642 Torque N-m 0.0238 Torque Co-efficient 0.0326 Power Co-efficient 0.2 P Power (W) 25 W Case 1: β = 15.798o Numerical results: Speed (rpm) Thrust (N) Torque (N-m) 0.7 15,000 0.7385 0.02080 0.0539 0.0127 32.6730 0.0795 0.4521 0.9 11,111.1 0.2360 0.00722 0.0314 0.0080 8.4051 0.0503 0.5616 J Thrust Co Coefficient Torque Co Coefficient Power (W) Power CoCo efficient Efficiency The propeller was designed for an advance ratio, J=0.7, Speed, N=15,000 rpm, Thrust, T = 1N 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 44 PEMP RMD510 Propeller Design (…contd.) 0.09 0.08 0.07 0.06 0 05 0.05 0.04 0.03 0.02 0.01 0 Torque co-efficient for case 1 Torque Co-efficiient, CQ Thrust Co-effic cient, CT Thrust Co-efficient for case 1 Thrust Co-efficient for case 1 Design Point- CT 0 0.2 0.4 0.6 0.8 1 1.2 Advance Ratio, J 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0 Torque Co-efficient 0 0.2 0.4 1 1.2 1.4 1.2 1.4 0.6 0.12 0.5 0.1 E ffic ie n c y, n P o w e r C o -e f ficc ie n t , C P 0.8 Efficiency for Case 1 Pow er Co-efficient for Case 1 0.08 0.06 0.04 Power Co-efficient, CP 0.02 Design Point- CP 0.2 0.4 0.6 0.4 0.3 0.2 Efficiency for case 1 0.1 0 0 0.8 Advance Ratio, J 08 0.6 Advance Ratio, J 1 1.2 1.4 0 0 0.2 0.4 0.6 0.8 1 Advance Ratio, J @ M.S. Ramaiah School of Advanced Studies, Bengaluru 45 PEMP RMD510 Propeller Design (…contd.) Start Design Case 2 Design Specifications D=0.12 m, B=2, N=10,000 rpm, T=11 N T β at 75% R Blade angles, β P=2*Pi*r*tan(β) J=1 Assume, β=25o Assume η= 80% η Calculate performance parameters, CT , CQ , CP , η CFD analysis Is performance okay? N=Speed (rpm) B=No. of blades D=Prop. Dia (m) T=Thrust T Thrust (N) P=Linear pitch (m) η =Efficiency Specifications Diameter=0.12 m S d 10 000 rpm Speed=10,000 Thrust=1 N No. of blades=2 Design accepted End 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 46 PEMP RMD510 Propeller Design (…contd.) Calculated : Thrust (N) 1N Thrust Co-efficient 0.1642 Torque N-m 0.0238 Torque Co-efficient 0.0326 Power Co-efficient 0.2 P Power (W) 25 W Case 2: β = 25o Numerical results: J Speed (rpm) Thrust (N) Torque (N-m) Thrust Co Coefficient Torque Co Coefficient Power (W) Power CoCo efficient 0.9 11,111.1 0.7461 0.0225 0.0993 0.0250 26.2112 0.1569 0.5693 1 10,000 0.4603 0.0164 0.0756 0.0225 17.1809 0.1411 0.5359 Efficiency The propeller was designed for an advance ratio, J=1, Speed, N=10,000 rpm, Thrust, T = 1N 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 47 Results of Computations PEMP RMD510 Static pressure distribution on the propeller blade (Pa) SS PS Case 2: Beta = 25 deg, Speed = 10,000 rpm 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 48 Results of Computations PEMP RMD510 Velocity distribution on the propeller blade (m/s) SS Case 2: Beta = 25 deg, Speed = 10,000 rpm 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 49 PEMP RMD510 Results of Computations Pressure variation across upstream and o downstream of the propeller (25 blade angle) Case 2: P ressure, (Pa a) 350 Upstream 300 250 200 150 100 50 0 β = 25 deg Downstream N = 10,000 rpm Static Pressure,Ps Total Pressure, Pt D Dynamic i Pressure.Pd P Pd V = 20 m/s -0.3 -0.3 -0.2 -0.2 -0.1 -0.1 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 Axial distance, (m) Propeller Velocity,(m m/s) Velocity variation across upstream and o downstream of the propeller (25 deg) Upstream Velocity -0.3 08 -0.2 23 22 21 20 19 18 17 16 15 -0.1 0 Propeller Downstream 0.1 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 0.2 0.3 0.4 Axial distance, (m) 0.5 50 PEMP RMD510 Results of Computations 0.035 Thrust Co-efficients for Case 2 at 20 and 18 m/s velocities 0.16 0.03 0.14 Thrust Co-effic cient, CT Torque Co-efficient for Case 2 at 20 and 18 m/s Velocities Torque Co-efficien nt, CQ 0.12 0.1 0.08 0.06 Thrust Co-efficient-Case2-20V 0.04 Thrust Co-efficient-Case2-18V 0.02 0.025 0.02 0.015 0.01 Torque Co-efficient-Case2-20V 0 0 0.2 0.4 0.6 0.8 1 1.2 0 005 0.005 1.4 Advance Ratio, J T Torque Co-efficient-Case2-18V C ffi i C 2 18V 0 0 0.2 0.4 0.6 0.8 Advance Ratio, J 1 1.2 1.4 Efficiency for case 2 at 20 and 18 m/s velocities Power Co-efficient for Case 2 at 20 and 18 m/s Velocities 02 0.2 0.6 0.18 0.5 0.14 0.12 Efficienc cy, n Power Co-effficient, CP 0.16 01 0.1 0.08 0.06 Power Co-efficient-Case 2-20V 0.04 0.2 0.4 0.6 0.8 Advance Ratio,J 08 0.2 Efficiency-Case 2-20V 0.1 0 0 0.3 Efficiency-Case 2-18V Power Co-efficient-Case 2-18V 0.02 0.4 1 1.2 1.4 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Advance Ratio, J @ M.S. Ramaiah School of Advanced Studies, Bengaluru 51 PEMP RMD510 Parametric Studies Parametric studies were carried out by changing the blade setting angle β = 28o, 30o, 32o, 34o, 35o, 38o and 40o β = 28º 08 β = 30º β = 32º β = 35º @ M.S. Ramaiah School of Advanced Studies, Bengaluru β = 40º 52 Results of Computations PEMP RMD510 Static Pressure variation across the propeller Case 2: 28 27 β = 40 deg S tatiic pressure, (P a) 26 25 Speed = 10,000 rpm 24 Static Pressure 23 22 21 20 19 18 -0.2 -0.175 -0.15 -0.125 -0.1 -0.075 -0.05 -0.025 0 0.025 Variation of Total and dynamic pressure acros the propeller 0.05 295 Axial position, (m) 290 P ressurre, (P a) 285 Dynamic Pressure Total Pressure 280 275 270 265 260 255 -0.2 08 -0.15 -0.1 -0.05 0 Axial distance, (m) @ M.S. Ramaiah School of Advanced Studies, Bengaluru 0.05 0.1 53 PEMP RMD510 Results of Computations C Comparison i off T Torque Co-efficients C ffi i t for f different diff t blade setting angles 0.07 Torque Co-efficien nt, CQ 0.06 0.05 C Case1-15-79 1 15 79 d degree 0.04 Case2-25 degree 0.03 Case2-30 degree 0.02 Case2-35 degree 0.01 0 0 Case2-40 degree 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 Advance Ratio, J Comparison of Thrust Co-efficients for different blade setting angles Thrust Co-effic cient, CT 0.25 0.2 0.15 Case1-15.79 degree Case2-25 degree 0.1 Case2-30 degree Case2-35 degree 0.05 Case2-40 degree 0 0 08 0.2 0.4 0.6 0.8 1 1.2 Advance Ratio, J @ M.S. Ramaiah School of Advanced Studies, Bengaluru 1.4 1.6 1.8 54 PEMP RMD510 Results of Computations Comparison of power Co-efficients for different blade setting angles Pow wer Co-efficie ent, CP 04 0.4 0.35 0.3 0 25 0.25 0.2 0.15 0.1 0.05 0 0 08 02 0.2 04 0.4 06 0.6 0.8 0 8 1 12 1.2 Advance Ratio, J 14 1.4 16 1.6 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 18 1.8 55 PEMP RMD510 Results of Computations Comparison of Efficiencies for different blade setting angles 0.7 Efficiency y, 0.6 Case1-15.79 deg Case2-25 deg C Case2-28 2 28 d deg Case2-30 deg Case2-32 deg Case2-34 deg g Case2-35 deg Case2-38 deg Case2-40 deg 0.5 0 0.4 0.3 02 0.2 0.1 0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Advance Ratio, J 1.4 1.6 1.8 Variation of Propeller Efficiency with Advance Ratio 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 56 Results of Computations PEMP RMD510 Efficiency versus different blade setting angles Prop eller Eff iciency, 0.8 0.75 0.7 0.65 0.6 0.55 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 Blade setting angle, Beta (deg) Variation of Propeller Efficiency with Blade Setting Angle 08 @ M.S. Ramaiah School of Advanced Studies, Bengaluru 57 Session Summary PEMP RMD510 The following aspects of ducted fans and propellers have been di discussed d in i this thi session: i 08 Working principle of propeller and ducted fan Slip stream, momentum and blade element theories Propeller performance parameters Propeller design procedure with design example @ M.S. Ramaiah School of Advanced Studies, Bengaluru 58