Identify the turbine type that is not an impulse turbine from the list below (consider the primary energy conversion principle at the runner).

Introduction:Hydraulic turbines are broadly classified as impulse or reaction types. Impulse turbines extract energy solely through jet momentum at essentially atmospheric pressure in the runner, whereas reaction turbines experience a pressure drop across the runner passages.

Given Data / Assumptions:

• Compare by operating principle, not geometry alone.
• Impulse examples: Pelton, Turgo, cross-flow (Banki, as commonly categorized in practice).
• Reaction examples: Kaplan (axial), Francis (mixed).

Concept / Approach:Kaplan turbines are axial-flow reaction machines with adjustable runner blades and a draft tube, operating with substantial pressure change across the runner. In contrast, Pelton, Turgo, and Girard are classical impulse designs using free jets. Cross-flow turbines are generally treated as impulse machines because the runner operates with jets at near-atmospheric pressure, even though the flow path is through the runner interior.

Step-by-Step Solution:1) Classify each listed turbine by principle.2) Identify which experiences pressure drop in the runner (reaction).3) Kaplan is reaction; others listed are impulse.

Verification / Alternative check:Presence of draft tube and submerged outlet is a hallmark of reaction turbines like Kaplan.

Why Other Options Are Wrong:Girad/Turgo/Pelton: classic impulse types.

Banki (cross-flow): commonly treated as impulse; runner sees atmospheric pressure jets.

Common Pitfalls:Confusing flow direction (axial vs radial) with impulse/reaction classification; they are related but not the same criterion.

Final Answer:Kaplan turbine