Consider an airfoil in a high-­?speed wind tunnel. At the minimum-­?pressure point on the wing, the velocity is 900 ft/s. If the test section flow velocity is 750 ft/s at standard sea-­? level conditions:

a) Calculate the pressure coefficient at this point on the wing.

b) Calculate the critical pressure coefficient corresponding to this flight condition.

c) Comparing your answers from parts (a) and (b), what conclusion can you make as to the nature of the flow over the wing? What is the significance of this conclusion with respect to the drag on the airfoil?

a) Briefly discuss how plastic deformation occurs in crystalline materials. Discuss the important methods of strengthening used in (i) cold rolled 1018 steel, (ii) 2024Al alloy in T6 heat treated condition, (iii) brasses, and (iv) quenched and tempered 1045 steel.

refrigerant 134a enters the evaporator of a refrigeration system operating at steady state at -12°C and a quality of 20% at a velocity of 7 m/s. At the exit, the refrigerant is a saturated vapor at -12°C. The evaporator flow channel has constant diameter of 1.7cm.

Determine the mass flow rate of the refrigerant in kg/s

Determine the velocity at the exit in m/s

Air enters a turbine operating at steady state at 6 bar, 1600 K and expands to 0.8 bar. The turbine is well insulated, and kinetic and potential energy effects can be neglected. Assuming ideal gas behavior for the air, what is the maximum theoretical work that could be developed by the turbine in kJ per kg of air flow?

thermo II question

A jet engine does not produce shaftwork; how is power produced?

Gd and T
Circle T if the statement is true. Circle F if the statement is false.
1.      The MMB and LMB symbols are only used if the datum feature has size RMB is implied if the datum feature has size and no boundary symbol is used. No material boundary symbol can be used if a feature does not have size.
2.      Unit straightness can be used if the part must be controlled per unit of measure as well as over the total length.
3.      Specific area flatness should be avoided on very large parts
4.      Circularity is a profile tolerance.
5.      Cylindricity is identified by a radius tolerance zone that establishes two perfect concentric cylinders.
6.      A parallelism tolerance zone must be smaller than the size tolerance of feature.
7.      The perpendicularity of a shaft, such as a stud or pin, to a datum feature establishes a cylindrical tolerance zone.
8.      The note EACH ELEMENT must be applied to a perpendicularity feature control frame.
9.      An angularity tolerance must have a basic angular relationship to a datum.
10. The tolerance zone descriptor of a concentricity tolerance is R.
11. Concentricity is used to establish the relationship between the axis of or more cylindrical features of an object.
12. Surface straightness can violate perfect form at MMC.
13. Geometric tolerances imply RFS unless otherwise specified.
14. A concentricity tolerance should be used if there is a need to control the axis, as in a dynamically balanced shaft. Otherwise, it is recommended that a runout or positional tolerance be used.
15. 69. A coaxial relationship can be controlled by a positional tolerance at M with the datum reference at MMB, LMB, or RMB.
16. LMC is often used to control minimum edge distance or wall thickness.
17. True position is the theoretically exact location of a feature.
18. The datum reference frame exists in theory. The theoretical reference frame is simulated by positioning the part on datum features to adequately relate the part to the datum reference frame and to restrict motion of the part relative to the reference frame.
19. When reference is made to the datum reference frame, the primary datum should be given first, followed by the secondary and tertiary datums. This is referred to as datum precedence.

Refrigerant 134a enters an insulated compressor operating at steady state as saturated vapor at -26^oC with a volumetric flow rate of 0.18 m³/s. Refrigerant exits at 8 bar, 70^oC. Changes in kinetic and potential energy from inlet to exit can be ignored.

Determine the volumetric flow rate at the exit, in m³/s, and the compressor power, in kW.

Consider a vertical plate of dimension 0.25 m × 0.3 m that is at Ts= 90°C in a quiescent environment at ?T?= 20°C. In the interest of minimizing heat transfer from the plate, which orientation, (A) or (B), is preferred? What is the convection heat transfer from the front surface of the plate when it is in the preferred orientation? Evaluate the properties of air at the film temperature.

Determine the convection heat transfer from the front surface of the plate when it is in the preferred orientation, in W.

Airflow through a long, 0.15-m-square air conditioning duct maintains the outer duct surface temperature at 10°C. If the horizontal duct is uninsulated and exposed to air at 35°C in the crawlspace beneath a home, what is the heat gain per unit length of the duct? Evaluate the properties of air at 300 K. For the sides of the duct, use the more accurate Churchill and Chu correlations for laminar flow on vertical plates.

What is the Rayleigh number for free convection on the outer sides of the duct? 7709251

What is the free convection heat transfer coefficient on the outer sides of the duct, in W/m²·K? 4.87

What is the Rayleigh number for free convection on the top of the duct? 965073

What is the free convection heat transfer coefficient on the top of the duct, in W/m²·K? NEED HELP HERE

What is the free convection heat transfer coefficient on the bottom of the duct, in W/m²·K? NEED HELP HERE

What is the total heat gain to the duct per unit length, in W/m? NEED HELP HERE

I cant figure out 4,5 and 6. I swear they are correct but the online homework won't take it.

Part 1. Select an object from your everyday life that GD&T could be applied to. Attach a graphic image of it (a photograph, a scanned sketch or a computer generated drawing) in JPEG format here.

Part 2. Identify two primary functions of this part (e.g. must assemble to other part(s), smooth rolling, must not wobble when placed on a flat surface). Briefly describe the functions (maximum of 200 words).

Part 3. Assign a minimum of two geometric tolerances (including at least one that requires the use of datums) to the part to ensure that the part will successfully achieve its two primary functions. Assign datums as necessary. Create a sketch or drawing to show where the datums and tolerances will be applied. Assign values for the tolerances, however you will not be marked on the magnitude of the tolerances.

Part 4. Briefly describe (maximum of 150 words) how the part would be inspected to verify that it meets the geometric tolerances.

Write a program usingif-elseif-else statements to calculate the real roots of a quadratic equation ax^2+bx+c=0

The data file contains displacement (in mm)-load (in N) data for a mechanical test that was conducted on an unknown metal. The initial length and diameter of the specimen are also given.

a. (5 pts.) Using the data and a computer program (such as Excel), create an engineering stress-engineering strain graph with proper labels. The stress axis should be in the units of MPa. You do not need to show your spreadsheet or software code used to make the graph. Just provide the resultant graph.

b. (3 pts. each) Using the resultant stress-strain graph determine the following: 1. Young’s modulus 2. 0.2% offset yield strength 3. Ultimate tensile strength 4. Strain at fracture 5. Plastic strain after fracture

DATA:

1) Identify the type of steel (alloy?) with values similar to the following:

Modulus of Elasticity = 189.75 MPa

Ultimate Tensile Strenght (UTS) = 740.05 MPa

Cup Cone Fracture

Toughness = 4.84 MPa

2) Identify the type of treated steel(alloy?) with values similar to the following:

Modulus of Elasticity = 326.07 MPa

Ultimate Tensile Strenght (UTS) = 408.97 MPa

Cup Cone Fracture

Toughness = 140.91 MPa

My guess is that this one is some type of heat treated steel, the steel being the same type as 1) but I do not know how to identify it.

3) Identify the type of brass (alloy?) with values similar to the following:

Modulus of Elasticity = 84.88 MPa

Ultimate Tensile Strenght (UTS) = 480.34 MPa

Diaginal, Rough Fracture

Toughness = 76.47 MPa

All of these values have been calculated from a Tensile Test machine and by hand so there is room for error.