Fluid Dynamics & Flow Analysis Flashcards
7 cards from real SPED practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Fluid Dynamics & Flow Analysis flashcards as text
The void fraction in two-phase flow is defined as the ratio of:
Answer: Gas cross-sectional area to total pipe cross-sectional area
Void fraction α = Ag/A, the fraction of pipe cross-sectional area occupied by the gas phase at any given cross-section.
In the Baker flow pattern map for horizontal two-phase pipe flow, which regime is characterized by the gas phase flowing continuously at the top of the pipe with liquid along the bottom?
Answer: Stratified flow
Stratified flow has the liquid phase settled at the pipe bottom by gravity and gas flowing continuously above it, typical of low-velocity horizontal systems.
When applying the Bernoulli equation between two points in a real piping system, which additional term must be included?
Answer: Head loss due to friction and minor losses
The extended Bernoulli equation includes a head loss term hL (friction + minor losses) to account for energy dissipation: P₁/γ + V₁²/2g + Z₁ = P₂/γ + V₂²/2g + Z₂ + hL.
The slip ratio in two-phase flow is defined as:
Answer: Ratio of actual gas velocity to actual liquid velocity
Slip ratio S = Vg/VL, the ratio of actual (in-situ) gas velocity to actual liquid velocity; S > 1 indicates gas travels faster than liquid.
For flow through an orifice plate meter, the discharge coefficient Cd is typically less than 1.0 because:
Answer: Vena contracta formation and friction reduce the effective flow area below the geometric orifice area
The vena contracta (flow contraction downstream of the orifice) and viscous losses make actual flow less than the theoretical ideal, giving Cd typically 0.6–0.65 for standard orifices.
In piping system design, a check valve's cracking pressure refers to:
Answer: Minimum upstream pressure required to open the valve against backflow
Cracking pressure is the minimum differential pressure needed to lift the valve disc off its seat and initiate forward flow.
The Joukowsky equation for maximum pressure rise due to water hammer is expressed as:
Answer: ΔP = ρ·a·ΔV
The Joukowsky equation ΔP = ρ·a·ΔV gives the instantaneous pressure rise, where ρ is fluid density, a is wave speed, and ΔV is the change in flow velocity.