창의-열유체-3

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1 (1) Thermal, Fluid System and Heat Transfer

2 Airplane

3 Airplane Design?

4 Gas Turbine Engine GE 90 Engine

5 Gas Turbine Engine

6 Schematic View of Gas Turbine Engine

7 T-s and P-v diagrams

8 Gas Turbine Brayton cycle 1-2: COMPRESSOR 2-3: COMBUSTER 3-4: TURBINE 4-1: HEAT REJECT Ideal Thermal Efficiency T 1 η = 1 T 3

9 Gas Turbine Brayton cycle T 3 Turbine inlet temperature T 2 T 1 s Maximum work T 2 = T1 T3

10 Variation of TIT over recent years : NEW COOLING CONCEPT 1600 FILM IMPINGEMENT CONVECTTION SIMPLE COOLING UNCOOLED TURBINES ALLOWABLE METAL TEMPERATURE

11 Turbine Blade Turbine Vane

12 Turbine Vane/Blade Film Cooled Blade/Vane Several rows of cooling holes Coolant Ejection Protect the Surface

13 Photos of Cross-section of Turbine Blades with Internal Cooling Passages

14 Rotor Blade Cooling Impingement Cooling Film Cooling Convective Cooling 7FA 501G Pin Fin / Slot Cooling

15 Turbine Blade Modeling Tube Flow Inside Tube (Cooling air) Tube wall Outside tube (Combustion gas)

16 Inside and Outside Tube Flows Forced flow in a tube Forced flow over a cylinder

17 Thermal Design? Q = h o A (T gas T wo ) Q = k A (T wo T wi ) / L Q = h i A (T wi T cool ) h i T wi

18 To Design Thermal Components? 1. Estimate h 2. Obtain a correlation equation Nu = hl / k = c Re m Pr n 3. Enhance h = Re 0.5 Pr 0.333

19 Applications of ducts with ribs and pin-fin arrays Gas turbine internal cooling passages with ribs and pin-fin arrays

20 Modeling Internal Cooling Passage Internal cooling passages of turbine blades Break laminar sublayer, promote turbulence, improve flow mixing, induce various vortices Flow Augment heat transfer greatly (Additional friction loss penalty)

21 Design Parameters (1) - Rib Turbulators p α e Rib height and width Rib-to-rib pitch Rib angle of attack Rib arrangement Rib shape

22 Basic flow patterns and heat transfer (1) 4 - around the transverse ribs with rib angle = 90º Nu Nu Recirculation Reattachment Re-developing boundary layer Separation e Rib Rib vortex x/e vortex

23 Basic flow patterns and heat transfer (2) Secondary flows induced by angled ribs Secondary flow pattern Rib Parallel rib array Cross rib array Flow reattachments Rib Flow separation Path lines Kilm et al. (1999) Mainstream Mainstream Downward flow Flow Rotating secondary flow Upward flow

24 Flow patterns and heat transfer? Mainstream Rib turbulator Low heat transfer region Flow z/e z/e Steep gradient x/e x/e Potential hot spots, large thermal stress

25 Contour Plots of Nu/Nuo Flow 10.0 A90N A90N2 5.0 z/e 0.0 z/e Flow z/e A90N x/e z/e A90N x/e x/e x/e 1.0

26 Thermal Design? Q = h i A (T wi T cool ) Q = 15 kw h i = 2000 w/ C m 2 A = pdl = 0.01 m 2 T cool = 700 K T i = 15,000/(2000)(0.01)+700 =1450 K h i = 15,000/(0.01)( ) = 3000

27 Types of Gas Turbines

28 Fuel Cell

29 Small Gas Turbine - kw - - / Hybrid - -

30 Gas turbine Fuel cell Hybrid System : 800~1000 C (SOFC)

31 Hybrid System Gas turbine with Cycle improvement Gas turbine-fuel cell Hybrid system Gas turbine Combined cycle Advanced Turbine System Diesel and gas engine

32 Hybrid System

33 Micro Gas Turbine 1) (Battery ) : g : 10 g/hr ( ) 2) 1) 2)

1600 K Pressure ratio 4:1 Fuel consumption 7 gram/hr

34 Micro Gas Turbine Micro Gas Turbine (MIT) Dimension 12 mm OD 3 mm Combustor Temp K Pressure ratio 4:1 Fuel consumption 7 gram/hr Rotor speed rpm Weight 1 gram Air flow 0.15 gram/sec Power output 16 W

35 Four Forces on an Aircraft What forces are generated by fluid?

36 Drag and Lift Drag is the aerodynamic force in the direction of upstream velocity. Lift is the aerodynamic force normal to upstream velocity Drag and Lift are generated by the interaction and contact of a solid body with a fluid (liquid or gas).

37 Lift or Magnus Effects 1. Disaster of a Racing Car (PORSCHE) due to Lift

38 Lift or Magnus Effects 2. R. Carlos Free Kick Brazil vs France (1997)

Closed system (control mass): no mass crosses the boundary. CVs have solid characteristics. - Forces may act upon CV boundaries.

39 Control Volume Analysis CVs (Control volumes) are artificial boundaries used to simplify analysis (similar to free body diagram in solid mechanics). CVs (open system) have porous surface (control surface), so mass can cross the boundary. Cf. Closed system (control mass): no mass crosses the boundary. CVs have solid characteristics. - Forces may act upon CV boundaries. - Forces may be exerted by CV boundaries. Examples Closed System Control Volume (a) simplified physical view (b) Isolated using a control volume

40 Examples of positive displacement machines Tire pump Human heart Gear pump Most positive displacement machines are used in hydraulic system.

41 Classification of Turbomachines Working fluid Liquids: pumps, hydro turbines Gases: compressors, fans, blowers, wind turbines, gas turbines Flow path Axial flow, mixed flow, radial flow turbomachines

42 Turbomachines and Supersonic Flow

43 Vortex

44 Flows around a Cylinder A: Re<<1 B: 4<Re<40 C: 40<Re<3*10 5 D: 3*10 5 <Re<5*10 5 E: 5*10 5 <Re

45 Inside and Outside Tube Flows Forced flow in a tube Forced flow over a cylinder Flow through a tube bank

46 Condenser

47 Heat Transfer Tube flow Inside Tube (refrigerant) Tube wall Outside tube (air, room) Condenser Evaporator

48 Pipes which have fins

49 Different boiling regimes Transition boiling Nucleate boiling Natural convection boiling Film boiling

50 Flow boiling in a tube

51 Two phase flow in a pipe (1) Two phase flow in a vertical circular pipe

52 Biomimetics - Glider(1889)

53 Biomimetics Wright Brother s Airplanes

54 Biomimetics - Aircraft wing

55 Aircraft wing

56 Aircraft wings leading & trailing edges

57 Airfoil Shape (NACA) - Trout

58 Upward deflected wing

59 Humming bird

60 MAVs using Flapping Wing

61 Reduction of Drag : Shark s Skin

ePapyrus PDF Document

ePapyrus PDF Document 19 3 (2009 9 ) J Korean Soc Occup Environ Hyg 2009;19(3):240~249 Numerical Study on Ventilation Method for Temperature Control of HRSG Building Chul Hwan Kim Jong Wook Lee Hoon Ki Choi Geun Jong Yoo Dept.